P0304

[Blackbeard718]

So I tried new plugs and wires and even a coil pack on cylinder 4, still pulling code and missing. Plus the motor has a new loud nock from that side. I don't get it, was strong until now. Mechanic said possible cam and lifters and delete the dod. Any advice? I literally just bought the denali, still has paper tags but had to many miles for warranty.

 

[OR VietVet]

Anything mechanical or electrical, can be good one minute and bad the next. What is the back story on this? I am old, I don't have the memory I once had, if you did a story/question about this before. You show 3 responses and this new question/story counts as one of them. The knock is key. Sounds like a definite cylinder problem that could be even worse than a lifter. Needs a compression test. Why did you try new wires and plugs? Sounds like obviously had a code for a problem on cylinder #4. Strong till code? Strong even after code? Strong only after plugs and wires? Details man, details.....

 

[Geotrash]

So I tried new plugs and wires and even a coil pack on cylinder 4, still pulling code and missing. Plus the motor has a new loud nock from that side. I don't get it, was strong until now. Mechanic said possible cam and lifters and delete the dod. Any advice? I literally just bought the denali, still has paper tags but had to many miles for warranty.

What year Denali? How many miles?

If it has AFM, then #4 is an AFM cylinder, and I suspect a failed lifter given that you're hearing a loud knock. If you're mechanically inclined and have the tools, then you can do this repair yourself. I have done it and created a HOWTO thread here for how. If not, then choose a good indy shop. There is also a small chance that you can get the lifter unstuck by using a trick shown on YouTube. Some have had success with it. Even if you do, you're on borrowed time with that lifter.

Pulling the valve cover on that side will tell you if the lifter is the problem. You'll have a loose rocker and probably a bent pushrod on that cylinder.

 

[Blackbeard718]

I took it to a mechanic and he is going to do the AFM DOD delete cam and lifters. I picked out the cam with a little extra umph to get the big ol gal moving a little better.

 

[Geotrash]

I took it to a mechanic and he is going to do the AFM DOD delete cam and lifters. I picked out the cam with a little extra umph to get the big ol gal moving a little better.

Nice. Which cam did you go with?