Ive been having what seems like TPS issues since I swapped the engine in my GST. For the most part the car drives fine. But when I let off the gas say at 2500rpms...the AFR will drop to ~12:1. Before the car would jump to ~17:1 and then read LEAN on decel.

I wouldnt really care but its screwing with my fuel trims real bad. When Im slowing down with the car in gear, since its running at 12:1 it tries to lean itself out. So when I take it out of gear and it starts to idle the AFR is really lean (16-18:1) from the ecu pulling fuel. It will do the same thing when switching gears depending on how fast I shift. Ex: when I shift from 4th to 5th just cruising, it goes 12:1 when I let off the throttle and then right when I get back on it it runs at 15.5ish for a second before it richens back up causing a hesitation.

Another thing to note is that when I decelerate from about 4-4.5k rpms, it will do its thing like normal, and then right around 2200-2000rshared_pm it will jerk and go all the way LEAN like it shutting the injectors off like its supposed to. But as soon as I see the gauge jump lean it starts jerking and then runs rich again.

Ive tested the TPS every way I could find and it seems ok. Resistance is in spec. I pulled the throttlebody and set the TPS with a feeler gauge (.45mm) twice to no effect. When the throttle is closed the idle switch circuit is closed. As soon as I put the feeler gauge in it opens. It takes about a 50mV rise to open the switch. I probed the harness while its powered, and the TPS reads 4.96V when opened all the way.

Is there anything else I can try or should I just bite the bullet and replace the TPS to see if it helps? Also, is there a pin at the ECU I can check to see if the idle switch circuit is in good shape?

THanks!!

 

41 views and no one has any idea? does that mean Ive pretty much covered all the bases or what? lol

 

i know that your car is having symptoms so i doubt it's this, but have you tested the wideband sensor? thats very easy to find out if maybe it's also adding to the issue.

 

I do think my wideband may be reading incorrectly. I have tested it all the ways Ive found.

I got a proposition for ya tho...lol...anything I can offer (cash/help on the car etc) to persuade you to let me test out your wideband on my car? Cause Ive been dealing with a "lean condition" thats unrelated to this issue for over a year now. Ive done everything I can think of to fix it. I was about to buy a new Innovate wideband but its kinda hard to spend $180 replacing something you dont even know is broken lol.

 

ya man. catch is that you have to come to my house. my wideband has 5 miles on it tops and reads perfect. no problem you putting it in your car for a bit. i'm not using it, i need a tranny

 

Main problem, its a DSM. lol. Kidding, love the cars! I would guess the wideband as well might be throwing some odds numbers on you.

 

have you tested it with a gas-soaked rag yet dude? and see if it's reading full rich?. could also be an exhaust leak as well that is located before the sensor (that was my problem)

 

u need a tranny now to?????im gonna start a psycho fund hehe

 

Does that actually work? You just pour gas on a rag and wrap the sensor in it? Couldnt that catch fire? lol

Its not an exhaust leak. I do have one right now b/c I messed up a gasket or something a couple days ago but it ran lean at WOT long before that. And the leak didnt even affect my readings anyway.

 

is the leak before the sensor? if an exhaust leak before your sensor didn't change your reading even a little bit then i would go ahead and say your sensor is bad. it should have changed a little bit.

but yes, pull your sensor out and just set it on the ground or your fender or somthing and turn your car on. make sure it goes to full lean, and then put a little bit of gas on a rag or paper towel (don't go crazy with the gas lol). then set the sensor in the rag and check the readings. if it doesn't go and stay at full rich i would go ahead and say the sensor is bad.