I've recently had my Stabilitrak light and engine light come on, took my car to the dealer and they tell me the number one cylinder is misfiring. The spark plug was oil fouled which meant there was an internal engine leak and with my car having 188,000 miles they suggest a new engine. $6545.50!! Who has money for that? They replaced my spark plug and said it'd just be a temporary fix. Two months later I'm having the same issue but with my number 7 Cylinder misfiring. I went to two different mechanics to get an opinion and see why my options were. The first one says "I'd start by placing new plugs and wires in it and go from there", I know that isn't the issue so I went to another guy. He tells me I have a few options. 1, I can have a reman. engine put in by him for $4200. 2, there's some oil fouler I can put on my plugs and it'll keep them from becoming fouled and I can drive it til the cows come home. 3, he can put some cleaner in the engine to fill up the cylinders and leave it overnight and let it clean the gunk off them and release my rings and hope that fixes the issue. Or 4, I can sell it.

Are these my only options? Has anyone else had the same issue and can help me out? My car is in mint condition other than the engine and I really don't want to get rid of it.

Any help would be greatly appreciated!!
— Josh

 

I'd go reman, and then deactivate the AFM. The problem, IMHO, is a design flaw with the AFM system. That's why I don't own a 5.3 GMT900 truck.

 

"there's some oil fouler I can put on my plugs and it'll keep them from becoming fouled and I can drive it til the cows come home"
Sounds like a fix. Wonder if it effects performance/gas mileage?

Couple of questions if you don't mind.
Curious how long does installing a new plug last until it becomes fouled enough to set misfire code?
Do you have any cylinder compression data.?

 

I bought it in January of this year An didn't have an issue with misfiring until probably June or July. But I just had the issue come up again last week so I replaced the plug and then again 2 days ago. And I do not have any Cylinder compression data. Also I asked about the oil fouler causing any issues and he told me there weren't any, I just find that a little hard to believe–not that it isn't true!

 

if the cylinder have compression, the afm lifters are ok.
if the plugs are oil fouled, the oil control rings are gunked up from the afm pressure valve in the oil pan spraying oil onto them.

gm has a tsb to install a shield of the valve in the oil pan. remove all spark plugs and soak in a combustion chamber cleaner and replace the valve cover to improve pcv flow. hopefully, this will stop oil consumption(are you noticing that?) and stop plug fouling. 9 hours labour.

aside from that...the afm system must have clean oil...the extended oil change intervals and resulting dirty oil are killing the afm lifters....they collapse and cause a misfire in the afm cylinders.

 

I have noticed a slight bit of oil being used. It's not a major amount and just barely enough to notice. There's not any leaks whatsoever and I've even had to have the oil pan resealed a few months before, so its obviously being burned. I make sure to change my oil EVERY 3000 miles.

If I were to have the valve cover replaced instead of doing it myself, how much does it usually cost? And what brand chamber cleaner would you suggest?

 

if your not going to put the shield in, you might as well doing nothing. without the shield, your just cleaning it up till it happens again.

 

That's what I meant, to have someone replace the shield for me how much does it cost? Or is it easy enough I can do it myself?

 

just the afm shield in the oil pan...Its about 4 hours labour if you have 4wd. the front diff has to come out. 2wd are much easier...maybe 1.5 hrs labour.

 

I had the same issue. Stability Traction code and engine light blinking on dash. Truck loosing power and running crappy. Code reported that throttle sensor was bad and cylinder 4 misfiring. We replaced the throttle sensor replaced the fuel injector and replace the spark plugs, we also replaced fuses and brake switch. Nothing worked until my mechanic discovered that the valve lifter in cylinder 4 was bad. In the process of getting that replaced now. It is going to cost me $1200 at a private shop. Dealership was saying I needed a new engine $7000 unreal!