MikeinBloomfield

Hi Guys--
The 1982 AT car I bought in Denver arrived Monday night, and I'm thrilled. Beautiful car, it looks like its never even been driven. Pics to come when I get a chance to hose it down and I get to drive it in sunlight.

I've taken it on two half-hour rides, never really pushing it. However, I've noticed that when I first start it, it idles very rough, almost stalling, but not quite. After a minute or two, it settles in and idles ok at about 300. The tach needle doesn't move, but there still is a noticeable vibration. It doesn't seem to affect power or acceleration.

Any thoughts? I have no idea how often this car was driven recently. With 67,000 miles on an 82, it obviously wasn't driven very much at all so far. My point is, it feels like something that might take care of itself after some use. When ThomO drove it in Denver, he didn't mention a rough idle, so I'm assuming it's a recent issue. And also, this car spent most of its life at a very different altitude than NJ, could it be adjusting to that? I bought some injector cleaner, but I wanted to ask the question here first before I use it.

WallyP

300 is much too low. Check the idle speed with an accurate tach, and adjust as necessary.

MikeinBloomfield

WallyP, thanks! Makes sense. From searching the forum, I see now it should be idling in the 650 - 700 RPM range. If this solves the vibration problem, I'll be very happy as its the only (minor) thing bothering me about the car.

What do you think would cause it to idle so low, if the tach is accurate? Would these be correct settings for a high-altitude car?

WallyP

No idea why it is idling so low. You might try just speeding it up close to spec. Look down by the oil filler and find the large slotted screw head. With the engine warm, use it to adjust the idle speed.

James Bailey

The early injection is none adaptive for the most part....it does use the O2 sensor to trim the mixture. But it really does not learn very much ! You must set the idle and adjust the timing.

MikeinBloomfield

Hi again
My mistake. Fully warm, its idling just below the line under the "1" which is where I believe it should be. Still running a little rough. What's my first check, the timing? Is a timing light the best way to do this? Can I just check the timing marks?

It's not so severe that it would keep me from driving it, but I want to make sure it doesn't become a bigger isssue.

Thanks!

James Bailey

OK new car to you you can not assume anything. It could easily be a vacuum/intake leak causing a lean misfire at idle but also many other possibilities. Due to the cost many items which would have been changed on a Chevy get neglected.....plug wires, caps rotors, oxygen sensor etc.

MikeinBloomfield

Thanks James, where would you start? Just had the hood open while running a little while ago, and no fireflies.

James Bailey

Would be good to pull the spark plugs see what they look like. While out do a compression test. Plugs are cheap so put in new ones. Inspect the cap and rotor. Look over all the vacuum lines as well as anything else rubber under the hood, much of it will be toast. Check the injector connectors they break easily. Timing you check with a light. If you have someone sniff the exhaust it might give you some idea what is going on.

MikeinBloomfield

Thanks James, I'll start with the relatively easy stuff you've outlined here. Again, it FEELS like a minor issue. The tach needle doesn't even move, although the oil pressure gauge bounces around a little bit. Here's hoping that's the case.