A simple "check engine light" diagnosis turns out to be film-worthy! Join me for the diagnosis of this '09 Chevy Cobalt with 92k miles on the odometer.
I'm not a mechanic but I do know a lot of stuff about cars. Compression ratios should be 10-15% within range of each other. Cylinder 1: 210 Good Cylinder 2: 210. Good Cylinder 3: 120. Alright Cylinder 4: 210. Good Take 120, divide that by 210, then multiply that by 100, and you'll get your percentage. According to my math, 120 is 57.14% (Rounding it down) so, that's 57% decrease in compression. So, Cylinder 3 definitely has a misfire. You can try two things. If you pour oil and the compression goes up, then it's bad rings. If the compression goes down, then you have a valve problem, scored cylinders, head gasket leak, or a blowby. I hope this helps bro! :D
I'm proud of you. Most of the wanna be techs here on You Tube don't have a clue about shop safety or the four stroke process whatsoever. Someone invested a great deal of time and patience training you and it shows. Bravo & KUTGW! Master Tech PARSR
Thanks for the comment! Back in 2004 my friend and I picked up a free 1981 Yamaha XS400 motorcycle that was set out for scrap metal. The engine turned over, so we were curious if we could get it running again. We poured in a gas-oil mix because I thought all small motorcycles were two-strokes haha. Then we got a Chilton's Repair manual and started reading...that was the beginning of my "training". A background in physics and engineering was very helpful, but I have no formal automotive training at all...just a strong passion!
This is an awesome video! As a Chevy technician that drives an 08 Cobalt and has the SAME exact issue, I did most of the same diagnostics as done in this video but I did NOT use the fancy scan tool (too damn broke to afford one of those lol). I just did a standard compression test across all cylinders (wet and dry). This is a SUPER common issue with the 2.2 and 2.4 engines, mostly the 2007-2009 L61's (Gen-II revision). Only way to fix the issue is to have the head refinished or replaced entirely. As a fellow technician I really enjoyed this video. Subbed, keep up the fantastic work!
@Jonathan A well mines its hard to explain but long story short i had the car half way on and i try to start it but its was dead i jump it and a ugly noise came on and was jumping i turn it off and back on it was working fine till i get to a friend's house stayed there maybe a hr and my car would not start battery works i try to crank it one more time it didn't start and the noise comes back i turn off the car its still going for 5 minutes at this point something smelled burnt the noise was getting low and lower till it shorten out the battery ..i jumped it now and discounted the negative if i put it back on it makes a low nosie if i can try to send you a video any kind of way to show you i dont want to get ripped off
mrexecutive1 I guess I was one of the lucky ones. My 05 Cobalt with the 2.2 never had this issue I did trade it in for a Camaro at 80,000 miles, but it still ran fine.
I have the same leak in cylinder 2. Im driving like that an the transmission sounds very bad when stop in traffic. At 11200 miles still worth the money to rectify the head.
Thanks! It sounds like, based on this video, my next test is leak down on my missing cylinders, 1 & 4. I was leaning towards leaking exhaust valves but after this I am willing to bet it!
Firstly: you've made a very thorough and professional diagnosis as well as a well made, educational video. Thank you sir. You really seem to know yer way around an engine. I've got an '09 cobalt with a manual transmission that revvs to around 4500 rpms over and over for the first 5 minutes and then bucks at the top end of every gear. Also accompanied with the smell of gasoline but old stanky gasoline. Any idea's or nudges in the right direction would be greatly appreciated.
I have the same exact issue and the same car as you! in 3rd and 4th gear at cruising speed the car will sputter and buck and shake. I don't think our issue is a misfire, my guess is something with ignition or fuel/vacuum. I replaced the mass air flow sensor, coils & spark plugs, cam shaft and crank shaft sensors, 2 oxygen sensors, the evap solenoid valve, catalytic converter, throttle body, fuel filter, and still the problem continues. The exhaust does smell terrible, like a sulfur fire cracker smell. Also my miles per gallon dropped all the way down to 15mpg on the highway at 65-70mph. did you every figure out what was wrong with yours?
