I have not come across any videos of you fixing a 2000/2007 ford focus. Which I'm shocked about. You're a smart. Smart ass. mechanic Who dumbs it down without making yourself sound dumb. My car is having problems. I can't find the causing issue. I'm just shocked you haven't had more of these focus come
That's why I stay tuned to your channel, because you're "REAL LIFE" no fake news, you bring real life experience to the front and center! Being a good technician/mechanic, is really hard work, and you have to be smart, and I've learned that experience brings wisdom. Thank you Mr. O.
Eric , you are certainly a detective in diagnosing ANY vehicle trouble - it really is amazing the level of understanding you possess. Reading some of your bio - of how you grew up in your dad's shop ? Each and EVERY UA-cam video you make displays your IMMENSE Skills - for getting to the heart of the problem and locating the cause of failure. You indeed dig in - and run every possible test - to confirm your diagnosis - and , of course , this is the EXACT skill that places you in the preferred category of auto repair shops - YOU find and repair the problems many other shops cannot . I place you in the SUPER TECH category of technicians. You ARE that good - and I understand your , Mrs O , when she made the comment in your UA-cam video in which you repaired a shorted connector in her car ( one of your children spilled coke ) and it got into the connector, to the point - Mrs O said , you fix any vehicle you attempt to fix. AGAIN , THANK YOU MUCH for sharing your VAST knowledge of auto diagnosis and repair - I learn something from EVERY video you make and take a nugget of what you teach and place it in my own thought for diagnosing and repairing my personal vehicles. 👍👍👍✌️✌️✌️😊
A/c voltage? Check the diode pack. All kinds of nutty things happen with dirty voltage. My eye opener was a brake warning light that stayed on all the time. It was a Ford ranger.
Eric from watching your videos I can tell you're a big fan of the classic reach around lol. You are one hell of a mechanic...its a shame more mechanics don't take pride in their work the way you do. God bless you and your family!
I love these difficult diagnoses. It really shows how important troubleshooting skills are and that car repair isn't just connect up a Verus and fire the parts cannon!
Now would be a great time to pull out that potentiometer from your AESWave backprobe kit, and use it to substitute for the pressure sensor. You can adjust it to get whatever value you want to see, and determine if the voltage still goes away at higher RPMs. This is a strange one, for sure, but the ECM does actually seem to be reporting what it is seeing.
Yeah I was thinking way early in the video "stick a couple of resistors between 5v and signal, then signal and ground, then see if the behavior persists. If it does not, bad sensor (even though it seems really weird that such a thing is that predicatable).
You know what a failure is ? It's someone that won't try. I don't see that in you I see a fellow that gives everything he does 200% plus.... All your videos are always awesome praying for you always 😃👍👍👍👍👍👍
I LOVE your channel Eric. And these are the reasons why diag is one hour isn’t always correct and ANOTHER reason why service whiters have to have been in the field. I love your videos and just point blank your awesome and an inspiration on all levels! Thanks for the video a lot of fun
Hey Eric, why do you think about putting an ECM into it? It seems like the sensor itself does that. You checked the voltages at the fuel tank and they were corresponding with that you saw on the live data. You checked it being unplugged also, and it didn't do that. My suspicions goes to the sensor. I would recommend you open the gas cap and recheck it then. Don't want to say the evap valve opens and put the whole tank under great vacuum, but when the vacuum numbers would change, the sensor might react little different. Maybe it's a "dead spot" in the sensor like someone in the comments suggested, and opening the gas cap might prove that. Anyway, can't wait for part two, thanks Eric! :)
I love these kinds of diagnostic videos. No actron is gonna fix this puppy. Lol. Eric is going down the right path testing all the appropriate avenues to try and narrow the problem. Seems wierd that a ECM goes faulty just on Evap issues for these escapes. Is just one part of the internal circuitry bad?? Im leaning towards testing the fuel tank for leaks with the smoke detector machine. I mean if the trouble code is being set for an evap leak shouldnt we test for that first?? Why does it have to be an electrical problem out of the gate? I have no doubt Eric O will find the problem. Great step by step diagnosis.
Is that fuel pump duty cycle controlled? At a higher rpm and higher duty cycle increased vacuum in tank maybe? I'd be more confident replace that sensor than the ecm. You proved the ecm is providing everything it needs to work and it didn't do it with a substitute signal. That right there makes me want to change the sensor
Hi man, great channel btw. I would disconnect the sensor from the ECU and plug it "standalone" to a 5v power supply and read the signal produced @3000 rpm. Keep up with the good work!
He showed the 5v reference that feeds the FTPS is the same 5v source that feeds the TPS and the DPFE and the anomaly wasn’t showing up in those two sensors, so that confirms that the 5vr signal coming from the ECU is okay. Supplying a standalone 5vr signal to the FTPS would probably not produce any different results. What I think is happening is there is some kind of vibration resonance frequency at 3k rpm that the FTPS doesn’t seem to like and so the voltage drop may be the result of an internal failure of the FTPS that only shows up at that frequency.
3000 rpm maybe getting vacuum into tank and sensor failing under vacuum or is the valve stuck closed allowing to much vacuum in the tank pulling it all the way down. This is a great video as always buddy keep up the great work. I wish I could watch all your live streams you have been doing. Can't wait for the next video
have a feeling this might be the same as out mazda tribute theres a tsb where charcoal canister will be contaminated by fuel and it would plug the vent. and have a faulty purge valve that opens at higher rpm causing a low voltage or creating huge negative pressure in your tank. check fuel trim numbers on your data pids. hope this helps.
