The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - 99 Silverado 4.3 stuttering/starting problems.

bighaas79 · 11-05-2011, 08:58 PM

Without actually testing the truck this is what i'm seein. You have a cat goin bad and is plugged up, which is probably causing your misfire and the maf code. I would venture a guess that you may have started on the wrong end. I would have checked the cat and o2's first, based on the fact that the other codes can be resultant codes of other problems. And again without bein able to do tests, I'd venture a bet that your maf sensor was probably ok too. And to answer your other question, no cleaning up of cats they need to be replaced if bad. A warning they aren't cheap, and i would recommend factory cats, but if you go with aftermarkets, make sure you are getting a quality one that will work for the vehicle. Some of the real cheap universal cats can cause you just as many problems as the junk originals.

Just reread your o.p. when you did the gaskets, did you set the timing with a scan tool? Out of spec cam retard from the distributer can also cause these issues. Would make sure of that first i guess then proceed with the checking of the cat and o2's.

11-05-2011, 08:58 PM	#4
bighaas79 Registered User Join Date: Nov 2008 Location: manly iowa Posts: 390	Re: 99 Silverado 4.3 stuttering/starting problems. Without actually testing the truck this is what i'm seein. You have a cat goin bad and is plugged up, which is probably causing your misfire and the maf code. I would venture a guess that you may have started on the wrong end. I would have checked the cat and o2's first, based on the fact that the other codes can be resultant codes of other problems. And again without bein able to do tests, I'd venture a bet that your maf sensor was probably ok too. And to answer your other question, no cleaning up of cats they need to be replaced if bad. A warning they aren't cheap, and i would recommend factory cats, but if you go with aftermarkets, make sure you are getting a quality one that will work for the vehicle. Some of the real cheap universal cats can cause you just as many problems as the junk originals. Just reread your o.p. when you did the gaskets, did you set the timing with a scan tool? Out of spec cam retard from the distributer can also cause these issues. Would make sure of that first i guess then proceed with the checking of the cat and o2's.