I have a terrible idle. When it is cold it is steady, but high(1200). When it is warm it's low(500), rough and stalls out. I checked everywhere for vacuum leaks, but haven't found any. I decided to disconnect the electrical connector on my MAP and it smoothed out. Doesn't run perfect, but alot better. What does this mean?
It hasn't been throwing any codes. It's got a cc quadrajet.

 

anyone?

 

Your idle speed problems are very likely due to the carb. The idle speed issues should be relatively easy to change by throttle stop screw adjustment. The shop manual should give you some good pointers to what adjustments are available and necessary. If you haven't already, you'll want to modify the base to get access to the idle mixture adjustment screws so you can tune it appropriately. There's a good book on Rochester carbs by Doug Roe that might help you, too.

Next, check the base timing. I'm not completely familiar with the inner workings of the CCC systems. However, I would imagine all that changed (at idle) when you disconnected the MAP sensor was a timing change. The behavior should have been similar to what would happen if you disconnected the vacuum advance from a non-CCC distributor at idle. As you mentioned, it probably didn't really "help" the problem. Just masked it a little....

Finally, take a good look at the EGR valve. It's not unusual for these to get debris jamming the pintle such that there's always some exhaust gasses going into the cylinders. Check to make sure the EGR valve itself isn't getting any vacuum at idle.

Good luck!!

 

Thanks for the info. Looks like I need to check the timing. The EGR vacuum is capped off, so I don't think that would be the problem. Would the timing cause bucking under wide open throttle or does that sound more like lean secondaries?

 

You'll still want to pull of the EGR valve to make sure it's not gummed up. If it checks out, you're good to go (regarding idle problems) since it's capped off.

Carb secondaries are a possible source of the "bucking". If the problem is running lean, you'll also want to make sure you have sufficient fuel flow/pressure at all operating conditions. There might be enough to keep things in order at lower speeds. But, at higher speeds, it's going out faster than coming in! Plugged/clogged fuel filters can cause this type of problem.

You'll also want to make sure the ignition system (cap, rotor, wires, plugs) are all in good shape. I've had plugs that seemed to work OK at idle screw up at higher RPM.

In short, make sure the basics of fuel and ignition are covered before tearing into the more complicated stuff!