1989 Chevy S-10 Rough Idle When Warm

Tiny
DESERTDOG8087
  • MEMBER
  • 1989 CHEVROLET S-10
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 71,000 MILES
My 89 Chevy S-10 has 71,000 miles.
The engine runs good when it is cold, but
when the engine warms up it seems that the idle lowers and the engine starts to run rougher than when I first start it up.
The engine begines to run so rough that it acts like it's going to stall but does'nt. I've replaced the Air idle controll valve, new ECM, new plugs and wires and an O2 sensor. The EGR valve seems to be OK. I've had a vacuum check done on the valve (EGR) and it seems to be operating properly, but i'm unsure if it could be bad. When I hook up a vacuum gauge to it the idle does change. If I do it while it is could it starts to run as it would when it warms up. What would be the problem is there something that I might be over looking? What might the problem be?
PLEASE HELP!
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Wednesday, April 22nd, 2009 AT 4:19 PM

5 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
Try this, remove the EGR and check to see if it is plugged with carbon. Let me know what you find. Also, make sure the intake isn't plugged with carbon where the EGR mounts. Also, check the hoses going to it to make sure they are not plugged.

Let me know what you find. You should also check the valve when it's off to make sure the valve is moving and sealing when closed.
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Saturday, May 2nd, 2009 AT 2:30 PM
Tiny
DESERTDOG8087
  • MEMBER
Ive Checked the EGR valve to see if there was any carbon build up. The area where the EGR valve seats seems to be fine. I don't see a whole lot of build up.
I've checked all the vacuum lines to see if they were plugged. They seem to be clear. I've also checked all the vacuum inlets going into the throttle body for any heavy build up. I found that the line for the PCV valve had some heavy build up, but was able to clean it out with some throttle body cleaner.? Would a worn pcv valve cause this problem. The reason i'm asking is because when I pull lose the pcv valve line off the throttle body the idle seems to smooth out quite a bit and the idle comes up just a hair. How would I know if the electronic vacuum sensor is working properly?
I've taken some throttle body cleaner and sprayed the surrounding areas of the EGR valve really good and also cleaned inside where the valve sits. The inside of the throttle body behind the EGR valve did'nt appear to have alot of carbon- just minor amounts. I sprayed throttle body cleaner into this area just incase there was. I also sprayed the area around where the injectors spray and around the IAC
valve and just about any where else I thought that minght be effecting the vacuum air flow. It's still idling rough when its warm but seems to be trying to run a little better that's why I was asking if the pcv valve might have a part in this. That's why I'm also asking about the electronic vacuum sensor. You pull the vaccum lines off and I've got vacuum on one side but not the other. Oh! The egr valve does seem to be moving fine but, it does make a slight rubbing sound.
I'm working at it little by little but, I know that the issue will be terminated eventually.
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Thursday, May 28th, 2009 AT 11:18 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
The PCV can cause a rough idle. Are you sure it is working properly? Also, did you check the intake for leaks? The intake gaskets on these vehicles have a history of leaking.
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Friday, May 29th, 2009 AT 7:03 AM
Tiny
DESERTDOG8087
  • MEMBER
What would be the best way to check for leaks around the intake?
I'm not really sure if the PCV valve is working properly.
It was just a thought.
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Wednesday, June 3rd, 2009 AT 9:45 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Many people will spray starting fluid or a carb cleaner around the area. IF there is a leak, the RPM's will increase. My only concern is if you spray an area that is hot enough, the sprays can catch fire. Just be careful and have a fire extinguisher near.

As far as the PCV valve, when you shake it, you should be able to hear a check ball rattle inside. If you do, it's good.
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Wednesday, June 3rd, 2009 AT 2:03 PM

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