Linguo415

iTrader: (1)

I just got a 90 fc GLX. Its great. I noticed that at night after a short drive the Idle kinda starts bogging out. It drops almost to the point of shut off then shoots back up then back down until I shut the lights off and then it stablises again. Ofcourse its only noticable while I am stopped. I thought it may be a bad bac. The ac dosent seem to affect the idle much. Also sometimes when I cold start it the rpm dose not go to 3000. Any insite on the funny idle?

Aaron Cake

iTrader: (1)

Almost all idle problems are caused by:

-vacuum leaks
-TPS misadjustment
-sticky/clogged/unplugged BAC valve

In that order.

Linguo415

iTrader: (1)

I thought it might be a vacuum leak. Ill have to take some time and check. I dont know where al the vacuum hoses are. Is tps Throttle position sensor?

Aaron Cake

iTrader: (1)

Yes.

You will find the Factory Service Manual in the FAQ, which will answer most of your questions.