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Joined: Aug 2003
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CEG\'er
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CEG\'er
Joined: Aug 2003
Posts: 295 |
I've been having problems with my idle lately. When just sitting, it will surge between 1000 and 1500 RPM. I noticed lately, that if I leave my A/C on, even just on low, it will idle smoothly, although a bit high - somewhere around 1100 RPM. I DO have a CEL, P0171 - Bank 1 Lean. I have already replaced EGR valve, IAC valve, PCV valve, plugs, wires, MAF sensor, both 02 sensors, ECT sensor, TPS, and have checked battery and alternator, both good.
What I was wondering - Is there anything that gets bypassed when the A/C is turned on? Does anything open or close (EGR, IAC, etc.)? Are there any relays that might cause this? Advance says there's an EGR Valve position sensor on my car. I've never heard of this?
Thanks for any help!
Jonathan
'96 Contour Zetec MTX
208,XXX miles
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Joined: Jul 2002
Posts: 4,714
Scourge of the Master Debaters
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Scourge of the Master Debaters
Joined: Jul 2002
Posts: 4,714 |
I don't know about the A/C, but it sounds like you have a vacuum leak. It could be a gasket that's leaking. Have you tested for a leak around the manifold?
Last edited by hetfield; 08/26/04 05:22 AM.
Beer is my Gatorade.
Hooray Beer.
'98 "Sport" Pacific Green
'98 E0 SVT Silver Frost
Pictures
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Joined: Aug 2003
Posts: 295
CEG\'er
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CEG\'er
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Yea, I've been through numerous cans of WD-40, Carb Cleaner, etc. as well as hours of looking and feeling for anything that might be leaking. Nothing as of this point.
Jonathan
'96 Contour Zetec MTX
208,XXX miles
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Joined: Jun 2003
Posts: 14
New CEG\'er
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New CEG\'er
Joined: Jun 2003
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Any updates on this ???
I have same problem on my 4 cyl 96 mystique.
Idle is at 1100 rpms, then 1 second later, goes down to 800, and it keeps doing this ... Up and down, up and down, very regular pattern. Sometime it will die on me at a stop light.
Runs much smoother if I turn the AC on. Idles at 1000-1100 rpms and it pretty smooth.
No CEL.
I suspect a vacuum leak at the PCV but not too sure. I might look this week-end.
Could a misadjusted TPS do that ?
Any ideas.
iougs-
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Joined: Nov 2001
Posts: 1,176
CEG'er
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CEG'er
Joined: Nov 2001
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I have similar problems and I am suspecting Throttle position sensor. not too expensive I will be purchasing it soon..
An ounce of prevention provides a pound of cure!
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Joined: Aug 2003
Posts: 295
CEG\'er
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CEG\'er
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Originally posted by iougs:
Any updates on this ???
Not as of yet. I just put in a new Camshaft Position Sensor, with no luck. A buddy of mine said it sounded like it was missing. He's an old Chevy guy, but missing is still missing. I'm going to be looking closely at Coil Pack/Plugs next. I've got brand new plugs in it - Autolite Double Platinums, as well as the Autolite Professional or whatever plug wires. I'll update as I find anything new!
Jonathan
'96 Contour Zetec MTX
208,XXX miles
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Joined: Jun 2003
Posts: 14
New CEG\'er
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New CEG\'er
Joined: Jun 2003
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The more I think about it the more I think it is a vacuum leak ... Engine revs up, ECU sees the signal from TPS saying no throttle and cuts fuel as if decelerating, rpms go down, and the cycle keeps going and going.
One more observation:
this up and down thing does not happen when engine is fully hot. When engine is hot, idle seems to be very smooth even with electrical accessories on.
I dont't know if the original poster's idle smoothes out when the engine is hot though.
iougs-
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Joined: Aug 2004
Posts: 203
CEG\'er
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CEG\'er
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I have been trolling the boards for awhile and have found that people have been having idleing troubles with the autolite's double platinums. Maybe a semi-cheap fix would be to buy different plugs. Just a thought! 
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