I need help with a 2nd gen 3.1l in a fiero

[mtownfiero]

I cant seem to get the idle down on this to what it should be even though ive checked the vac lines over and over and even blew smoke into the intake with out any leaks anywhere. It starts up and idles between 1500 and 2000 and throws a code for the tps. What im wondering is if the way i have my vac lines set up would cause any problems. On the tb ports i have the first port from left to right looking from opening side fuel rail, blocked, and MAP sensor. The port on the bottom of the uim is blocked and the one on the backside is hooked up to the brake booster line. Other problems with this are also that when put in drive the rpms drop to around 1k and if you give it gas sometimes it stumbles and if you stay on it, it dies. Its running rich too? Im thinking that it must be a problem with the coils or ingnition system but has anyone else experienced these types of problems? thanks a ton for any help, andrew.

[Joseph Upson]

I cant seem to get the idle down on this to what it should be even though ive checked the vac lines over and over and even blew smoke into the intake with out any leaks anywhere. It starts up and idles between 1500 and 2000 and throws a code for the tps. What im wondering is if the way i have my vac lines set up would cause any problems. On the tb ports i have the first port from left to right looking from opening side fuel rail, blocked, and MAP sensor. The port on the bottom of the uim is blocked and the one on the backside is hooked up to the brake booster line. Other problems with this are also that when put in drive the rpms drop to around 1k and if you give it gas sometimes it stumbles and if you stay on it, it dies. Its running rich too? Im thinking that it must be a problem with the coils or ingnition system but has anyone else experienced these types of problems? thanks a ton for any help, andrew.

Why are you ignoring the TPS code? You can't find a vacuum leak suggesting the TPS is the cause of the high idle problem, if it's bad it could be sending a higher voltage signal to the ecm causing the high idle and in all likelyhood it is the reason the engine is running rich if the above hypothesis is correct since it would be getting a signal for open throttle when the throttle is actually closed. My experience with a bad TPS sensor is that it can make the car near undriveable among other things. I accidently submerged one in water I believe while cleaning the throttlebody and the first sign of trouble in addition to the code was a high idle that if I remember correctly was above 2000 rpm.

[mtownfiero]

I didnt exactly ignore it. I had swapped out the tps with another one i had but i didnt know if either were good. I also changed the 02 and spark plugs and map with no real difference.

[1meanz]

also, maybe check the iac. it sounds like its your tps butttt. if that doesnt fix it then iac would cause high idle also

[Joseph Upson]

I'm guessing you're using the Fiero intake, you need to check your TPS wiring at both ends of the harness since you are getting the code over two different sensors. The IAC will affect the idle, but I'm not sure if it will cause a TPS code to be set although it sounds feasible in the event of a higher idle than what the TPS value should be supporting. Close of the the IAC port inside the TB and if that stalls the engine you can be pretty sure there's likely no intake leak.

[mtownfiero]

Im actually using the stock 3.1l aluminum heads and intake not the fiero ones. put a new tps in today and still got the same and more problems. After installing the tps it ran slightly better and idled at 1500 but still threw code 22 and 34. 22 i believe is still the tps code. So i tried unplugging the battery to restet the ecm and the idle would just get higher around 2-3k. When you try to put it in drive some times it wants to go like a bat outa hell other times the second you put it in drive it dies? Seems really strange to me.

[carbon]

That just screams lean high idle due to vacuum leak. High idle but dies when put in gear. A good test is to start it up in the dark and watch for the manifolds to start glowing.

[mtownfiero]

i did a smoke test for vaccum and it checked out fine. The manifolds are getting hot very quickly though.

[carbon]

Possible IAC problem? Dirty IAC passage or pintle not moving? Would have the same symptoms as a vacuum leak...

[mtownfiero]

tried pulling the pintle out of the iac and replacing it unplugged so the passaged was blocked and the car ran a lot better, still idled a little high but much better than before. I bought a new iac and installed it today and its running better still but im having problems getting it to idle and i still have an rpm drop and occasional power loss in gear. I read somewhere though that you have to drive over 40 or something to get the iac to reset the idle? Is that true.

[55trucker]

Andy.....are you still having troubles with this setup?........thought you cured all of this headache last November..Code 34 should be the MAP Sensor, Code 22 is the TPS ...with that 3.1 engine ..what ECM are you using?...a manual or an auto ECM out of the Cav?....reason I ask is....are you setting a high idle code at all now that you've changed the IAC?....if there is no code set then the ECM thinks there is nothing wrong with the engines rpm out of gear...why is that?...if it's an auto trans ECM then the ECM will be looking for a signal off the neutral safety switch to let the ECM know the car is not in gear and to engage the idle circuit. The manual trans ECM takes its info off the speed sensor.

Steve

[mtownfiero]

No i never fully cured all the hiccups with the car. I am using the 7730 ecm with the aluminum heads and the 3spd fiero auto. I had my chip reprogrammed by Darth from pff to be set for an auto trans. Is it possible there is something wrong with my trans. For some reason i think i remember that when the 2.8l was in there although it was knocking that it dropped the rpms in gear as well.