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1991 GMC Safari van, 175,000 miles


KEWeyand's Avatar
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05-06-03, 04:20 PM   #1  
1991 GMC Safari van, 175,000 miles

It was running okay but I changed the plugs, wires, dist. cap and rotor and oxy sensor. Now it idles badly and wants to die at acceleration when cold. When warm, it runs okay but still wants to die at idle. I changed the Oxy sensor again but no change.

This is driving me nuts. Help!

 
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05-06-03, 09:21 PM   #2  
This might be a dumb question,but did you gap the plugs?.Also recheck yourself ,which you probably already have,to make sure you didn't knock off any vacuum lines.

 
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05-07-03, 06:04 AM   #3  
Joe_F
I agree. Check your work again.

 
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05-20-03, 02:41 PM   #4  
Well, I re-checked the work, put in another set of new plugs (no fun on this vehicle) and a fuel filter. Checked for any loose wires or vacuum lines. Everything looks okay but no change in performance.

My wife now tells me that the vehicle ran great for a couple of days after the original tune up but then started acting up. So it may not have had anything to do with the work I did.

I ran the vehicle through Oregon's DEQ check station and it failed due to high NOX readings.

Any other suggestions? Thanks much in advance.

 
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05-20-03, 03:34 PM   #5  
darrell McCoy
how long since any EGR svc or check? Saw a 91 astro, ran same way. Cleaned ports and serviced EGR valve and it was OK.

 
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05-21-03, 04:16 AM   #6  
Joe_F
Agreed. High NOx is an EGR system problem. Probably have a stuffed valve and clogged ports.

 
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05-21-03, 02:19 PM   #7  
Thanks guys!

Can this item be successfully cleaned? If so, how? Or do I need to replace it?

 
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05-21-03, 05:05 PM   #8  
darrell McCoy
remove and see if there is any buildup in the ports first. You may have to install a new one and is not a big job.

 
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05-22-03, 06:32 AM   #9  
Joe_F
I agree. If it's badly stuffed, it likely has to be replaced. Common problem and any parts store has it available.

You might choose to buy the EGR gasket with the built in screen (if available for this application) so as to slow down (not prevent) jamming the new valve again .

 
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06-02-03, 09:38 AM   #10  
Well, apparently the EGR valve replacement fixed the problem. It's running perfectly now but for some reason, nothing changed until about 2 days after the valve replacement. Good now though. Thanks for all the help.

 
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06-02-03, 09:48 AM   #11  
Joe_F
Sure thing. Make sure to use the gasket with the built in screen if available for this application. Any parts store has them. That will slow down (not prevent) carbonization of the new valve.

 
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07-10-03, 08:13 AM   #12  
FYI - the final chapter.
After replacing the EGR valve, the vehicle still did not pass Oregon's DEQ, again because of NOX. The final fix was a new catalytic Converter. Passed with flying colors and is now running great. Still uses no oil at 175,000 miles. Is this common for this engine?

Thanks again for all the help!

 
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07-10-03, 08:27 AM   #13  
Joe_F
The catalytic converter fixes the symptom, not the root of the problem in all honesty.

What were the readings before and after the cat replacement?

 
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07-17-03, 09:31 AM   #14  
I couldn't find the actual resullts from the Oregon DEQ tests but as I recall, the state maximum on NOX is 3.0. After the first test, the results were at approx. 6.0. After replacing the EGR valve, it went to approx 4.0 and after replacing the Cat, it dropped again to approx 2.0.

I hope this helps. Let me know if there is anything else that I should do.

 
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07-30-03, 12:47 PM   #15  
Oh, yes. My wife, who usually drives this rig, reports that it tends to die at idle when the air conditioner is on. Otherwise, seems to idle and run fine.

Any comments, hints, fixes? Thanks.

 
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07-30-03, 01:20 PM   #16  
Joe_F
Any vacuum leaks?

 
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07-30-03, 01:59 PM   #17  
None that I could detect.

 
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07-30-03, 03:58 PM   #18  
jtackett
Possibly a bad throttle position sensor?? Can't remember if it spits out a code when bad or not. As far as miles go-my '89 Astro (same 4.3 engine) had 336,000 miles on it when I sold it for $2000. Ran like a top, good compression used maybe a quart between oil changes (every 4000 miles). Can't say enough good things about that 4.3!! Jeff

 
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08-15-03, 06:17 AM   #19  
Well, it finally appears to be fixed. It was running worse and worse. I replaced the Idle Air Control Valve but that had no effect. Finally gave up and took it to my mechanic. They replaced the MAP sensor and the fuel pump.

Not cheap but finally fixed.

Anyone looking for a good, honest mechanic in the Portland, OR, area, Lentz Automotive.

Thanks.

 
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08-15-03, 08:44 AM   #20  
Joe_F
Nice to hear there are honest guys out that way too. I know a mechanic or two out there (however, I live in NYC).

 
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