Hi, does the mixture control unit have any effect on the motor when it is cold, at start up. My car was running great warmed up, at warmup it was a bit rough. Well about two weeks ago, I started the car up and it was backfiring. As soon as the car warmed up, no problems, great idle, no backfiring. So I went and tried lowering the mixture on the mixture control unit. While doing that I fooled with the idle screw also. Now the car will not idle at all and is running very rich. I never actually get the car warmed up because it dies. I can keep my foot on the gas to keep the engine running but I am vary of if I am ruining something so I do not. If I keep the RPM's up at 2000 it runs smooth. If I keep it around 900, the car backfires from muffler and from airbox. One is saying rich, the other lean. Any ideas. Also, with the idle adjusting screw, how does it work. I know that as you turn it counterclockwise the car should idle higher. Is that because the engine is getting more air or gas and at what point does the screw not have any effect. I turn the screw until the screw almost comes out, and still no idle. Any ideas, thanks in advance.

 

David the adjustments on the CIS are very particular, a 1/4 turn is A LOT! I am assuming that you have taken it WAY out of operating range that is why it won't hold an idle.

Good luck and keep us posted

Sorry that I can't really help

Shawn