Great stuff...I keep thinking, garbage in garbage out meaning the ECU seems to be working with values it's getting. I'm leaning toward sensor. They are so sensitive to begin any variable at 3k may trigger a glitch. Thank Mr O, it's fun to follow along.
i would check the tank itself to see if at 3 k rpm the tank is somehow being put under a vacuum. and also testing the sensor resistance by itself under a 3krpm to see if it increases at 3 k to show an actual sensor voltage drop itself while disconnected from the harness on the sensor side. if it still has a voltage drop on the sensor side at 3k then my guess would be something fishy may be going on with the vacuum system , where somehow excessive vacuum is getting into the tank. but it is a severe instant voltage drop and not gradual.. so idk probably just rambling just a thought i had .
Boy that would have to be a very fast vacuum put on it to evacuate the tank that fast and I do not think it would pull it to zero volts because that is outside the operating range of that sensor ;)
Maybe the pressure really is being reduced at high rpm's if the tank isn't venting??. Small engines have that issue all the time. Can you remove the gas cap and see if it still does it?
The sensor will not pull down to 0 volts, not even if it had extreme vacuum, a functional sensor displays between 0.5V to 4.5V or even less. That is how the ECM can distinct shorts vs stuck low. It is a wicked short somewhere down the wire or perhaps ECM who can tell.
I had a one where after the car ran awhile the the lights would start flashing like when someone sets the alarm. The higher the rpms went they would flash more. It wouldn't do it with the Alternator unhooked. It was a bad window motor/module shorted feeding voltage back to the BCM causing the lights to flash at higher rpms. That made me think of that.
Have you ever had the REAR DOOR LOCK MODULES SHORT OUT??? I took a 2004 Ford Escape to the Ford dealer 3 times. EVERY TIME THE VEHICLE GOT HOT FROM THE AIR TEMP OUTSIDE, THE FLASHERS WOULD ACTIVATE & THE HORN WOULD SOUND LIKE GABRIEL BLASTING HIS TRUMPET. ACCORDING TO MURPHY'S LAW A WATCHED POT NEVER BOILS. I let the dealer keep it and an hour after I left the ESCAPE DID IT'S THING AND THE MECHANIC FOUND THE BAD REAR DOOR LOCKING SENSOR. IT WAS REPLACED AND IT NEVER HAPPENED AGAIN. I prefer PAUL'S AXIOM OF MURPHY'S LAW: YOU CANNOT FALL OFF THE FLOOR
pull the sensor out of the tank and check to see if the problem is still there at atmospheric pressure without any variables of in tank pressure that should determine if it’s the sensor either way It looks like it needs a sensor at this point because even with a little in tank vacuum it should drop out
This is a cool diag so far Eric! I think you proved ECM and wiring integrity is OK. Maybe the sensor is not "linear" anymore? At this point I am curious to pull the FTP sensor out of the line and maybe manually put some pressure/vacuum on there... Does Keith already know what the problem is? xD
Ivan you know what popped in my head also? Feedback into the pcm from a coil. That leakage we just learned about in Ziegler's class. You think a coil stress test would show anything?
Coil feedback can definitely do funky stuff! Eric didn't see any voltage spikes on the 5V ref or signal wires at the sensor. However, a Vantage Pro set on a long timebase "graphing meter" setting can easily miss such quick events. I wanted to see a Pico on there :)
At the point when you’ve confirmed the sensor at the tank is acting independently of the 5V reference, my next move would have been to unplug the sensor and measure resistance or shermnangle a separate pressure gauge onto the tank. My inkling would be that it’s not lying.
Good one just needs more testing to isolate it. Some make you think outside the box or go back to basics but I'm sure you figured it out. You already figured out what triggered it and it's repeatable so the rest is a piece of cake :D
Ohhhhhhh just wait and see what the cause is... trust me it will make you want to quit working on cars, oh and FYI, it has nothing to do with the EVAP system or vacuum :)
I figured as much especially if it's from another system not even related...you have to have an open mind diagnosing nowadays. It's the head scratchers you wonder if you may have to ship it out broken but then it always comes to you...sometimes waking up at 3AM from a dead sleep and having to go to the shop right then to see if you're right and then have the police converge on your shop b/c they think you're breaking in...I've regressed that's another story :D
O I have been there wayyyyyy to many times at 3am haha. Your gonna like this one trust me. System not related is true but you won't believe what one lol
Eric O, my problematic 03 Mazda Tribute had the same issue. It threw a P0451 code, and changing the totally unrelated power steering switch cleared it.
From my decades of EEC-IV experience, Ford uses the term "signal return" for the sensor low reference (ground), not for the signal itself, which is what you seem to be doing while thinking out-loud.
Disconnect the purge line from the vapor management valve redo the rpm test as rpm goes up volume flow goes up the normally open vent valve can compensate at idle not high rpm then make sure the canister isn't partially plugged have seen this on the f150 of that year I think their is a tsb on the f150
When I picked up my 01 Escape a month ago for $300, I had a hell of a time setting full readiness. Drove 200 miles and cat and evap hadn't set. Took 3 more days for evap to set because it was so warm outside here and the fuel tank wasn't at the right level... cat finally set though. Readiness is finicky in these cars, have to follow the drive cycle almost to the T
First thing that came to my mind was an internal short inside the sensor that is aggravated by vibration at that particular RPM. I don't really have enough experience with OBD-II to know if that's a common issue, or if it's even possible. I figure since there's a ground, and power (5v ref), it CAN possibly short internally. HMMM!! :)
it could be as simple as a faulty sensor, I would do the same test while the tank cap is open to make sure no pressure change effects the sensor , also measuring the Resistance while revving instead of the voltage while with the sensor disconnected, if it doesn't work I would connect a resistor that's similer to the sensor Resistance between 5v and and signal and do the same test if same problem occur I would check the ecu next,, good luck Eric we are waiting for part 2
I don't know if it will help or not but I did notice that when you had the other sensor pids up they showed a small glitch at the same time as when the Fuel pressure sensor was dropping signal. I think looking at something inline with it somewhere might be worth a look. Could be another sensor that is on the same line that is RPM based could be causing an issue. That is my take on it. Probably wrong though.