Sad to say, I did not. It was costing me more time and money than I could part with. I sold it for scrap and used the money towards a new transmission in my ford. @@tylerdurden9748
hllywd964 first time watching video of him and imma tell you that I’m filling now I never like math but the way he’s doing it to me it’s very impressive and I like that, this young fella knows what he doing!
missfire makes exhaust sound like theres a exhaust leak somewhere but its the missfiring causing that. i had case on a 99 expedition 1and 8 coils were swaped by previous owner. the scanner said 8 was missfiring. i checked 1 coil and that was good but bolt hole was broke so it got renewd. 8 was bad with crazy ohm readings on the coil pins and one of the pins was burnt thats the one giving crazy readings. looked like a old coil was put in. put the new one in and now its fine no miss. dont know if the coil was put in with a burnt pin or the connector burnt it. if it starts again then its the connector burning coil pins. we'll see.
I had a P0300 code on my 2006 chevy cobalt. Engine misfire. That code has a few reasons to come on but the main and most likely reason is spark plugs. I put new A/C spark plugs in and the code has been gone. Plus it runs like a new car with 178,000 miles.
The compressed air test is a very handy test in pinpointing the cause of the problem. Wonder why the relative compression test was not accurate ? Is a compression test the quickest way to nail a misfire ? Would you not have gone after the spark and the coils ?Can't wait for the teardown.
+Tom OConnor The cylinder drop test showed that #3 was contributing, just not as much as the others. That alone suggested that combustion was occurring, so the coil and plug were most likely OK. Also the quick "crank and listen" test led me toward a mechanical problem.
So correct me if I'm wrong, Ivan, but to do a leak down test do you necessarily have to be at TDC on the cylinder? I thought you just had to make sure BOTH valves were closed. That happens at other times than just TDC in the cycle, doesn't it?
Both valves are only fully closed when at TDC at the end of the compression stroke. TDC at the end of the exhaust stroke, the valves are almost closed but not fully
Hi, thanks for a great video. Looks like I got the same problem with my 2006 Cobalt. Cyl 3 misfire and low compression in 3rd cylinder. Turns out it's pretty costly mechanic repair. How long can I live with that issue? Is it super urgent repair?
Ivan did you see what the bad cylinder looked like with your pressure transducer? Be a good learning experience for everyone on compression waveforms. Pretty cool you were using math to figure out your compression from your starter current.
Can't rule out DIY valve adjustment done wrong. But I don't know this engine or if that's a possibility even. Pet peeve of mine since I've run several old school VW air cooled and on those you adjust the valves with EVERY 3,000 mile oil change or build a lot of spare engines. Sister's 96 Honda has such loud valve noise the techs that have been in there before must be using .012 instead of .004 - insane. On to the solution.
My cobalt put out a po300 I changed my fuel pump and misfire went away. I noticed mileage drop from 22 to 14 started having misfire code was there. It felt like fuel pump.
+motoYam82 I do a lot of work here in Scotland on LPG (Autogas) vehicles and we do run into valve seat problems now and again. Usually its valve seat wear giving zero or worse valve clearance, when in doubt now and on suitable vehicles I will remove inlet manifold and test with some diesel at the back of the valves and bring the piston to TDC compression, major frothing all round the valve means trouble.
this is off topic, but I wanted to ask you since we're both in a similar business. How do you deal with customers that want to hang around over your shoulder while you're working? I personally can't stand it and feel like they're being quite rude. I also do know how to tell them to let me do my job in a nice way. Do you have any feedback or advice for me? Thank you.
It depends on the customer. If it's a good friend I don't mind them hanging out. Otherwise I say "This is a really tough problem so I need to focus so I don't have to charge you for an extra hour" lol
motoYam82 good idea. Guess it's how you say it really. i get frustrated when they hang over and keep asking did you figure it out yet or what's this or that? honestly they even annoy me when they stand and don't say anything. most customers aren't like that but the ones that are really ruin my day.
