Idle issue after plenum/tb install

[86saleen]

I installed a Accufab/C&L plenum on my 02GT 5spd and now have a high idle issue. What should I look at as a cause? When I first started it, the car idled at 1100rpm then would drop to 800rpm after a few seconds. It did this repeatedly for 15min. even after revving the engine. However, while road testing the car it picked up a constant 2500rpm idle. Any suggestions? Thanks.

:SNSign:

 

[Cobra123089]

Did you disconnect the battery when you did the install?

 

[86saleen]

No, I didn't. Should I?

 

[Cobra123089]

Ya do it for a good 15 mins, then start it and let it idle to operating temp. This is what i did when i installed mine.

 

[86saleen]

I'll try it. Thanks.

 

[Cobra123089]

Let me know if it works.

 

[SaleenGT2001]

it is prob not sealed somewhere. check all the gaskets. mine had a leak around the egr. it caused it to idle very high b/c it was sucking in extra air.

 

[SaleenGT2001]

there is no electronics that control idle. it all either cable operated or vacume operated

 

[lexluthr69]

The Idle Air Control valve is absolutely electronically controlled, and it is definitely a good idea to disconnect the battery to clear the learning the computer has accomplished with the old plenum and TB on. The computer will now begin to adapt for the new TB/plenum.

If that doesn't fix it, begin looking for vacuum leaks around the EGR port (as previously mentioned), the IAC port, as well as where the TB meets the plenum. Obviously any hoses should be checked to ensure tight fitting.

 

[Dragstr05]

I'd be checking for vacuum leaks and TPS voltage.

 

[steveb24]

there is no electronics that control idle. it all either cable operated or vacume operated

thats a bunch of crap

 

[SaleenGT2001]

thats a bunch of crap

nice way to correct me sorry i forgot something. as i said earlier check for any leaks.


and reset your battery!

 

[86saleen]

Started it after it cooled. Idle is back at 1000rpm. The battery is disconnected to reset the computer.

 

[timk]

i don't know about your specific throttle body, but most aftermarket tb's DO NOT have the small hole drilled in the throttle blade like the stock tb's do.

it may seem small, but after doing 3-4 of these myself, i found that idle quality improves significantly when i drill the hole.

food for thought. there should be no other reason for poor idle quality if there are no vacuum leaks.

 

[Jsun3701]

Dude check your vaccumm hoses, its very easy to mix them up.

 

[Jsun3701]

Check this thread for a pic of the hoses to check.http://forums.stangnet.com/showthread.php?t=675490
Hope this helps.

 

[sgarlic]

Give it a week and I bet it fixes itself.

I asked the exact same question when I did my Accufab Plenum/TB.. and got that answer (give it a week) and sure enough, a few days later it was gone. I read somewhere else that driving with the A/C on helps it learn idle more quickly.. but I didn't.

Disconnecting the battery will totally reset what the PCM has learned about controlling the idle, so it'll probably just take LONGER to relearn the idle that way.

 

[86saleen]

Reconnected the battery and the problem still exists. 1000rpm idle upon startup and 2500rpm hanging idle while driving. Shut the car off and 1000rpm idle returns. It also seems to take a while for rpms to drop when revving the engine. I had 800rpm idle before and no hesitation for idle to return after rev. Any thoughts? Don't seem to have sticking throttle and don't have visible vacuum leak. How do I check for leaks? Thanks.

 

[lexluthr69]

Have you tried adjusting the throttle set screw? If you don't have any vacuum leaks, than the only other thing I can think of is that the throttle plate is stuck open wider than it should be. Are you certain you don't have a vacuum leak somewhere, or possibly a hose disconnected?

 

[COramprat]

Probably the throttle position sensor. Make sure it is installed correctly so the the TB blade activates the pins inside the sensor. You may have to slide it on at about 90 degrees and rotate it into correct position.

It is not recommended to adjust the throttle set screw. Try my suggestion and see if it helps...I had the same problem and this fixed it.