Since the pressure sensor is essentially a pressure transducer... and with the testing you have done. If it is not the something wacky in the box, I would be suspect of a dead spot in the sensor at a certain vacuum or pressure. Can you get a vacuum gauge on the tank and see what the actual vacuum is at 3-4K RPM? Can you hook a vacuum pump on the sensor and see if you can reproduce the 0V reading at a certain vacuum or pressure. If it does go 0v at a certain pressure/vacuum, is that a normal range that should be in the tank? If not then the sensor may be working as designed and you may be seeing the effect of something else wrong in the EVAP/Fuel Delivery system.
I suspect the FTP sensor as well. I think there's a worn section in the transducer that effectively opens the return circuit to the ECM. Thinking about it as if it were a throttle position sensor, it's likely that the beginning section of the internal contacts have been scrubbed excessively over 14 years of use, causing the issue. It happens at 3000 rpm because the ECM commands the purge solenoid open, and that vacuums the tank to the exact point where the circuit opens inside the FTP sensor. I've seen EVAP systems that open the purge solenoid above idle because the engine can tolerate the extra fuel vapors at that point without causing a drivability issue; if it happened at idle, the engine would surge and lope because of the extra fuel vapor going into the intake. I had the same idea as you, FrugalPrepper, to "bench test" the FTP sensor with a vacuum pump attached to see if the condition can be duplicated with the engine off. I always tend to suspect the component with moving parts first, because, by probability, it is more likely to fail than an ECM with no moving internal parts.
When you showed the dpfe voltage trace there was a 'wiggle' at the same point in time as the voltage dropped off on the pressure sensor, so there is something in common with the other sensors. My humble suggestion would be to disconnect the sensor from its pipe and repeat the test, this would confirm the above comments, maybe the vac suddenly changes at 3k due to the valve opening, old 90's rovers used to so something like this.
I think that EVAP purge valve between intake manifold and charcoal canister only opens at above 3,000 rpm so that the engine can cope with the addition of unmetered air. If the vent valve fails to open at this time to allow external air to flush out the canister then the tank will be subjected to intake vacuum and the tank pressure transducer will sense this.
Out on a limb (haven't watched part 2 yet)... open the gas cap and try again. My gut tells me the sensor is telling you the truth, and a vacuum is being pulled on the tank... real easy to check!
I would try the sensor itself maybe it was really over filled and the fuel compromised the sensor a flat spot of sort I know it's a long stretch but it is going to be the sensor or the pcm. It is a Ford they can be tricky.
Im along for the ride at 15 minutes. What I would have tried is taking the cap off the fuel tank, blocking the fuel tank filler trapdoor open so the tank is truly open to atmosphere, and repeat the test. I would want to know if the sensor was reporting accurate data.
Purge valve stuck open and vent valve restricted or stuck partially closed. Would be crazy if tps was at fault. Ive been running into some crazy stuff lately so who knows lol
Cool, But in this case I think you got that sensor in the act ;) The the small glitch at idle was the real give, and the un plug test - fuel tank pressure sensor is bad, cool that its right at 3k but my best guess is vibration, where is the tap test? ;) Cheers.
"Vintage Ford" Hah! making me feel old... Great video as always! Keep up the hard work and thank you for sharing your time with us. You are inspiring my friend.
Ford would more than likely recommend replace and recheck (All parts.? Carpet bombing). I would however wonder if the purge is sticking open slightly causing a vacuum only at 3k rpm...? (You were getting RPM surging when fussin' with that valve) Could try a vacuum gauge or transducer in place of the FTP sensor. Maybe the sensor and PCM aren't wrong. If that makes any sense. Keep us posted!!!
You sir, are very correct! Even with the scanner refresh rate on the data that is a very sharp drop to 0 volts... However, I am kinda diggin' the idea of a defective sensor. Ford again would say "replace with known good and recheck". Not a huge fan of that idea. But, attempting a "bench test" on the FTP sensor would rule that out 100%. Dig out the ol' vacuum pump and make the "pressure" a more "controlled " variable. At the same time could hook up a vacuum gauge to the tank to see whats actually going on in there..? Just throwing ideas good and/or bad your way.
13:00 So this is when we COULDNT jump vref to sig rtn (to possibly produce a circuit high code) verifying circuit integrity being that its not like a potentiometer? Because no variable resistor? Just curious. Awesome video as always Sir.
Only other test I can think of is try a new sensor to check if it’s shorting under that specific load/vacuum. And you could also cut reference wire while leaving connector plugged into sensor to see if PCM is shorting it out under 3k rpm load, just shooting the sh*t with some ideas
On ford escapes if the customer tops the tank it will get liquid fuel in the return line , it sometimes takes awhile liquid to dissipate , in the mean time you have a code. Blow out the return line,reset codes should clear.
