How is this possible??? With the car off my new TB acts perfectly. You blip the gas from under the hood or with the pedal and it always returns back to 0% and rests on the stop screw. With the engine running you blip the gas and it does not close all the way. It will close but there will be a small 1 mm gap between the linkage on the TB and the stop screw. The only difference with the car on is air is moving through the TB. TPS is perfect, I lubed the hindes, I even wound the spring around one more time so it force it back harder. Anybody know whats wrong???

 

TTT, come on people, you ask what catback sounds the best and you get a zillion responses and when you ask a semi technical question you get none??? I need to figure out what the hell is wrong with this? How can something be fine with the engine off and then start acting up when it is running? And I'm sure the airflow is not strong enough to push the throttle open... what could be happening??

 

I would think it would need to stay a little open while the motor is running If it were closed how would you have an air/fuel mixture at idle??

 

Thats what the IAC does, it electronically controls the idle by allowing more air in the intake Via the passage on the bottom of the TB.

I would bet on the TPS. Try starting the car, watching the volts, the turning the car off too see if it drops. Without disconnecting anything. Just watch from Engine on until you shut if off and see if it changes w/o breaking the connection.
IF the spring is weak, it's very possible that the throttle could be slightly open. Try taking your hand and trying to close the throttle more while the car is running to find out if it will actually close more

-Shannon

 

I know you are frustrated, but realize that there are going to be few people that have come across this kind of problem.
Tick everyone off with an attitude and you will probably get no help.

 

Well this is the third or fourth post I made on the subject and it is quite frustrating. And honestly, what I said is the truth and I'm sure you know that. I'm sorry if it was offensive.

Shannon- The throttle does not close all the way (physically). The TPS works fine I'm sure of it... I've tried everything but there is something that only happens with the car on and makes the throttle not go back all the way. Like usually the lever on the side where it connects to the throttle cable touches the screw. With the car off it touches the screw. But with the engine running and your foot off the gas, it's like 1 mm away from the screw but it's enough to cause an erratic, high idle.

 

Kind of disappointing that you feel the amount of help you got so far was "none". Several of us have tried to help... and its not easy to fix someone else's car on the first try, over the Internet. He!!, the dealer can look at it for a week, charge you a couple hundred $$$, and give you no better an answer than you got here .

Did you measure the TPS voltage as I suggested? I really think if you get the TPS set at the correct voltage, the one millimeter of blade movement will not be an issue.

Did you check to see if you have a broken motor mount and the engine was torquing excessively to one side when it is running, stretching the throttle cable.... may sound silly, but it has happened.

 

not trying to steal the post but sense were on the subject, how do you reset the iac

 

Yeah, I know it is the truth. It's because everyone has a cat back, but not everyone has a 52 or 58mm throttle body. (I hate the cat back posts, myself).

Try removing the cruise cable if it is on there. Maybe it is holding it open. Heck, even remove the accelerator cable and then play with the TB. That will eliminate a couple of things. I am assuming you don't have ASR.


97Z-M6:
Try this for resetting the IAC:

-Depress accelerator slightly

-Start engine, then release accelerator pedal, run engine for 5 seconds

-Turn ignition "OFF" for ten seconds

-Restart engine and check for proper idle operation

 

I'm with Fred on this one. Check the TPS voltage and see if it is in the needed tolerances. I had similar problems just a few weeks ago. Fixed the TPS voltage and everything else fell into place. As for the IAC, you can always add more air by doing the little air mod with a hose off of the intake. That worked REAL good. I did it too.

Q

 

Thanks for all the replies. Freescan reads TPS voltage right? I'm going to pick up the laptop to day from my friend's house and scan this sucker and see if the TPS is getting the correct voltage. There is a tolerance for it right? Hopefully that little 1 mm gap won't have an effect.

 

You can download TTS Datamaster too. It will let you do 20 logs free.

 

TTT