Hello again guys,

I've always had a bit of a rough idle when I start my car in the morning. Not bad, but a small nuisance nonetheless.

I took off my throttle bottle and cleaned it. Cleaned the plates and surrounded areas. It was covered in black stuff and looks a lot better now.

That took care of the majority of my rough idle. RPM's no longer jump. I'm wondering about a different type of rough idle.

In the mornings if I get on it a little bit (not hard driving, just goosing it a little), then let's say I stop at a stoplight.. it'll idle very rough. The RPM's don't jump at all.. it stays around 750-800. One time it even died.

This is all when the coolant temperature is reporting about 115 or so. If I let the car get up to 160-180 or so (which I always do before really "getting on it") then there's no such problem after I give it a little gas. Very smooth, pleasant idle.

I'm wondering if this problem may have something to do with my absolutely trashed precats clogging up my exhaust, and maybe the problem doesn't come about when it's warm. If that's the case, I'll know next week since it's first on my priority list.

I don't think it'd be leaky injectors, because they were repaired only a few months ago. Even so, I'm not going to rule out the possibility.

Also I suppose it could be a vacuum leak.. but I have no experience with vacuum leaks, and I always heard that I'd have a variable RPM idle if that was the problem.

Anyway, thanks for hearing me out. Any pointers would be appreciated.

 

O2 sensor maybe, did you take apart the IAC when you took off the TB?

 

I didn't. I wanted to familiarize myself with the area (and make sure I could get it all back together) before I did that. I did find a great guide to it online, so I'll probably go back and do a little more thorough of a job now that I feel comfortable with what I'm doing.

As far as the oxygen sensor.. I wouldn't doubt that's the problem. And again, if that's the problem then it'll be fine soon. I had planned on replacing O2 sensors next week.

Thanks much.

 

the IAC gets pretty gunked up. the car smooths out when it goes "closed loop" after the 02 sensor reaches operating temp so I wouldn't replace them just yet.

first try taking the IAC apart, clean the tip, and the "seat" where the tip goes and see if it doesn't help.

the injectors maybe getting pretty dirty too and so when you start up in running off the chip

 

Thanks for the reply. I'll definitely give the IAC a cleaning, just for good measure.

I was under the impression that IAC only controlled the idle RPM though. I'm learning what all this electronic stuff is (I'm used to older 350's), and hopefully after reading my manuals all the way through a time or two again I'll have a clearer understanding of how it all works together.

Anyway, the rough idle is pretty bad.. the whole car feels like it's shaking from where I'm sitting in the driver's seat. But my RPM's aren't fluctuating. Staying at a steady 750 or so. Could this still be IAC?

I'm still going to replace the O2 sensor, just for good measure. I know nothing has been done in this area in a long time, if ever. And I'm at 104k miles. Plus I've noticed that I've dropped 1 or 2 mpg anyway. I'll be glad to get rid of my "self-gutting" cats.


[Modified by Tourney3p0, 3:17 PM 10/8/2002]