From the tests you did, ground is good, 5V ref is good and the signal drops at 3K RPM. two things can do this in my opinion. Excessive vacuum in the tank. Not likely... or bad sensor. other option is to simulate a sensor reading with a resistor... But I suspect you need to replace that sensor...
G'day, Mr. O! Well, take a break, and get some... Lunch! Sharing: Just FYI, I have had three or four of these with this issue and have never been able to locate the exact point in the wiring where the problem is. This is after hours of monitoring power and ground and V.ref with the entire harness open and bending/flexing wires one at a time... Pin 90 is reference voltage supplied by the PCM to several of the sensors. Unplugged it should have zero volts. Plugged in with the key on it should have 5 volts. It should never have battery voltage. Cheers! :-)
Has to be a variable like vacuum, line noise or a drop in resistance in the Ecm. I would AMP clamp the return wire and the feed wire. Voltage is not your only thing to look at.
Possible the sensor itself has become faulty and gone super sensitive so at higher rpms the vacuum registers higher than normal? What if you simulate a sensor with a couple resistors as a voltage divider connected to the 5v and ground and tapping into the signal between the resistors to get a difference value of 2.5v or so then run same test see if it dips at 3k rpm still
Sorry but I must be missing something. Early in the video you effectively backprobed the sensor and showed that the 5V reference remained solid, and that the signal return voltage dropped inline with what the ECU was seeing. So didn't that rule out the ECU (at least this pressure sensor circuit) and the return wires. Why did you need to test the wires? Could something be actually commanding the vent solenoid on at 3000 rpm so what the sensor is seeing is actually correct? Or something else causing a loss of tank pressure at this RPM ? (I'm not real familiar with these systems).
mrNo the pressure in the tank couldn’t decay that quickly. Also 0-5v sensors almost never actually use that range. Expect around .7 to 4.2 normal operating range in my experience.
It could be a short to ground inside the tank. Maybe the pressure drop creates a short to ground inside the tank? If the fuel pump has to work faster then it could create that short too.
plastic tank so it can't short and the pressure sensor is in the plastic line not in the tank so it can't short to the tank and he cycled the purge solenoid at idle and the reading dropped like it should. it is when the rpm passes 3K that the signal return goes dead like it is shorting internally in the ecm. off camera he torqued up the drive line in gear and that did not effect it, it is purely rpm based.
Nicholas Bibeault He'd advise the client to sell the vehicle and buy a Toyota. "Modern caaars with all these electronics and computers - it's just plain stupid!"
I am not an auto mechanic, but it seems to me that you have proven that the problem is at the sensor, not the computer. I would hook up a hand vacuum pump to it, and see if it cuts out as you change the applied vacuum. If it does, change the sensor.
So the question is did Eric really ponder it during lunch? Is he pulling our chain? Could he be changing his style of diagnosis videos? Maybe Mrs O had his favorite meal ready? Or the guy with bad air showed up after conducting his own salt spray test on his wasted rims?
I have not come across any videos of you fixing a 2000/2007 ford focus.
Which I'm shocked about.
You're a smart. Smart ass. mechanic Who dumbs it down without making yourself sound dumb.
My car is having problems. I can't find the causing issue.
I'm just shocked you haven't had more of these focus come
That's why I stay tuned to your channel, because you're "REAL LIFE" no fake news, you bring real life experience to the front and center! Being a good technician/mechanic, is really hard work, and you have to be smart, and I've learned that experience brings wisdom. Thank you Mr. O.
Im looking fwd to watching this one. Love his lack of ego! Such a cool guy.
Eric , you are certainly a detective in diagnosing ANY vehicle trouble - it really is amazing the level of understanding you possess. Reading some of your bio - of how you grew up in your dad's shop ? Each and EVERY UA-cam video you make displays your IMMENSE Skills - for getting to the heart of the problem and locating the cause of failure. You indeed dig in - and run every possible test - to confirm your diagnosis - and , of course , this is the EXACT skill that places you in the preferred category of auto repair shops - YOU find and repair the problems many other shops cannot . I place you in the SUPER TECH category of technicians. You ARE that good - and I understand your , Mrs O , when she made the comment in your UA-cam video in which you repaired a shorted connector in her car ( one of your children spilled coke ) and it got into the connector, to the point - Mrs O said , you fix any vehicle you attempt to fix. AGAIN ,
THANK YOU MUCH for sharing your VAST knowledge of auto diagnosis and repair - I learn something from EVERY video you make and take a nugget of what you teach and place it in my own thought for diagnosing and repairing my personal vehicles. 👍👍👍✌️✌️✌️😊
A/c voltage? Check the diode pack. All kinds of nutty things happen with dirty voltage. My eye opener was a brake warning light that stayed on all the time. It was a Ford ranger.
Its really great watching you work the experience you bring to a job is something I work towards every day inspiring!
Eric from watching your videos I can tell you're a big fan of the classic reach around lol. You are one hell of a mechanic...its a shame more mechanics don't take pride in their work the way you do. God bless you and your family!
It is the most classic of all moves
I love these difficult diagnoses. It really shows how important troubleshooting skills are and that car repair isn't just connect up a Verus and fire the parts cannon!
The classic cliffhanger episode. I sure hope our superhero can save the day so life can return back to normal again.
Thanks again for your videos eric. Helping me loads in my mechanic training.
Now would be a great time to pull out that potentiometer from your AESWave backprobe kit, and use it to substitute for the pressure sensor. You can adjust it to get whatever value you want to see, and determine if the voltage still goes away at higher RPMs.
