Questions and Answers

Daewoo Idle Problems Q. Hi Vincent! I drive everyday to the office a 1996 Daewoo Espero; 1.5 liter DOHC fuel injected gasoline engine; with ABS; 5 speed manual transmission and has about 41,000 miles on it. My problem is with its erratic idling. Let me cite your some instances of which I don't know if they're inter related or not.

First: I have noticed that every time I let go of gas pedal after revving engine, idle will drop down to a point where it will almost stall with lights flickering and all (dashboard lights, car lights etc.) then it comes back quickly to normal idle again. This is especially true during stop and go traffic when there is continuing play between the clutch and gas pedal.

I sometimes I have to put extra gas so as not to stall the engine when idle drops suddenly. I have noticed also that idle drops significantly every time I make hard turns when I try maneuvering in tight spots (sometimes I stall the engine this way!)

Is this because of the ABS?? Wheels?? Idle speed control?? I just had the fuel injectors cleaned, new spark plugs and all. Alternator Assembly, is also new plus I had a new battery installed.

Second: There were occasions when idle is abnormally high (more so during stop and go traffic) When my car comes to a stop and I press the brake and clutch pedal to either change gear or go into neutral, idle speed will shoot between 1,200 to 1,500 rpm. But when I tap the gas pedal upwards with my foot, it mysteriously comes back to normal! (about 850-900 rpms) Initially, I thought it was the gas pedal/ throttle cable and I had it adjusted and put on a new clip. It went on fine for some time but then it came back on again!

Third: Lately, I have experienced twice my engine suddenly die down after just going a few hundred meters from a cold start. It usually runs normal again when engine it seems is between normal to peak operating temperature already.

Are all above problems related?? Is this a fuel system problem?? There was a time my car was reeking of gasoline (even from inside!) after filling her up. My mechanic says it was the breather hose and he had it adjusted tight. He also had the fuel pump cover adjusted tightly (located from under the rear back seat) The smell was gone but sometimes I can still swear that there's still a hint of gasoline somewhere though I can't exactly point where.

Please Vincent!! I have already racked my brains trying to figure out what my problem is.

Thanks!!
Mike

A. I think all of these things are related. It sounds like the Idle Speed Control Valve (ISCV) is not working properly or is sticking. The reason it stalls on turns is that there is a pressure switch in the power steering line that tells the computer to compensate for the extra load. If the ISCV is not working correctly, it can't compensate and the engine stalls.

Another possibility is the Engine Coolant Temperature (ECT) sensor. If this is reporting an incorrect temperature to the computer, it can cause idle fluctuations and stalling as well.

What I would do is have your mechanic do a through cleaning of the throttle chamber and ISCV and it's passages. There is an 80% chance that the cleaning alone will fix the problem.

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