Hey Ivan, loved this vid, just started pulling the head on my 2009, same problem but #4. What do I need to buy new for the r&r. Head bolts, thermostat, ??? Thanks!
I have a 2006 Chevy Cobalt 2.2 L for the misfire on cylinder 1. It happens every year sick and tired of this car just want to sell! I replace all the parts every yeah from anywhere from the coilpacks, all the tires brakes. I hate this car I paid $700. For this car and spent way over $2000. every year. I just want a truck with no more computer problems anymore. What ever happened to cars from back in the days that had no computer's in it. LOL I guess I got what I paid for.
I have a question for Pine Hollow Auto Diagnostics. My Cobalt 2007 2.2 is doing the same, hesitates to start, shakes and turns off, it gets worse after I finish fueling, I have to pump the gas pedal for it to start and keep accelerating if not the revolutions go down and turns off. Is this video the same case as mine? Any suggestions to fix the problem?
Thank you for answering. I replaced it like 9 months ago and after that my car kept doing the same after fueling, but now smells like burn after a hesitated and shaking start, I changed the exhaust system, did a tune up and coil changes, the electric mechanic tested and its not a sensor, it says misfire cylinder No.2 P0302
If it wasn't your EVAP and it's still going rough and stalling sounds like your cobalt throttle body is dirty. I found a video on YT how to clean it. Not a hard fix and clean. Make sure you disassemble it from your car because you can 1) Upset the computer while moving the body while it's still attached to the car 2) It holds a powerful charge and is built to actuate ice so it can possibly take your finger off. DISCONNECT IT. Once off spray it will Throttle Body Cleaner and scrub! It will be like a new car! This is the video I watched ua-cam.com/video/JPNnHU6PYbo/v-deo.html also here is a picture of my dirty throttle body instagram.com/p/BYzLyyjHDFf/ before cleaning it. NOTE: This made the car run WAY better but did not get my misfire off. Hope this helps anyone dealing with this issue.
One theory I've read online is that a faulty injector causing a lean mixture on a cylinder, which burns hotter and deforms the valve seats...I don't know if that's the case here, but might have to do an injector balance test after it's back together!
+motoYam82 Ivan I called my friend and he's saying the opposite ,its not lean he's saying not to take the head off , what he's finding is carbon buildup on the back of the valves building up and to decarbonize the engine. Hope this is your situation . Take care
+Andres Ospina Well it's not really voltage, he's measuring amperage on a goofy volt scale so if I'm not mistaken, the 1.88 "volts" is really 188 amps. It's also not really an equation in the sense that I think you are asking - what he's really doing is figuring out the ratio of "volts" to psi on a good cylinder and comparing that to bad one, i.e. V_good/PS_Good = V_bad/PS_Bad. So if you know the good voltage, the bad voltage, and the good psi, then the bad psi is simply v_bad/v_good/ps_good. Which in this case was actually really far off. It's mostly a parlor trick though - if you had a compression gauge I don't think you'd ever rely on the amperage difference between cylinders alone - you'd take a real pressure measurement.
+Andres Ospina There's no magic formula here. Basically the amperage of the starter current is proportional to the power needed to turn over the engine. The humps are occurring during the compression stroke as the load on the starter increases. All we can really say here is that if a hump is lower than the others, then the mechanical resistance of that particular piston is less than the others. Like Ken said below, looking at a simple ratio (Amps to psi) can provide a very rough estimate of how much the compression varies. It may be more accurate to measure the amplitude of the humps not from 0 like I did here, but from the low points on the waveform. So if one hump is 20A low to high, and another is 40A, then the compression is roughly double :)
Well, I guess it will be while before you can hire your own cameraman, huh? Seriously, a wide angle camera and tripod at strategic location should do it. Almost every youtube automotive star tries his best NOT to give vertigo his viewers. To grow your subscribers, this is something you really need to look in to.
