First off, it's an '87 Formula 305 4bbl LG4 motor. The problem is at startup wont hold an idle sometimes, I have to hold the rpm's, then when it warms up it seems to be ok ,but not always. It only seems to happen when it's either raining outside, or there's alot of moisture in the air. I replaced the air temp sensor in the air cleaner, but nothing changed I also changed the cap/rotor/wires, and still nothing changed, it still had issues today in the rain. Could it possibly be a choke problem, or thr air cleaner vacuum motor? Any help I greatly appreciate guys:hail: :hail:

 

I have the same problem, my car sometimes won't idle in the rain. Its completely rebulit, carb, engine, ignition etc. I have tuned it on a 4 gas analyzer and a snap on scanner. I also have a dieseling problem i can't nail down. It happens occasionally and it seems to go away for a while when i make a change. If anybody has some experience with this, i would love to hear an explanation

 

Thank goodness I'm not the only one...I thought I was going nuts

 

Me too, hopefully somebody has a fix.

 

:hail: Help...anyone?:hail:

 

TTT?

 

usually problems that happen during rain or high humidity have to do with the distributor cap.

 

not in this case.

 

deiseling can easily be a vacuum leak.
a vacuum leak could be causing both problems.

also, why are you sure that your distributor cap can't have a problem? is it just because it's new?

just curious.

 

the whole ignition is new, it was a problem before i rebuilt it too. When the engine dies, the rpm just steadily drops. There is no "cut off". It runs smoothly, without a miss. i don't think i have a vacume leak for the same reason, my engine runs smoothly. I will take a better look but i have been in and out om my motor many time without seeing any sign of aleak

 

New ignition including magnetic pickup,and controll module?
Is the rubber gromet in place where the wires come out of the dist ? (allows moisture into dist.)
I also suspected the throtle position sensor in my case.

 

accel modual and coil, GM pickup, Gm gear, accell cap and rotor. Grommet is in place, i changed the TPS and the MX solonoid.

 

Well I had the same wet weather stuff and solved it with a non-CC carb and dist. so I suspect old harness wires or conections to the computer. This may not be what you wanted to hear!