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2008 sierra p0301

Dalfan85
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Dalfan85 New Member

Dalfan85

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Hello. I'm looking for some help. I've owned several chevy and gmc vehicles.  From 97 gmc yukon suburban,  2006 trailblazer ss, 2012 silverado,  and i have a 2008 sierra. Last week i was up in Canada and had temperatures between -20 and -40. It was terrible lol. On my way home my check engine light started flashing and my stabilitrack light came on. I was about an hour and a half from home when this happened.  I always carry a code reader in the truck so i checked the codes and it was p0449 and p0301. I changed the vapor purge valve and the evap canister solenoid and it took care of the 449 code. Then i swapped the spark plug, plug wire, then coil pack from cylinder 1 to cylinder 3 and it still showed cylinder 1 misfire. So i changed the fuel injector and it still showed p0301. The spark plug from cylinder 1 definitely had gas on it and was kind of black with a build up on it but didn't look like carbon or oil. The truck kinda stutters and idles rough especially when i put it in gear. I appreciate any help.

Supreme Pizza Senior Enthusiast

Supreme Pizza

Posted
Posted (edited)
2 hours ago, Dalfan85 said:

Hello. I'm looking for some help. I've owned several chevy and gmc vehicles.  From 97 gmc yukon suburban,  2006 trailblazer ss, 2012 silverado,  and i have a 2008 sierra. Last week i was up in Canada and had temperatures between -20 and -40. It was terrible lol. On my way home my check engine light started flashing and my stabilitrack light came on. I was about an hour and a half from home when this happened.  I always carry a code reader in the truck so i checked the codes and it was p0449 and p0301. I changed the vapor purge valve and the evap canister solenoid and it took care of the 449 code. Then i swapped the spark plug, plug wire, then coil pack from cylinder 1 to cylinder 3 and it still showed cylinder 1 misfire. So i changed the fuel injector and it still showed p0301. The spark plug from cylinder 1 definitely had gas on it and was kind of black with a build up on it but didn't look like carbon or oil. The truck kinda stutters and idles rough especially when i put it in gear. I appreciate any help.

 

 

 

What year/make/model of vehicle are you working on?

 

If its the 2008, you can run a compression test, but that can be inconclusive if you have the AFM problem. You would start with that test, and if it fails - you can stop testing. If it passes, you would want to pull the valve cover and check the rocker arms on that cylinder. Make sure that both rockers move properly for 30 seconds with the engine running. Lifters and fail intermittently and fool a compression tester.

Edited by Supreme Pizza
shakenfake Senior Enthusiast

shakenfake

Posted
Posted

Lifters will fail and wipe out the cam lobes causing misfire. Recommended to replace all lifters and the cam shaft as well as get a tune to remove the AFM portion.

Supreme Pizza Senior Enthusiast

Supreme Pizza

Posted
Posted (edited)
11 hours ago, Dalfan85 said:

Yes it's a 2008 sierra 5.3. What is the afm problem?

 

 

It would take a long time to explain everything there is to know about it, but here are the basics:

 

GM has designed a motor that will stop 4 of the cylinders from firing, by basically shutting off the lifters.

 

The design was faulty, and if there are any problems in the system - especially oil pressure related, then the lifters fail.

 

If any lifters fail, then you have to figure out specifically why, and then pull the head(s) to replace the lifters.

 

To prevent the failure, you have to disable the system before any damage happens.

 

I had to replace parts on my oil pump and pull the head to fix mine. (it was already broken when I bought it)

 

 

If you want more info, you can search "AFM" "DOD" or "DFM" along with the word "failure" or "problem" on this forum, or google.

 

 

To disable the system, you can mail the ECU in to a special shop and have it reprogrammed ($50).

 

or buy one of these:

 

https://www.amazon.com/gp/product/B07TTRC3MM/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

 

 

 

Edited by Supreme Pizza

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