8track Abraham I had an 05 and the only issue relatively close was an oxygen sensor that went out. I took it all the way to 80,000 miles and traded it in for a 15 Camaro, it still ran fine.
motoYam82 yeah, I feel pretty confident that if I still had it, I wouldn't have had this issue, but I guess it can't be guaranteed either way. I was just ready for a change.
I have an 08. Cobalt ...and an 08 G5 .!Never an issue. PREVENTATIVE maintenance is key ..30K.50K.90K ROUTINE MAITENANCE WOULD HAVE PREVENTED ANY FAILURE...THE CAR ISNT THE ISSUE ITS THE drivers...lmao
![Lp. Сердце Вселенной #1 НАЧАЛО ПУТЕШЕСТВИЯ [Новый сезон] • Майнкрафт](http://i.ytimg.com/vi/380Q7gLWGvk/mqdefault.jpg)
I'm not a mechanic but I do know a lot of stuff about cars.
Compression ratios should be 10-15% within range of each other.
Cylinder 1: 210 Good
Cylinder 2: 210. Good
Cylinder 3: 120. Alright
Cylinder 4: 210. Good
Take 120, divide that by 210, then multiply that by 100, and you'll get your percentage.
According to my math, 120 is 57.14% (Rounding it down) so, that's 57% decrease in compression.
So, Cylinder 3 definitely has a misfire. You can try two things. If you pour oil and the compression goes up, then it's bad rings. If the compression goes down, then you have a valve problem, scored cylinders, head gasket leak, or a blowby.
I hope this helps bro! :D
Could a collapsed hydraulic lifter or two give you the same symptom and low compression on that 1 cylinder?
I'm proud of you. Most of the wanna be techs here on You Tube don't have a clue about shop safety or the four stroke process whatsoever. Someone invested a great deal of time and patience training you and it shows. Bravo & KUTGW!
Master Tech PARSR
Thanks for the comment! Back in 2004 my friend and I picked up a free 1981 Yamaha XS400 motorcycle that was set out for scrap metal. The engine turned over, so we were curious if we could get it running again. We poured in a gas-oil mix because I thought all small motorcycles were two-strokes haha. Then we got a Chilton's Repair manual and started reading...that was the beginning of my "training".
A background in physics and engineering was very helpful, but I have no formal automotive training at all...just a strong passion!
I'm impressed! Being a home mechanic I've never see this process done before. I guess you do learn something every day. Thanks Ivan!!
This is an awesome video! As a Chevy technician that drives an 08 Cobalt and has the SAME exact issue, I did most of the same diagnostics as done in this video but I did NOT use the fancy scan tool (too damn broke to afford one of those lol). I just did a standard compression test across all cylinders (wet and dry). This is a SUPER common issue with the 2.2 and 2.4 engines, mostly the 2007-2009 L61's (Gen-II revision). Only way to fix the issue is to have the head refinished or replaced entirely.
As a fellow technician I really enjoyed this video. Subbed, keep up the fantastic work!
@Jonathan A have you fixed this just happened to me help?
@Jonathan A well mines worse it makes noise while its off
@Jonathan A well mines its hard to explain but long story short i had the car half way on and i try to start it but its was dead i jump it and a ugly noise came on and was jumping i turn it off and back on it was working fine till i get to a friend's house stayed there maybe a hr and my car would not start battery works i try to crank it one more time it didn't start and the noise comes back i turn off the car its still going for 5 minutes at this point something smelled burnt the noise was getting low and lower till it shorten out the battery ..i jumped it now and discounted the negative if i put it back on it makes a low nosie if i can try to send you a video any kind of way to show you i dont want to get ripped off
@Jonathan A the key was out the car noise coming from hood and smelled burnt and a little smoke came out
@Jonathan A its crazy i know ill update you I'm working on it. now
Common issue on GM 2.2l and 2.4l 2005-09 leaky exhaust valve seat. Had this experience with a Chevy HHR. Nice diagnostic strategy, very efficient!