This is a strange one, for sure, but the ECM does actually seem to be reporting what it is seeing.
Yeah I was thinking way early in the video "stick a couple of resistors between 5v and signal, then signal and ground, then see if the behavior persists. If it does not, bad sensor (even though it seems really weird that such a thing is that predicatable).
You know what a failure is ? It's someone that won't try. I don't see that in you I see a fellow that gives everything he does 200% plus.... All your videos are always awesome praying for you always 😃👍👍👍👍👍👍
I LOVE your channel Eric. And these are the reasons why diag is one hour isn’t always correct and ANOTHER reason why service whiters have to have been in the field. I love your videos and just point blank your awesome and an inspiration on all levels! Thanks for the video a lot of fun
I won’t lie... my first thought was a leaky Canister Purge Valve.... love videos Mr. O. I can’t wait to see the epic conclusion to your conundrum.
"Super bizarre, super weird" These are good words to get me to watch the followup video. I'm IN! ~Mike
At last...your videos Eric makes my day :)
"Super Weird" Exactly what I think when something goes wrong with my truck. Nice to see you getting challenged. Don't forget the Brake Clean.
Well I WAS going to go to bed... it can wait. Thanks eric!
Hey Eric, why do you think about putting an ECM into it? It seems like the sensor itself does that. You checked the voltages at the fuel tank and they were corresponding with that you saw on the live data. You checked it being unplugged also, and it didn't do that. My suspicions goes to the sensor. I would recommend you open the gas cap and recheck it then. Don't want to say the evap valve opens and put the whole tank under great vacuum, but when the vacuum numbers would change, the sensor might react little different. Maybe it's a "dead spot" in the sensor like someone in the comments suggested, and opening the gas cap might prove that. Anyway, can't wait for part two, thanks Eric! :)
I love these kinds of diagnostic videos. No actron is gonna fix this puppy. Lol. Eric is going down the right path testing all the appropriate avenues to try and narrow the problem. Seems wierd that a ECM goes faulty just on Evap issues for these escapes. Is just one part of the internal circuitry bad?? Im leaning towards testing the fuel tank for leaks with the smoke detector machine. I mean if the trouble code is being set for an evap leak shouldnt we test for that first?? Why does it have to be an electrical problem out of the gate? I have no doubt Eric O will find the problem. Great step by step diagnosis.
I wish all mechanics were like him honest
Is that fuel pump duty cycle controlled? At a higher rpm and higher duty cycle increased vacuum in tank maybe?
I'd be more confident replace that sensor than the ecm. You proved the ecm is providing everything it needs to work and it didn't do it with a substitute signal. That right there makes me want to change the sensor
Hi man, great channel btw. I would disconnect the sensor from the ECU and plug it "standalone" to a 5v power supply and read the signal produced @3000 rpm. Keep up with the good work!
He showed the 5v reference that feeds the FTPS is the same 5v source that feeds the TPS and the DPFE and the anomaly wasn’t showing up in those two sensors, so that confirms that the 5vr signal coming from the ECU is okay. Supplying a standalone 5vr signal to the FTPS would probably not produce any different results. What I think is happening is there is some kind of vibration resonance frequency at 3k rpm that the FTPS doesn’t seem to like and so the voltage drop may be the result of an internal failure of the FTPS that only shows up at that frequency.
3000 rpm maybe getting vacuum into tank and sensor failing under vacuum or is the valve stuck closed allowing to much vacuum in the tank pulling it all the way down. This is a great video as always buddy keep up the great work. I wish I could watch all your live streams you have been doing. Can't wait for the next video
have a feeling this might be the same as out mazda tribute theres a tsb where charcoal canister will be contaminated by fuel and it would plug the vent. and have a faulty purge valve that opens at higher rpm causing a low voltage or creating huge negative pressure in your tank. check fuel trim numbers on your data pids. hope this helps.
Cool diagnosing i like those wire testers so far it seems to point the ecu I'll be looking forward to part 2 to see what you're discovered
I love the firehouse siren. We had the same type of siren in the small town I grew up in, in southwest Michigan.
Great stuff...I keep thinking, garbage in garbage out meaning the ECU seems to be working with values it's getting. I'm leaning toward sensor. They are so sensitive to begin any variable at 3k may trigger a glitch.
Thank Mr O, it's fun to follow along.
i would check the tank itself to see if at 3 k rpm the tank is somehow being put under a vacuum. and also testing the sensor resistance by itself under a 3krpm to see if it increases at 3 k to show an actual sensor voltage drop itself while disconnected from the harness on the sensor side. if it still has a voltage drop on the sensor side at 3k then my guess would be something fishy may be going on with the vacuum system , where somehow excessive vacuum is getting into the tank. but it is a severe instant voltage drop and not gradual.. so idk probably just rambling just a thought i had .
Boy that would have to be a very fast vacuum put on it to evacuate the tank that fast and I do not think it would pull it to zero volts because that is outside the operating range of that sensor ;)
Maybe the pressure really is being reduced at high rpm's if the tank isn't venting??. Small engines have that issue all the time. Can you remove the gas cap and see if it still does it?
The sensor will not pull down to 0 volts, not even if it had extreme vacuum, a functional sensor displays between 0.5V to 4.5V or even less. That is how the ECM can distinct shorts vs stuck low. It is a wicked short somewhere down the wire or perhaps ECM who can tell.
Mad4Tracks
correct
If you are getting the same wave form results at the sensor, why would you think its the ecm? Pop a new sensor in.
