williillii
15+ Year Contributor
- 171
- 1
- Jan 31, 2008
-
Tampa,
Florida
So about two months ago I destroyed the motor in my GST.. I put in another one and ever since Ive been having what seems like TPS issues. 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 2200-2000rpm 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!!
TLDR:
car runs rich on decel, then lean when comes to idle.
seems like fuel injectors arent shutting off
tps adjusted correctly, tests fine.
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 2200-2000rpm 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!!
TLDR:
car runs rich on decel, then lean when comes to idle.
seems like fuel injectors arent shutting off
tps adjusted correctly, tests fine.
That would be the first thing to check. If you would have your car in your profile we would be able to tell you what pin to look for or even give a link to a manual for the pin outs.