+mrexecutive1 SO what's the correct long-term fix??
Replace or refurbish cylinder head.
mrexecutive1 I guess I was one of the lucky ones. My 05 Cobalt with the 2.2 never had this issue I did trade it in for a Camaro at 80,000 miles, but it still ran fine.
mrexecutive1 I have a 2010 I've been throwing the parts cannon at and I have a persistent cly 4 misfire, I'm fearing i have a leaking valve.
I have the same leak in cylinder 2. Im driving like that an the transmission sounds very bad when stop in traffic. At 11200 miles still worth the money to rectify the head.
Dude, you are the man. This was some impressive stuff dude.
Thanks! It sounds like, based on this video, my next test is leak down on my missing cylinders, 1 & 4. I was leaning towards leaking exhaust valves but after this I am willing to bet it!
Great video, excellent work up testing and diagnosing the problem.
A demonstration of skill. Thanks Ivan.
Firstly: you've made a very thorough and professional diagnosis as well as a well made, educational video. Thank you sir. You really seem to know yer way around an engine.
I've got an '09 cobalt with a manual transmission that revvs to around 4500 rpms over and over for the first 5 minutes and then bucks at the top end of every gear. Also accompanied with the smell of gasoline but old stanky gasoline. Any idea's or nudges in the right direction would be greatly appreciated.
I have the same exact issue and the same car as you! in 3rd and 4th gear at cruising speed the car will sputter and buck and shake. I don't think our issue is a misfire, my guess is something with ignition or fuel/vacuum. I replaced the mass air flow sensor, coils & spark plugs, cam shaft and crank shaft sensors, 2 oxygen sensors, the evap solenoid valve, catalytic converter, throttle body, fuel filter, and still the problem continues. The exhaust does smell terrible, like a sulfur fire cracker smell. Also my miles per gallon dropped all the way down to 15mpg on the highway at 65-70mph. did you every figure out what was wrong with yours?
Sad to say, I did not. It was costing me more time and money than I could part with. I sold it for scrap and used the money towards a new transmission in my ford.
@@tylerdurden9748
Very nice diagnosis. Looking forward to part two.
Pretty cool diagnosis, the uneven cranking sound gives good direction, looking forward to p2 and 3 maybe!
Wow good job... Ur a wizard on that snap on machine... I cant get my head round that thing.... Cheers:
Nice job...I noticed on some of your other videos how you utilize your math skills...Impressive...
hllywd964 first time watching video of him and imma tell you that I’m filling now I never like math but the way he’s doing it to me it’s very impressive and I like that, this young fella knows what he doing!
good job Ivan, waiting for part two.
Thank you for a well thought out diagnosis
I threw some engine restore in my 06 cobalt and it fixed my compression issue
That was really awesome and informative.
Great video! Thanks. Really enjoy the diagnosis videos.
Very cool. It will be interesting to see what's going on.
Great diagnosis Ivan.
Great video. Very nice work.
missfire makes exhaust sound like theres a exhaust leak somewhere but its the missfiring causing that. i had case on a 99 expedition 1and 8 coils were swaped by previous owner. the scanner said 8 was missfiring. i checked 1 coil and that was good but bolt hole was broke so it got renewd. 8 was bad with crazy ohm readings on the coil pins and one of the pins was burnt thats the one giving crazy readings. looked like a old coil was put in. put the new one in and now its fine no miss. dont know if the coil was put in with a burnt pin or the connector burnt it. if it starts again then its the connector burning coil pins. we'll see.
Thanks for posting. Sounds like you can probably get away with just removing the cylinder head replacing the exhaust valve depending on mileage?
I had a P0300 code on my 2006 chevy cobalt. Engine misfire. That code has a few reasons to come on but the main and most likely reason is spark plugs. I put new A/C spark plugs in and the code has been gone. Plus it runs like a new car with 178,000 miles.
