Symtoms of a Bad EGR ? - JeepForum.com

 
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post #1 of 3 Old 10-11-2010, 12:38 PM Thread Starter
michla
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1989 XJ Cherokee 
 
Join Date: Nov 2008
Location: Wasilla, AK
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Symtoms of a Bad EGR ?

1989 XJ w/4.0.

What are typical symptoms of a troublesome EGR ? New one installed, I suspect a defective unit.

I remember something that it will start cold but hestitation until warmed up?
Midrange RPM is most affected.

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post #2 of 3 Old 10-11-2010, 08:24 PM
Curly5759
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1997 TJ Wrangler 
 
Join Date: Apr 2009
Location: Arizona
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An egr should only be open above idle, on a warm engine.
If it opens at idle/partly open= stall or very rough running
If it doesn't open = may cause pinging on acceleration, Nox emissions will increase.

Apply vacuum to the valve with the engine idling. If it stalls or is noticably rougher, then you know that it is 1) closed at idle and 2) the vacuum diaphram is ok.
Your PCM applys vacuum at the correct time by energizing the vacuum solenoid in the vacuum line. Check for vacuum at the valve at idle, there should be none. If you always have vacuum, then the solenoid is defective or there is a problem with the PCM

curly

I start what I finish!
77 Jeep Cherokee S
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post #3 of 3 Old 10-11-2010, 09:40 PM Thread Starter
michla
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1989 XJ Cherokee 
 
Join Date: Nov 2008
Location: Wasilla, AK
Posts: 159
Thanks, Curly--that was great info !
Question: can that pinging, as if the EGV is never opening, be in the form of hesitation under heavy acceleration/high RPM??
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