Hey Eric love your channel as always I'm leaning towards possibly a leaking purge valve
"Super Bizarre.." Oh yeah, a challenge for Dr. O!
Lmao.. The random tornado siren test makes this channel!!! 😆 Eric's Never phased or remotely acknowledges it. Ever! LOL...
I'd look for a nickle in the radio's cd player.
Erik: "so I think the next step is" and he's interrupted by the lunch siren and I found myself yelling out: 'lunch'!
I had a one where after the car ran awhile the the lights would start flashing like when someone sets the alarm. The higher the rpms went they would flash more. It wouldn't do it with the Alternator unhooked. It was a bad window motor/module shorted feeding voltage back to the BCM causing the lights to flash at higher rpms. That made me think of that.
Have you ever had the REAR DOOR LOCK MODULES SHORT OUT??? I took a 2004 Ford Escape to the Ford dealer 3 times. EVERY TIME THE VEHICLE GOT HOT FROM THE AIR TEMP OUTSIDE, THE FLASHERS WOULD ACTIVATE & THE HORN WOULD SOUND LIKE GABRIEL BLASTING HIS TRUMPET. ACCORDING TO MURPHY'S LAW A WATCHED POT NEVER BOILS. I let the dealer keep it and an hour after I left the ESCAPE DID IT'S THING AND THE MECHANIC FOUND THE BAD REAR DOOR LOCKING SENSOR. IT WAS REPLACED AND IT NEVER HAPPENED AGAIN.
I prefer PAUL'S AXIOM OF MURPHY'S LAW: YOU CANNOT FALL OFF THE FLOOR
Do you see why im looking for a three pedel car with a two knob radio, circa oh, 1968!
pull the sensor out of the tank and check to see if the problem is still there at atmospheric pressure without any variables of in tank pressure that should determine if it’s the sensor either way It looks like it needs a sensor at this point because even with a little in tank vacuum it should drop out
5:28 OMG! You see that orb float down from the top? Your shop is haunted!
Said no one. Hehehe
Ghost Busters are coming Monday and bringing the hackashack and we are gonna talk to the other side :)
Cliffhanger time... nice.
easy fix...... just go ask mrs. o what the problem is!
This is the difference between a mechanic or in your case a logical mechanic,and dealer fitters on menu rates,very good video,thanks.
I love a good mystery! Thanks for the video.
This is a cool diag so far Eric! I think you proved ECM and wiring integrity is OK. Maybe the sensor is not "linear" anymore? At this point I am curious to pull the FTP sensor out of the line and maybe manually put some pressure/vacuum on there... Does Keith already know what the problem is? xD
I think you will like part II, straight up Staten Island stuff haha and no Keith has never seen it before but he does know the answer now :D
Ivan you know what popped in my head also? Feedback into the pcm from a coil. That leakage we just learned about in Ziegler's class. You think a coil stress test would show anything?
Try different sensor
after wire verification checks
Coil feedback can definitely do funky stuff! Eric didn't see any voltage spikes on the 5V ref or signal wires at the sensor. However, a Vantage Pro set on a long timebase "graphing meter" setting can easily miss such quick events. I wanted to see a Pico on there :)
At the point when you’ve confirmed the sensor at the tank is acting independently of the 5V reference, my next move would have been to unplug the sensor and measure resistance or shermnangle a separate pressure gauge onto the tank. My inkling would be that it’s not lying.
wow...that hurt my brain just watching it. *scratching my head*
Not sure about the ford systems but i would do a check on evap purge/vent
Joe
Good one just needs more testing to isolate it. Some make you think outside the box or go back to basics but I'm sure you figured it out. You already figured out what triggered it and it's repeatable so the rest is a piece of cake :D
Ohhhhhhh just wait and see what the cause is... trust me it will make you want to quit working on cars, oh and FYI, it has nothing to do with the EVAP system or vacuum :)
I figured as much especially if it's from another system not even related...you have to have an open mind diagnosing nowadays. It's the head scratchers you wonder if you may have to ship it out broken but then it always comes to you...sometimes waking up at 3AM from a dead sleep and having to go to the shop right then to see if you're right and then have the police converge on your shop b/c they think you're breaking in...I've regressed that's another story :D
O I have been there wayyyyyy to many times at 3am haha. Your gonna like this one trust me. System not related is true but you won't believe what one lol
Hayward's Automotive to
My old man had one of these, he's so glad he got rid of it lol.
Eric O, my problematic 03 Mazda Tribute had the same issue. It threw a P0451 code, and changing the totally unrelated power steering switch cleared it.
Also would like to recommend re-test with alternator disconnected
Yes! Thank you! It might be nothing, but I've seen AC voltage from bad diodes in the alternator do all kinds of crazy stuff.
Gremlins are mischievous little devils. Much satisfaction when you catch them
At exactly 12:00 noon (NY time) when that air raid era siren goes off Eric didn’t flinch.
From my decades of EEC-IV experience, Ford uses the term "signal return" for the sensor low reference (ground), not for the signal itself, which is what you seem to be doing while thinking out-loud.
Disconnect the purge line from the vapor management valve redo the rpm test as rpm goes up volume flow goes up the normally open vent valve can compensate at idle not high rpm then make sure the canister isn't partially plugged have seen this on the f150 of that year I think their is a tsb on the f150
What about using your adjustable resistor to mimic your sensor and then use the scope to verify the pcm is dropping the voltage.
Can't believe ford put an access panel in there for the pump and evap
Good morning Sir. Good luck with that one!!!!
