rough idle runs rich then smooths out
 

i have a 89 camaro with a l98 and its always idled high since i bought it when i first start it. Now for the past month or so once in a while when i start it it will idle like it has a thumpr cam in it and run rich. Then the ses light comes on and itl smooth out and itl be fine. The next thing is when its in od and i coast the rpms drop and its like the motor falls on its face when coasting. Then i tap the gas and it picks back up. I put new plugs in her and that fixed other problems but the rough idle is the next one. also it gets about 12 mpg, which i think is the O2 sensor. any help is appreciated thanks

Re: rough idle runs rich then smooths out
 

You need to check for codes since the SES light came on. That will get you started so you know what to start chasing for. Probably not the o2 sensor but you can try a new one since they're fairly cheap. With a high idle at start up, my guess would be bad intake gaskets. Start with checking the codes.

Re: rough idle runs rich then smooths out
 

Well now she starts normally and then it'll start surging and wanna die then idle high then the ses light comes on and it runs fine after that. I tried scanning it and it wouldn't pick it up but when the ses flashed it was one long one then one shorter one then one long one again. I tried looking for it on here but didn't see anything that would help. Here's a video of her running like a pos. sounds like it has a cam in her! Hopefully this helps

Re: rough idle runs rich then smooths out
 

Maybe it's the maf acting up?? Or vacuum leaks??

Re: rough idle runs rich then smooths out
 

any ideas?? its my daily driver and its starting to get old haha. thanks!

Re: rough idle runs rich then smooths out
 

I have an '85 Trans Am with 305 TPI which is doing the exact same thing.So far I haven't found the problem.

Re: rough idle runs rich then smooths out
 

its odd...then itll idle fine and run fine

Re: rough idle runs rich then smooths out
 

now she wont stay idling when i start it sometimes

Re: rough idle runs rich then smooths out
 

I had a very similar problem, ran rough, exhaust burned my eyes and nose. died at idle.. turned out to be the MAF

Re: rough idle runs rich then smooths out
 

Posted to wrong post