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Random misfire

fairoaksbp

By fairoaksbp
in Ask A GM Technician

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fairoaksbp New Member

fairoaksbp

Posted
Posted

2003 Yukon KL 5.3

Random misfire cylinder #4 and #6 are missing

Install the new plugs, wires, swarp the fuel injectors, disconnect cat, change the maf sensor, replace the pcm ,install the new engine as the dealer recommded. But still the same problem, the engine misfire with no power.

Any ideas I already spent 3500 dollars.

Mr. Smith Enthusiast

Mr. Smith

Posted
Posted
2003 Yukon KL 5.3

Random misfire cylinder #4 and #6 are missing

Install the new plugs, wires, swarp the fuel injectors, disconnect cat, change the maf sensor, replace the pcm ,install the new engine as the dealer recommded. But still the same problem, the engine misfire with no power.

Any ideas I already spent 3500 dollars.

 

 

 

 

 

You changed an engine for a random misfire? I hope that was a mistype.

HyperBuzzin Enthusiast

HyperBuzzin

Posted
Posted
You changed an engine for a random misfire? I hope that was a mistype.

 

 

 

If he spent $3500, I don't think it's a mistype.

But he did say "As The Dealer Recomended" which I do think is misinformation on the dealers part.

95Sierra2500 Senior Enthusiast

95Sierra2500

Posted
Posted

I see alot of base steps to fixing the problem, but I don't see anything about replacing coils, which I would have done BEFORE replacing injectors...It sounds like his dealership is taking him for a ride.

  • 2 months later...
jotack New Member

jotack

Posted
Posted

Im having this same problem with my 99 silverado 5.3 its weird though because it would barely start the other day and I went out tonight and its like there is nothing wrong. I replaced the plug wires, fuel filter, fuel pressure regulator, and ran 2 cans injector cleaner through it any ideas?

jotack New Member

jotack

Posted
Posted

I forgot to say that it misses at low rpm, and to get it to smooth out you pretty much just have to punch it to the floor. Ive had a bad cat for about two years, but never caused any problems. I first thought it was bad gas and use lucas engine treatment, and it worked for 2 weeks but the problem came back and it was worse. I took it to a garage, and he said blocked injectors, so he put gm top engine cleaner in it, it seemed to help, but then it didnt. I dont know whats going on. I was told to go to a gm garage and get them to read it off of their computer, because it is more accurate. Is that true? And again any ideas would be helpful.

diehrd Enthusiast

diehrd

Posted
Posted

A guess as any forum reply can be, , I would say wires and or coil packs.. To check coil packs on your own swap the misfiring cylinders with 2 that fire correctly. And re scan do the same with the wires ..

jotack New Member

jotack

Posted
Posted

no i havent scanned the injectors, but i did put new wires on. The weird thing about this problem, is I went out today and it started just fine. It seems to be running really good, and the only problem at the moment is when I start it, it stumbles for a minute or so and will smooth out. also if you give it some throtle it will also smooth out and seem just fine. About scanning the injectors should I go to a dealer for that?

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