My '01 Lanos has 178k mi, recently replaced EGR valve. Fuel filter, spark plugs and cables were replaced at the same time. Air filter was replaced at the last oil change. The CEL is not on and there are no codes stored. My issue is this: about four miles into my drive to work, there is a traffic light at which I must often stop. The engine settles down to idle speed, then stumbles to the point of almost dying (once), then idles smoothly again. If I keep going without stopping, the engine runs normally - no stumble. This obviously happens when the engine is not quite up to operating temperature.
Any ideas?
Stumble
Moderators: daewoomofo, Moderators Group
Re: Stumble
does this occur with the air con on?
and is it an automatic?
and is it an automatic?
~2.0L Lanos~EHPAS~H&R Springs~KYB/GTS Shocks~
Re: Stumble
A/C off, man trans. It idles smoothly when started cold and does not stumble when I stop after about 6 miles. It seems to be linked to being not quite up to full temp.
Re: Stumble
hmmm once you driving it should only take about 15 min to get op temp...Lanos01 wrote:A/C off, man trans. It idles smoothly when started cold and does not stumble when I stop after about 6 miles. It seems to be linked to being not quite up to full temp.
Daewoo Lanos SX,
1.6 16v DOHC,
1.6 16v DOHC,
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daewooluvr
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Re: Stumble
Check all your vacuum lines, sounds like you have a leak.
Re: Stumble
I disagree a vaccum leak is constant and will never go away. Unless its a controlled vaccum leak (like a purge solenoid or idle speed control). In that case then the fault occurs when the sensor who provides the "vaccum leak" fails. Otherwise your car would be idiling high all the time, and probably have 02 sensor lean codes present or pending.
If I had to guess I would say your problem lies in the idle speed control circuit, or evaporative emissions. But I would say option #1 is the most probable cause. With your mileage it would not be surprising to be a faulty PCM idle driver as that thing has been running a 12v 6amp driver for quite a while now.
Check for proper operation of the idle speed control, make sure it is clean, and perform idle relearn and see if this corrects the issue.
If I had to guess I would say your problem lies in the idle speed control circuit, or evaporative emissions. But I would say option #1 is the most probable cause. With your mileage it would not be surprising to be a faulty PCM idle driver as that thing has been running a 12v 6amp driver for quite a while now.
Check for proper operation of the idle speed control, make sure it is clean, and perform idle relearn and see if this corrects the issue.
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Doral Auto Care
5171 NW 36th
Virginia Gardens, FL 33166
(305) 871-1121
BS Mechanical Engineering 12/12 (FINALLY!)
ASE Certified:
Engine Electrical
Engine Performance/Advance
Brakes & ABS
Air Conditioning
Re: Stumble
Thanks for the responses. Sorry about not getting back sooner, been busy. The stumble went away on its own. About a month before I posted the problem, I had the AC serviced because it was not blowing very cold air. The refrigerant was pulled out so I could replace the compressor and receiver/drier myself. According to the service manual, AC system pressure is one of the inputs for the idle speed setting, and I think over time it reset itself. Does this make sense? Thanks,Trey, for mentioning the idle speed setting - that prompted me to make the connection and look it up in the manual.
Re: Stumble
wow, who knew? Perhaps this is the reason some people have that extremely high idle with the air conditioner on? I think i saw a few other topics with idle issues?