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Intermittent stumble + limp mode, bad times


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Its an 05 lgt 5eat, bone stock minus the washer mod on the exhaust. We have had issues with the TPS before, sudden throttle input makes the car go into limp, get cel and cruise lights, but turning the car off and back on after a few minutes has always "fixed" the issue. Why haven't we replaced the tps yet? Well, we are lazy and until recently broke. Anyhow, that happened today on the highway after turning off cc. Heres where it gets fucky.

 

I pulled over, it was in limp mode so that's all I could do. Shut off the car, hung out in the rain for a few, turned it back on. Idle was good, revved fine. So, i throw it in drive, and slowly accelerate back onto the highway. Went great for about 10 seconds, when it started acting like it was pulling timing, or going in and out of limp mode seemingly randomly. I dont need to tell you how much the car lurched every time it decided to accept my throttle input. This was new, so I pulled over again. Turned off the car and waited another 10 min or so. Turn it back on, same deal. I can cruise it about 25-30 with light throttle input, but I definitely feel it going on/off with power.

 

I limped it off the highway slowly, got into a parking lot and checked intake hoses, tmic (I've read it can separate at the tanks), even got down under the dash and unplugged/cleaned/replugged the TPS. I turned the car back on and.... no CEL, no cruise light, car accelerates and drives like normal. Wtf. Does this just sound like a seriously failing TPS or could it be something more serious? Cant find my code reader but will get them read asap.

 

Apparently the car is a out 2k mi past the tire rotation, could uneven wear contribute to this? Probably not because that would be drivetrain related but you never know with all these fancy computers and such. Thanks for your time!

 

P.s. I've searched for this specific problem and came up empty, so apologies if this has already been asked/answered.

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I had TPS issues in the past before. Scary moment when on the highway in the left lane going 80mph and suddenly losing all throttle response.

 

Try unbolting the gas pedal assembly and taking apart the TPS. Clean it with electric parts cleaner and lather a generous amount of dielectric grease on it. Worked well for me. The lurching could definitely be from the TPS being funky.

 

As far as I know, you cannot go in and out of limp mode so it’s plausible that this is all due to the throttle. If you are in limp mode, the revs will not go above 3.5k RPM, even in neutral.

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Okay cool, I wasnt sure that was worth it but I'll give it a go. Thanks for the suggestion! I'll be sure to update when its fixed/replaced.

 

Also still haven't found my damn code scanner. Dunno what happened when I moved but it is nowhere

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Other things to look at are the OCVS getting and O2 sensor getting old. Codes will help isolate the issue.

Worst issue I had was a stuck open waste gate that I had an independent shop diagnose and repair, dealer was no help, have a spare stock two port waste gate solenoid because of them.

This was the beginning of me getting my head around this car and doing the maintenance/repairs myself.

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