EGR Problems?

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  #1  
Old 04-30-02, 06:23 PM
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EGR Problems?

OK, a new problem in my old raggedy Suburban. (1989, 5.7 L, TBI, K engine)
I'm getting all the symptoms of EGR problems. My problem is I'm not getting a code from the computer. I can cause codes by disconnecting EST or Knock Sensor (42 & 43) but I cannot create an EGR (32) code even by disconnecting the EGR solenoid and/or the valve and driving. The solenoid electrical is getting power on both wires when engine is running at operating temp. Power only to pink wire with just key on. Is it possible for a particular circuit (EGR) to burn out on the computer? Anyone come across this problem before?
Any help would be appreciated!
 
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  #2  
Old 04-30-02, 10:25 PM
knuckles
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In order to force a code 32, you have to disconnect the EGR solenoid, then drive the truck under the following conditions:

The ECM will check EGR operation when:


Vehicle speed is above 50 mph.
Engine vacuum is between 40 and 51 kPa.
No change in throttle position while test is being run.
 
  #3  
Old 05-01-02, 05:41 AM
Joe_F
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I agree with Knuckles. However, what is the actual problem you are experiencing and why do you think it is EGR related?

Did you inspect the EGR valve for carbon deposits?
 
  #4  
Old 05-01-02, 10:53 AM
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OK, ran it on cruise at highway speeds. Got a code 43, but still no code 32. Performance did not change. EGR valve and solenoid are new, port on manifold is clean.
 
  #5  
Old 05-01-02, 12:10 PM
Joe_F
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Check my signature file for a link to autolibrary.org. They should have the knock sensor test procedure in there.
 
  #6  
Old 05-01-02, 03:15 PM
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knock sensor's been bench tested and is fine, also has new EST.
 
  #7  
Old 05-01-02, 07:32 PM
Joe_F
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Again, what is the actual problem? Stalling? Hesitation? Emission failure?

How does it run when you plug the vacuum line with a screw and then drive it? I did this on my grandparent's 89 Cavalier and sure enough, the miss/hesitation went away. The valve was packed with carbon (new one on order )
 
  #8  
Old 05-01-02, 10:30 PM
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Joe-
Symptoms are surging at highway speeds, RPM's taking a minute to come down from highway exit, detonation(Knock), then poor idle...all the basics except seems to run rich when warm idle. Engine RPM surges slightly like something is trying to pull it correct. Problems start when loop closes. All sensors have been bench checked, except new O2, and new EST.
If I could find a mountain here in Louisiana, I'd push it off. I'm just about ready to put a 160 thermostat on it and just keep it in open loop!
 
  #9  
Old 05-02-02, 03:47 AM
Joe_F
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Nah, not that bad yet .

Again, what happens when you take the EGR out of the picture? Run better? How does the valve look and operate? If you can hear crusting of carbon when you work the diaphragm by hand or with a Mityvac pump, it's clogged with carbon. Clean it, but most times, replacement is necessary.
 
  #10  
Old 05-04-02, 04:37 AM
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When I disconnect EGR Solenoid and/or valve this is no difference in performance.

God I miss my old GTO! Fuel, Vacuum and Spark was a lot easier in the good old days! (and much, much faster)
 
  #11  
Old 05-05-02, 01:20 PM
Joe_F
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If disconnecting the EGR valve has no issue on performance, the problem is not likely there.

Try unplugging the solenoid and seeing if that changes anything.

That being said, an old Pontiac beats an old Bowtie anyday in my book . However, I DO like Chevrolet products
 
  #12  
Old 05-06-02, 01:45 AM
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I've always liked GM. Like you I prefer the Pontiacs. Lately the chevy's aren't looking too good to me! LOL

I gave up and put it in the shop. I have reached the end of my and my test equipments ability. I'll let you know what I find. I believe I've got a bad wire(s) to the computer. Some times I can't make it fail, some times I can't make it run right!
 
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