Love it nothing like a typical symptom to throw you for a loop
When I picked up my 01 Escape a month ago for $300, I had a hell of a time setting full readiness. Drove 200 miles and cat and evap hadn't set. Took 3 more days for evap to set because it was so warm outside here and the fuel tank wasn't at the right level... cat finally set though. Readiness is finicky in these cars, have to follow the drive cycle almost to the T
First thing that came to my mind was an internal short inside the sensor that is aggravated by vibration at that particular RPM. I don't really have enough experience with OBD-II to know if that's a common issue, or if it's even possible. I figure since there's a ground, and power (5v ref), it CAN possibly short internally. HMMM!! :)
Congrats sir!! Way to stick it out!
got it, fire the parts canon!!!!
it could be as simple as a faulty sensor, I would do the same test while the tank cap is open to make sure no pressure change effects the sensor , also measuring the Resistance while revving instead of the voltage while with the sensor disconnected, if it doesn't work I would connect a resistor that's similer to the sensor Resistance between 5v and and signal and do the same test if same problem occur I would check the ecu next,, good luck Eric we are waiting for part 2
Must have been the first Saturday of the month (in Michigan thats when they test the tornado sirens)
12:44 siren goes off. Haha. Got to love when that happens.
Can't wait for part 2. It's an interesting one
I don't know if it will help or not but I did notice that when you had the other sensor pids up they showed a small glitch at the same time as when the Fuel pressure sensor was dropping signal. I think looking at something inline with it somewhere might be worth a look. Could be another sensor that is on the same line that is RPM based could be causing an issue. That is my take on it. Probably wrong though.
Since the pressure sensor is essentially a pressure transducer... and with the testing you have done. If it is not the something wacky in the box, I would be suspect of a dead spot in the sensor at a certain vacuum or pressure. Can you get a vacuum gauge on the tank and see what the actual vacuum is at 3-4K RPM? Can you hook a vacuum pump on the sensor and see if you can reproduce the 0V reading at a certain vacuum or pressure. If it does go 0v at a certain pressure/vacuum, is that a normal range that should be in the tank? If not then the sensor may be working as designed and you may be seeing the effect of something else wrong in the EVAP/Fuel Delivery system.
Or just open the cap and rev it.
I suspect the FTP sensor as well. I think there's a worn section in the transducer that effectively opens the return circuit to the ECM. Thinking about it as if it were a throttle position sensor, it's likely that the beginning section of the internal contacts have been scrubbed excessively over 14 years of use, causing the issue. It happens at 3000 rpm because the ECM commands the purge solenoid open, and that vacuums the tank to the exact point where the circuit opens inside the FTP sensor. I've seen EVAP systems that open the purge solenoid above idle because the engine can tolerate the extra fuel vapors at that point without causing a drivability issue; if it happened at idle, the engine would surge and lope because of the extra fuel vapor going into the intake. I had the same idea as you, FrugalPrepper, to "bench test" the FTP sensor with a vacuum pump attached to see if the condition can be duplicated with the engine off. I always tend to suspect the component with moving parts first, because, by probability, it is more likely to fail than an ECM with no moving internal parts.
+1 sensor....vacuum pump time
When you showed the dpfe voltage trace there was a 'wiggle' at the same point in time as the voltage dropped off on the pressure sensor, so there is something in common with the other sensors.
My humble suggestion would be to disconnect the sensor from its pipe and repeat the test, this would confirm the above comments, maybe the vac suddenly changes at 3k due to the valve opening, old 90's rovers used to so something like this.
YES! This was exactly what I was thinking!
I think that EVAP purge valve between intake manifold and charcoal canister only opens at above 3,000 rpm so that the engine can cope with the addition of unmetered air. If the vent valve fails to open at this time to allow external air to flush out the canister then the tank will be subjected to intake vacuum and the tank pressure transducer will sense this.
Out on a limb (haven't watched part 2 yet)... open the gas cap and try again. My gut tells me the sensor is telling you the truth, and a vacuum is being pulled on the tank... real easy to check!
These escapes are really a mixed bag of surprises eh?
I would try the sensor itself maybe it was really over filled and the fuel compromised the sensor a flat spot of sort I know it's a long stretch but it is going to be the sensor or the pcm. It is a Ford they can be tricky.
Im along for the ride at 15 minutes. What I would have tried is taking the cap off the fuel tank, blocking the fuel tank filler trapdoor open so the tank is truly open to atmosphere, and repeat the test. I would want to know if the sensor was reporting accurate data.
Purge valve stuck open and vent valve restricted or stuck partially closed. Would be crazy if tps was at fault. Ive been running into some crazy stuff lately so who knows lol
Cool, But in this case I think you got that sensor in the act ;) The the small glitch at idle was the real give, and the un plug test - fuel tank pressure sensor is bad, cool that its right at 3k but my best guess is vibration, where is the tap test? ;) Cheers.
Maybe the tank is zero? At 3000 RPM could the purge valve be opening?
That was my immediate thought. As soon as the scope backed up the ECM readings, I would have started doing mechanical checks.
"Vintage Ford" Hah! making me feel old... Great video as always! Keep up the hard work and thank you for sharing your time with us. You are inspiring my friend.
Ford would more than likely recommend replace and recheck (All parts.? Carpet bombing). I would however wonder if the purge is sticking open slightly causing a vacuum only at 3k rpm...? (You were getting RPM surging when fussin' with that valve) Could try a vacuum gauge or transducer in place of the FTP sensor. Maybe the sensor and PCM aren't wrong. If that makes any sense. Keep us posted!!!