Well.... Another day at school!!!
Thanks
The compressed air test is a very handy test in pinpointing the cause of the problem. Wonder why the relative compression test was not accurate ? Is a compression test the quickest way to nail a misfire ? Would you not have gone after the spark and the coils ?Can't wait for the teardown.
+Tom OConnor The cylinder drop test showed that #3 was contributing, just not as much as the others. That alone suggested that combustion was occurring, so the coil and plug were most likely OK. Also the quick "crank and listen" test led me toward a mechanical problem.
Danner has taught u well young man
enjoyed the diagnosis. I'm buying a stethoscope to help diagnose problems with appliances.
+Randy Gudeahn (ProTech) It's a great tool to pinpoint squeaks, rattles and air leaks for sure!
Nice work Ivan...
Nice quick diagnosis
Great diagnostics!
Mismo problema en mi cobalt 2007 gracias por esa solusion
Yet another gread vid. Will be interesting to see what's messed up in the head :)
I wonder if using sea foam to clean the valves first would be a good idea
Nice job troubleshooting
2008 chevy cobalt owner found this video from having this problem with my car
Muy bien, buen diagnóstico.
Great diagnose. Could be carbon around the exhaust valve. I would have tried a cheap fix like seafoam.
So correct me if I'm wrong, Ivan, but to do a leak down test do you necessarily have to be at TDC on the cylinder? I thought you just had to make sure BOTH valves were closed. That happens at other times than just TDC in the cycle, doesn't it?
Both valves are only fully closed when at TDC at the end of the compression stroke. TDC at the end of the exhaust stroke, the valves are almost closed but not fully
Didn't know how to find TDC, Thanks. How does the scope compute compression? I thought the compression guage was the only way.
Hi, thanks for a great video. Looks like I got the same problem with my 2006 Cobalt. Cyl 3 misfire and low compression in 3rd cylinder. Turns out it's pretty costly mechanic repair. How long can I live with that issue? Is it super urgent repair?
eh not really urgent...live with it until it gets annoying :)
Красивый пейзаж , если смотреть от ворот гаража.
Ivan did you see what the bad cylinder looked like with your pressure transducer? Be a good learning experience for everyone on compression waveforms. Pretty cool you were using math to figure out your compression from your starter current.
+busjockey1 Of course. Part 2 is just for you!
Cool can't wait to see it. I am a big fan of using pressure transducers, love my wps 500
Be interesting to see under the valve cover . But seems a few of those engines do have exhaust valve issues
That it would. White board, what would cause an exhaust valve leak here: Broken valve spring, bad valve/seat, valve hanging up
+wtbm123 Part 2 should be up soon :)
Nice. Broken valve spring usually ends up with 0 compression
Can't rule out DIY valve adjustment done wrong. But I don't know this engine or if that's a possibility even. Pet peeve of mine since I've run several old school VW air cooled and on those you adjust the valves with EVERY 3,000 mile oil change or build a lot of spare engines. Sister's 96 Honda has such loud valve noise the techs that have been in there before must be using .012 instead of .004 - insane. On to the solution.
hydraulic lash adjusters here, but I guess you could have one that sticks...
What was the car doing cause I have a 2010 cobalt no check engine light and it’s surging at 25 mph and 40 mph idk what’s happening
exelente diagnostico grasias
Im guessing exhaust valve seal caused by weak spring.
that was amazing. I don't trust mechanics and now i know i should lol. Wow your so smart. How much was the total repair after all was said and done?
when did you get the Autel? do you like it?
ivan is awsome! thanks buddy
Hi before you start that it's supposed to be spark plug gap set I know
What's up with the Autel ? Great detective work Ivan ! Fast and efficient !
+Billy R IDK what's up with the Autel? Can't let the Verus hog all the attention :)
My cobalt put out a po300 I changed my fuel pump and misfire went away. I noticed mileage drop from 22 to 14 started having misfire code was there. It felt like fuel pump.
