Okay then. I've been having idle issues with my formula for quite some time now. It's a 350 TPI 1987 firebird formula.

Basically there's several things going on here. Initially, it was simply what appeared to be a sticking throttle body, which I kind of ignored for the time being. However, lately the engine feels like it's running rougher and rougher. At an idle, when the throttle doesn't appear to be sticking somewhere over 1,000RPM, the idle will go back and forth from 400RPM to 800 RPM. Sometimes it will seem to wave back and forth slowly, other times it seems to almost be heaving up to 800 RPM and immediately back to 400, then heave again, in rapid succession. It's intermittent, so it's really hard for me to figure out what's going on.

When it's sort-of behaving I'll watch it go back and forth slowly from 600 to 400, back up to almost 500, then it'll drop to 300, and stall.

Additional notes:
If I turn on the car, it'll idle around 1,200 RPM and slowly work it's way down over the course of a minute or two. If I leave the car sit for about 10 minutes and drop it into gear, it'll immediately stall. (Almost always.)

My Service Engine Soon light is NOT on, but as a test I disconnected the MAF Sensor and started the car. It idled at 1,200 consistantly, but at that idle, it's almost like having your foot on the gas pedal the whole time. At that RPM I thought the throttle was stuck forward again, so I went to push it closed and it stayed at 1,200.

Any ideas?

 

'xar

There are couple possibilities:

1) Take out IAC and clean it and reset it. There is a sticky (use search) how to do so. MAF cars can have finicky idle issues and dirty or malfunctioning IAC can aggravate it even further.


2) MAF sensor, more than likely, is dirty. There is a sticky (use search) how to clean your MAF sensor. MAF sensors do go bad over time due to wire contamination. If you clean MAF sensor and there is no measurable improvement you are looking into a MAF replacement. With MAF disconnected ECM goes into default mode - 1200RPM.

As always check for usual problems - vacuum leaks, stuck EGR, etc

//RF

 

After mucking around a bit I noticed a faint hissing sound, so I looked around. Looks like it's vacuum related after all:

http://a128.ac-images.myspacecdn.com...3da14040df.jpg

The one on the right is what was on. It was a T, but apparently it broke off. I put the new one on and the car doesn't stall as easily now (it still does), and the idle is a little more controlled (still not perfect). And yes, there's still a SLIGHT hiss sound, so I assume there's another vacuum leak someplace. The vacuum hoses right now are the stock ones from 1987, so I'm thinking a complete vacuum hose overhaul may be in order in the near future.

Also: the throttle still sticks

 

Found my vacuum leak. Wasn't where I thought it was.

Aparently my big leak is on the hose that connects to the PVC valve. (I think that's what it's called...) I replaced a bunch of other vacuum hoses because they were just old as **** (stock hoses from 1987.) Then I found this one, I don't have this size hose available at my home, so I'll have to stop down advanced auto parts after I get off work. Unfortunately, it'll be dark then. Guess this one will have to wait till tomorrow.

http://a194.ac-images.myspacecdn.com...0de671e3d9.jpg