I'm hoping someone can help me diagnose a recent problem with my LG4. When starting the engine cold, the idle is extremely rough (shakes the whole car) and the engine will stall if I do not give enough throttle to keep the rpms up. After one or two minutes, the idle smooths out completely, though the rpms stay at around 1100 while in park. When I shift to drive or reverse, they drop to a more normal 500-700. The car drives fine. When the engine is warm, the startup is normal. I do not drive the car daily, and it has only started this problem recently. Does this sound fuel related, vacuum related, or am I totally off the mark.

Thanks for any input.

 

check your IAC, also check and see if your AIR pump can turn freely by hand.

Your idle speed looks right. Thats what mine was at.

 

Sounds like the choke isn't setting correctly. Pull the air cleaner and check the choke linkages for sticking, plates for gunkiness, etc.

 

I agree with this. The rest looks on par with what a quadrajet-equipped vehicle should be doing, the initial high idle, dropping when in gear, all that good stuff.

A can of WD-40 helps out.

 

Thanks for the replies - I'll check it out tonight.

 

Check the choke pull-off which is mounted on the passenger side of the carb. with a small vacuum hose hooking into it. It's designed to open the choke plate a certain amount after the engine is started up cold. It's vacuum operated and if the diaphram is blown inside it won't operate and can cause the rough running when cold as you described until choke opens later during warm-up. They are available at most part stores.