4stringbazooka Ha! I know, considering my newest vehicle is referred to as OBD zero by the maker.
That would have to evacuate the tank pretty quick to get it to drop to 0vdc....
You sir, are very correct! Even with the scanner refresh rate on the data that is a very sharp drop to 0 volts... However, I am kinda diggin' the idea of a defective sensor. Ford again would say "replace with known good and recheck". Not a huge fan of that idea. But, attempting a "bench test" on the FTP sensor would rule that out 100%. Dig out the ol' vacuum pump and make the "pressure" a more "controlled " variable. At the same time could hook up a vacuum gauge to the tank to see whats actually going on in there..? Just throwing ideas good and/or bad your way.
you should change the check engine light to a SMA light in all your customers cars . When the SMA light comes on get to your shop ASAP lol
love your videos!!
13:00 So this is when we COULDNT jump vref to sig rtn (to possibly produce a circuit high code) verifying circuit integrity being that its not like a potentiometer? Because no variable resistor? Just curious. Awesome video as always Sir.
Only other test I can think of is try a new sensor to check if it’s shorting under that specific load/vacuum. And you could also cut reference wire while leaving connector plugged into sensor to see if PCM is shorting it out under 3k rpm load, just shooting the sh*t with some ideas
On ford escapes if the customer tops the tank it will get liquid fuel in the return line , it sometimes takes awhile liquid to dissipate , in the mean time you have a code. Blow out the return line,reset codes should clear.
lol food is always good for the thought process!
From the tests you did, ground is good, 5V ref is good and the signal drops at 3K RPM. two things can do this in my opinion. Excessive vacuum in the tank. Not likely... or bad sensor. other option is to simulate a sensor reading with a resistor... But I suspect you need to replace that sensor...
LOL you say technically I say in theory keep up the good blogs
G'day, Mr. O! Well, take a break, and get some... Lunch!
Sharing: Just FYI, I have had three or four of these with this issue and have never been able to locate the exact point in the wiring where the problem is. This is after hours of monitoring power and ground and V.ref with the entire harness open and bending/flexing wires one at a time...
Pin 90 is reference voltage supplied by the PCM to several of the sensors. Unplugged it should have zero volts. Plugged in with the key on it should have 5 volts. It should never have battery voltage.
Cheers! :-)
Has to be a variable like vacuum, line noise or a drop in resistance in the Ecm. I would AMP clamp the return wire and the feed wire. Voltage is not your only thing to look at.
At work suddenly Eric show up
Great job again like always
Possible the sensor itself has become faulty and gone super sensitive so at higher rpms the vacuum registers higher than normal? What if you simulate a sensor with a couple resistors as a voltage divider connected to the 5v and ground and tapping into the signal between the resistors to get a difference value of 2.5v or so then run same test see if it dips at 3k rpm still
We know how you like a challenge. This is going to be a good one...or it will just be the component you suspect. I guess we'll see soon.
They say one step in diagnosing is to do the visual, I guess that includes checking all the pids on the scan tool.
Good one Mr O, could it be a anamoly with the pressure sensor? cheers sandy
Maybe... ;)
sandy anderson v,good opinion
sandy anderson agreed, plug in a known good sensor without installing in the tank and see what happens.
Sorry but I must be missing something. Early in the video you effectively backprobed the sensor and showed that the 5V reference remained solid, and that the signal return voltage dropped inline with what the ECU was seeing. So didn't that rule out the ECU (at least this pressure sensor circuit) and the return wires. Why did you need to test the wires? Could something be actually commanding the vent solenoid on at 3000 rpm so what the sensor is seeing is actually correct? Or something else causing a loss of tank pressure at this RPM ? (I'm not real familiar with these systems).
@John Griffin, i tkink you are close, but it is only in Park !! So i think there is a short in some cable loom where the Park lines run too.
Why is it so hard to accept that the problem is inside the tank or some of the lines?
mrNo the pressure in the tank couldn’t decay that quickly. Also 0-5v sensors almost never actually use that range. Expect around .7 to 4.2 normal operating range in my experience.
It could be a short to ground inside the tank.
Maybe the pressure drop creates a short to ground inside the tank?
If the fuel pump has to work faster then it could create that short too.
plastic tank so it can't short and the pressure sensor is in the plastic line not in the tank so it can't short to the tank and he cycled the purge solenoid at idle and the reading dropped like it should. it is when the rpm passes 3K that the signal return goes dead like it is shorting internally in the ecm.
off camera he torqued up the drive line in gear and that did not effect it, it is purely rpm based.
OMG.. 20 years in the business and i STILL get a diag every now and again that has me going in circles.. that's when we strip that lease return.. Lol
good article in motorage!!!
I really hope that's not Scotty Kilmer hanging out on your whiteboard there. Do you ever get a tricky diag like this and wonder WWSKD?
Nicholas Bibeault He'd advise the client to sell the vehicle and buy a Toyota. "Modern caaars with all these electronics and computers - it's just plain stupid!"
your the best Eric
I am not an auto mechanic, but it seems to me that you have proven that the problem is at the sensor, not the computer. I would hook up a hand vacuum pump to it, and see if it cuts out as you change the applied vacuum. If it does, change the sensor.
So the question is did Eric really ponder it during lunch? Is he pulling our chain? Could he be changing his style of diagnosis videos? Maybe Mrs O had his favorite meal ready? Or the guy with bad air showed up after conducting his own salt spray test on his wasted rims?