Idle problem - CIS system on 77 3.0

Argeo · 06-02-2003, 10:38 AM

Hi, the engine idles fine. When I bring the RPM's up to 2000 or more and then let off the accelerator the rpm's drop quickly to 3 or 400 and then dies. Any one know what this may be a symtom for? Too lean, to rich? Also, when the car idles every 20 secs or so the engine will like slow down and then speed back up to idle of 900. All within a second or two.

Last, since my two great sources of info have conflicting stories of when a engine is running lean or rich, maybe some of you can settle the debate. When a car backfires out of the pipe, is it rich or lean? What does a backfire out of the airbox mean? Does a bouncing RPM guage at idle mean running to rich?

Thanks in advance.

Groesbeck Hurricane · 06-02-2003, 12:28 PM

Argeo,

Is the motor warm or cold when you have the problem? There are some other reasons besides lean or rich fuel mixtures. When you say the engine idles fine, what is the RPM. Is this only at start-up when cold? And if you have not already installed the backfire valve in your airbox I would highly suggest you order one from Pelican today. Order a copy of the 101 projects at the same time. Thanks,

Argeo · 06-02-2003, 12:36 PM

Got the valve, got the book. Thanks. it had been running for a few minutes. It was no way at operating temp of 80C. It used to work fine. I tinkered with the AAV, WUR and the plate adjusting screw and now it starts alot better but now I have this problem.

Thanks, do you know the answer to the backfiring piece of the question.

Thanks .

Argeo · 06-05-2003, 05:02 AM

I may be all set. I decided to hold off adjusting the WOR until the car got warm. Before starting, I did richen the system using the adjusting screw (cw)on the sensor plate. Well I started and it ran a bit rich so I backed off a hair on the sensor plate (CCW). It then started really well. Well, as it warmed the car seemed to be running a bit lean so I fine tuned with the throttle body adjustment (CW). I had to move a hair at a time but the engine eventually idled really well and would go back to idle after a hard acceleration and sudden deceleration at about 60C (wouldn't do before). Anyways, it ran well last night (still not road tested) but I guess I will not know for sure until I test again.

Well thanks for all your help everyone.