Just measure fuel pressure 👍
There would be a base current for the engine cranking with all plugs out, that might skew the calculation.
+Niall Seddon Great point, Niall. I have to experiment some more on different vehicles to see if we can develop a more accurate amps-to-psi relation.
+motoYam82 I do a lot of work here in Scotland on LPG (Autogas) vehicles and we do run into valve seat problems now and again. Usually its valve seat wear giving zero or worse valve clearance, when in doubt now and on suitable vehicles I will remove inlet manifold and test with some diesel at the back of the valves and bring the piston to TDC compression, major frothing all round the valve means trouble.
do have the repair manual so i dont mess up timming and or varriable valve timming
Is there a best case scenario when you did the leak down test, or was it always going to be head off, skim, new gasket, valves etc
+Typey1 There's never a best-case scenario if it comes to the leak-down test lol
this is off topic, but I wanted to ask you since we're both in a similar business. How do you deal with customers that want to hang around over your shoulder while you're working? I personally can't stand it and feel like they're being quite rude. I also do know how to tell them to let me do my job in a nice way. Do you have any feedback or advice for me? Thank you.
It depends on the customer. If it's a good friend I don't mind them hanging out. Otherwise I say "This is a really tough problem so I need to focus so I don't have to charge you for an extra hour" lol
motoYam82 good idea. Guess it's how you say it really. i get frustrated when they hang over and keep asking did you figure it out yet or what's this or that? honestly they even annoy me when they stand and don't say anything. most customers aren't like that but the ones that are really ruin my day.
Hey Ivan, loved this vid, just started pulling the head on my 2009, same problem but #4. What do I need to buy new for the r&r. Head bolts, thermostat, ???
Thanks!
I just got a FelPro top end gasket set...good luck!
I have a 2006 Chevy Cobalt 2.2 L for the misfire on cylinder 1. It happens every year sick and tired of this car just want to sell! I replace all the parts every yeah from anywhere from the coilpacks, all the tires brakes. I hate this car I paid $700. For this car and spent way over $2000. every year. I just want a truck with no more computer problems anymore. What ever happened to cars from back in the days that had no computer's in it. LOL I guess I got what I paid for.
awesome
I have a question for Pine Hollow Auto Diagnostics. My Cobalt 2007 2.2 is doing the same, hesitates to start, shakes and turns off, it gets worse after I finish fueling, I have to pump the gas pedal for it to start and keep accelerating if not the revolutions go down and turns off. Is this video the same case as mine? Any suggestions to fix the problem?
Your EVAP purge solenoid is stuck open. Replace it. Use ONLY OEM DEALER item!
Thank you for answering. I replaced it like 9 months ago and after that my car kept doing the same after fueling, but now smells like burn after a hesitated and shaking start, I changed the exhaust system, did a tune up and coil changes, the electric mechanic tested and its not a sensor, it says misfire cylinder No.2 P0302
If it wasn't your EVAP and it's still going rough and stalling sounds like your cobalt throttle body is dirty. I found a video on YT how to clean it. Not a hard fix and clean. Make sure you disassemble it from your car because you can 1) Upset the computer while moving the body while it's still attached to the car 2) It holds a powerful charge and is built to actuate ice so it can possibly take your finger off. DISCONNECT IT. Once off spray it will Throttle Body Cleaner and scrub! It will be like a new car! This is the video I watched ua-cam.com/video/JPNnHU6PYbo/v-deo.html also here is a picture of my dirty throttle body instagram.com/p/BYzLyyjHDFf/ before cleaning it. NOTE: This made the car run WAY better but did not get my misfire off. Hope this helps anyone dealing with this issue.
Lol,well done my friend
Nice one 👍👍
+Steve Rob Hey Steve you wouldn't know if this thing would be covered under warranty? It's a 2009 with 92k miles...
No ivan its past the time but i can ask what the fix is at the dealership. My daughter has the same car. Never had a problem.
