so coming home from the track my car starts acting up.



at part throttle, like keeping pace at highway speed, it just stumbles a lot, all jerky and bleh.

so i get home, adjust the tps, it was .6 at idle instead of 1.

okay that should fix it, right? wrong. still stumbles, if anything worse.



stumbling goes away when im engine braking or giving it more then part throttle.



what could be causing this?

j9 thought it could be the afm, so i replaced it.

nope still there.



gonna buy a fuel filter tomorrow and see if that fixes it. its kinda acting like my other na did when it was clogged.

How's the idle? Does the car have an O2 sensor? EGR?

idles randomly.

bounces 1200-1700ish randomly, if i drive it enough it sometimes levels out at either 1000 or 1500. it does its own thing.



02 sensor and egr are there, and should be working. all emissions are there.

It could be a bad TPS. Try to pullssome codes out when is acting badly.

it does it when im driving at part throttle, no other time...



i replaced the tps like 2 days ago. cause the one on it was all rusty and ****.

Hmmm. I'd try the TPS.



Was it acting up before you changed it?



Do you still have the rusty one? Put it back!

Vacuum leak?

starting to think that, it idles wherever it wants to.



althought seems to steady out after drivin it for a looong time. but then itll act up again.



****.



i hate vacuum leaks.



i still hvae the walbro in from when it was boosted.

although after i put it back to na, i never heard the pump whine until the end of practice before the stumbling started. and when it was turbo it always was loud...

maybe its just too rich. it seemed to be missing a little up top randomly.

swapped out the walbro for a stock na pump and changed the plugs.



**** got worse, part throttle was basically just cutting out completely.



changed the fuel filter, thought is was fixed. after a few minutes driving it came back though.

it seems like it only does it after its warmed up for a few minutes...

although the fuel filter was leaking a little bit which may be causing it but **** that ill get a real clamp on there tomorrow.



maybe the tps has a dead spot? i had my multimeter on it and moved the throttle and didnt see one, but maybe its hiding in the baaaarely open position.