Silverado Rough Idle and Hesitation

3GM · 10-05-2009, 01:52 PM

I have a 1995 4WD 5.6 ltr Chevrolet Silverado pick-up 1/2 ton.

Two problems which I think are related
#1 when first accelerating with a cold engine it hesitates this goes away once the engine is warm.

#2 Rough idle but not very often, happens with a cold or hot engine, will sometimes even stall out.

Here is what I have done, distributor cap, wires, plugs (all AC Delco parts), fuel filter, new pcv, air filter, set timing, run injector cleaner in gas and spray injectors and throttle body with cleaner.

No check engine light is on put it did come on and then go off. tried to get the computer read at Auto Zone but it is OBT1 and they can not read it.

Any help would be greatly appreciated!

**Raylo** · 10-05-2009, 04:21 PM

Intermmitent rough idle could be a sticking EGR valve. Don't know about the first issue.

3GM · 10-13-2009, 05:24 PM

Thanks

Cleaned the old EGR valve and both problems are better.

blakesduc · 10-15-2009, 07:23 PM

If the problem was resolved by cleaning the egr valve I would advise removing it again and starting the engine and let it run for a minute with it off be sure to keep your hand on the key and make sure the engine does not rev to high this will help remove the carbon deposits in the intake and head passages also run down to autozone and pick up a egr valve gasket with a screen on it this will help stop carbon deposits from ever reaching the egr valve a keep this from happening again .

10-05-2009, 01:52 PM	#1 (permalink)
3GM Registered User Join Date: Oct 2009 Posts: 2 OS: Mac os 10.4.11	Silverado Rough Idle and Hesitation I have a 1995 4WD 5.6 ltr Chevrolet Silverado pick-up 1/2 ton. Two problems which I think are related #1 when first accelerating with a cold engine it hesitates this goes away once the engine is warm. #2 Rough idle but not very often, happens with a cold or hot engine, will sometimes even stall out. Here is what I have done, distributor cap, wires, plugs (all AC Delco parts), fuel filter, new pcv, air filter, set timing, run injector cleaner in gas and spray injectors and throttle body with cleaner. No check engine light is on put it did come on and then go off. tried to get the computer read at Auto Zone but it is OBT1 and they can not read it. Any help would be greatly appreciated!

10-05-2009, 04:21 PM	#2 (permalink)
Raylo TSF Enthusiast Join Date: Feb 2006 Location: Maryland, USA Posts: 524 OS: XP Desktop, Vista HP Notebook, XP Notebook	Re: Silverado Rough Idle and Hesitation Intermmitent rough idle could be a sticking EGR valve. Don't know about the first issue.

10-13-2009, 05:24 PM	#3 (permalink)
3GM Registered User Join Date: Oct 2009 Posts: 2 OS: Mac os 10.4.11	Re: Silverado Rough Idle and Hesitation Thanks Cleaned the old EGR valve and both problems are better.

10-15-2009, 07:23 PM	#4 (permalink)
blakesduc Registered User Join Date: Oct 2009 Posts: 8 OS: xp service pack 2	Re: Silverado Rough Idle and Hesitation If the problem was resolved by cleaning the egr valve I would advise removing it again and starting the engine and let it run for a minute with it off be sure to keep your hand on the key and make sure the engine does not rev to high this will help remove the carbon deposits in the intake and head passages also run down to autozone and pick up a egr valve gasket with a screen on it this will help stop carbon deposits from ever reaching the egr valve a keep this from happening again .