One theory I've read online is that a faulty injector causing a lean mixture on a cylinder, which burns hotter and deforms the valve seats...I don't know if that's the case here, but might have to do an injector balance test after it's back together!
+motoYam82 Ivan I called my friend and he's saying the opposite ,its not lean he's saying not to take the head off , what he's finding is carbon buildup on the back of the valves building up and to decarbonize the engine. Hope this is your situation . Take care
Thanks for the info Steve! Head's already off; Part 2 will be out tomorrow morning :)
Stretched timing chains are another popular feature on those ecotecs.
scannerdanner had a cobalt that they couldnt find the problem maybe its the same problem.
Chevy Cobalt? Well THERES your problem!
wysetech2000 runs for more popcorn for part two.
Ivan what's the math equation for the volts to psi
+Andres Ospina
Well it's not really voltage, he's measuring amperage on a goofy volt scale so if I'm not mistaken, the 1.88 "volts" is really 188 amps.
It's also not really an equation in the sense that I think you are asking - what he's really doing is figuring out the ratio of "volts" to psi on a good cylinder and comparing that to bad one, i.e.
V_good/PS_Good = V_bad/PS_Bad.
So if you know the good voltage, the bad voltage, and the good psi, then the bad psi is simply v_bad/v_good/ps_good. Which in this case was actually really far off.
It's mostly a parlor trick though - if you had a compression gauge I don't think you'd ever rely on the amperage difference between cylinders alone - you'd take a real pressure measurement.
+Andres Ospina There's no magic formula here. Basically the amperage of the starter current is proportional to the power needed to turn over the engine. The humps are occurring during the compression stroke as the load on the starter increases.
All we can really say here is that if a hump is lower than the others, then the mechanical resistance of that particular piston is less than the others. Like Ken said below, looking at a simple ratio (Amps to psi) can provide a very rough estimate of how much the compression varies. It may be more accurate to measure the amplitude of the humps not from 0 like I did here, but from the low points on the waveform. So if one hump is 20A low to high, and another is 40A, then the compression is roughly double :)
Thank s Ivan for your time
In my case it was simply the coil pack
You seem a doctor, you just need a gown =)
LOL
haha that was good :)
Interesting because I have an '09 Cobalt with a cylinder 3 misfire. Fucking lemon cars.
dchen345 my 09' cobalt has a cylinder 1 misfire. Compression was bad. It's in the shop as we speak :(
I have an 09 cobalt that has a surging idle, I wonder if its the same thing...
I have a 2010 misfire on cyl 4
Great video but you really need to invest in a tripod!
+12vgs8606 I have one. But it's the base model and can't follow me around on its own too well :)
Well, I guess it will be while before you can hire your own cameraman, huh? Seriously, a wide angle camera and tripod at strategic location should do it. Almost every youtube automotive star tries his best NOT to give vertigo his viewers. To grow your subscribers, this is something you really need to look in to.
Yea you. Did. Hand up. Smack
Weiil atleast you know the Rings are OK...
Your calculation didn't work because it's not linear. It's more of a logarithmic calculation I would bet.
they made those engines really crappy
8track Abraham I had an 05 and the only issue relatively close was an oxygen sensor that went out. I took it all the way to 80,000 miles and traded it in for a 15 Camaro, it still ran fine.
You would hope that it would run OK for at least 80k miles!
motoYam82 yeah, I feel pretty confident that if I still had it, I wouldn't have had this issue, but I guess it can't be guaranteed either way. I was just ready for a change.
I have an 08. Cobalt ...and an 08 G5 .!Never an issue. PREVENTATIVE maintenance is key ..30K.50K.90K ROUTINE MAITENANCE WOULD HAVE PREVENTED ANY FAILURE...THE CAR ISNT THE ISSUE ITS THE drivers...lmao
Yikes!!! LOL
The car is a piece of garbage. 💨💨💨💨💨💨💨💨💨
Hi before you start that it's supposed to be spark plug gap set I know