Fox Mustang TPS Glitch Causes High Idle
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- Опубліковано 5 жов 2024
- In this episode, we explore a hanging idle issues observed by Paul Ritchie. While idling, the car suddenly jumps up in RPMs with out touching the throttle pedal at all. What went wrong?
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Great video, I could have used this earlier this year when I was at the end of my tether with the same high idle problem on mine. The problem I had diagnosing is that I'd not long replaced the TPS and so immediately ruled it out in favour of connectors, ECM etc when I shouldn't have done. I didn't have the tech to do what you did here so instead mounted my multimeter on the dash, wired it through to the TPS wires and then monitored the voltage whilst driving. I was able to watch the voltage dip way below the baseline taken at startup and then immediately the idle would go up.
I replaced the TPS and it's been fine ever since. Moral of the story being the quality of some aftermarket sensors is not always as good as it should be!
Glad this helped you. And we agree about the sensors today often being garbage. We are working on a sensor testing rig that can be used to verify sensor functionality before the sensors go out the door. We hope to start selling tested/calibrated sensors in the next few months. Likely starting with coolant temp, then air temp, then TPS. Not sure we will be able to do much on oxygen sensors though.
Yet another great and highly educational video!
Awesome Matt...
Your expertise never fails to impress...
Missed you for a couple of weeks...
Hope all is well...
Busy busy busy! Lol. Got more stuff coming soon though. My Holley terminator x showed up yesterday.
I have a had a similar issue. I think the tps voltage jumped up and then back down in almost a continual pattern. So a little different than here but still may apply. Ended up being the capacitor in the ECM went bad.
Good to know. Haven’t run into that before, but when the caps are bad, I’d say all bets are off. Lol.
TPS's are POTs, definitely time to replace
Another informative video!
Hey just want to say thx I found your channel from brew2L live stream and you answered my question on chat. I wish I knew your channel when I had my stock ECU installed with Binary Editor and my quarterhorse. Just subbed to your Channel
Thanks man. What are you tuning with now?
@@LeechMotorsports Holley Terminator X max trying to make a decent timing map
That’s definitely a good one. I’ll cover that very very soon.
@@LeechMotorsports that would be awesome I'm looking forward to the video. Hey I got a question is there a idle timing that you should be shooting close to or is it basically give it what your car likes? I have my idle timming set in spark table @18.1. Yeah I love the Terminator X I was very surprised on how well the car drove with it not being tuned the only thing that I have been having problems with is the idle control valve I have tried using the GM sensor which seemed to be worse so I had to used one of my pwm inputs for the Ford IAC but I don't think it has anything to do with the Holly Terminator I know it's something I must be overlooking but trial and error is how we learn
Email your global file, a log, and basic info about your build to me at matt@leechmotorsports.com and I can take a look.
I bought a 89 GT in February. Drove it 2 hours home. But a new maf and tps and plugs and wires. Runs like crap!
Every time I start the car it runs differently… I pulled the emc out, after checking everything. My car has a A3M computer in it. I’m at a loss and about ready to give up.
Don’t give up on it! What mass air meter and injectors are you working with?
Mine is stock ecu after driving around Mayne 20min in from being cold it jumps to 1800rpm and doesn't come down unless car gets cold or slightly warm while it does that it then doesn't start when hot unless it's too the floor any idea?
Not starting while hot unless pedal to the floor means you either have too much fuel or not enough air during cranking. The high idling could be tons of things. Would have to see a data log to investigate.
Question why would the idle go up when the Tps looses its signal or have a glitch?
It’s because of the “auto resetting” nature of ford efi. Once they is turned on, the ecu keeps a running value of the lowest tps value seen since the key has been on. In a system that is working correctly, no matter what you do with the throttle, it should always return to the same spot. And so that “low value” doesn’t change. But if the sensor has a temporary drop, it will push that closed throttle value lower, then immediately when the signal comes back it will think you are way above closed throttle and thus it leaves idle mode. You get stuck in decel (dashpot mode) so the idle air valve hangs open and the ignition timing stays high and locked.
Thank you for your response, ever since I replaced my TPS with a autozone tps I have be having what I think is tps glitch issues, I just got a motorcraft tps just haven’t install it yet ,1993 Notch back , absolutely love the knowledge I’m learning from you , makes me love my fox more and more, keep giving us Foxbody enthusiasts entertained .
@@LeechMotorsports does Holley do the same? My car will idle on Terminator x and out of no where the rpms will go up. When i look at the screen tps is steadily climbing.
Yes. If the tps goes above 2% in Holley efi, the ecu will believe you are at part throttle. And when that occurs the timing will advance and the idle air valve will open up, which forces your rpms higher and the only way to bring them down is shutting off the car. I have a seen a glitch on a couple Holley cars where the tps signal just climbs the entire time the car is running. No resolution from Holley though.
@@LeechMotorsports i appreciate your response. I read your post about holley being the bane, etc.. so it means alot that you would take the time out to respond.