2007 GMC Yukon XL

[Mizz0313]

Here is my 07 xl i purchased a month ago to replace my 04 i built a few years ago. 04 is in great shape but is getting to the point of repairing rust, the 07 doesn't have any rust and i got it for a nice price as it used to be a limo. 07 had a random misfire p0300 and a 02 sensor code, after doing a tune up and code still being present i decided to pull valve covers off to check for collapsed lifter. All valve train components moved so that confused me a bit. I have read alot about afm so i know what im dealing with as what to look for and so on, light tick from passenger side but like i said all valve train parts move. Started pulling motor apart to get heads off before vacation and was able to check cam from valley and wanted to get someones opinion on the condition of cam. I know i will have to pull heads to know for sure but would like to get thoughts on it so i can decide what route i want to take with this build. If cam is badly worn i would do a dod delete, if cam is okay i would possibly do GM TSB updates and build motor back up and see how it does. Thanks! All advice and opinions welcomed.

 

[Mizz0313]

Scan tool also showed 121 counts if misfires on cylinder7. Misfires on cylinder 2 also but not nearly as much as 7

 

[swathdiver]

At the least your lifters are worn and causing the misfires. Do the delete and the oil pump while it's apart. You sure though that the misfires are not coming from plugs/wires/coils or injectors?

 

[Mizz0313]

Not 100% sure about coil or injector. I did replace plugs and wires but didn’t get around to checking coil or injector, I know I should have but I let the internet persuade me into just pulling it apart after seeing so many of these lifters failing. Kind of flabbergasted when i pulled valve covers and everything looked to move freely. Should have just tested coils at least. Truck ran very rough at idle, exhaust smells really bad and black smoke out of exhaust when driving.

 

[swathdiver]

So what are your plans? Delete or rebuild AFM with the latest and greatest parts?

 

[Mizz0313]

I have been on the forum for over a month now and have seen you speak on this on almost every related post. So I’ll ask you, has the gm tsb actually fixed the issue? Tons of info on the delete and a lot of happy owners once done but not that many people talking about the problem being resolved doing the tsb updates. I would put stock parts back in if cam checks out good but don’t know if it’s worth it if it can just fail again. I have been looking both routes and cost seems very close for both I guess I just have to decide if I want to yank rad out and pull the cam.

 

[swathdiver]

I have been on the forum for over a month now and have seen you speak on this on almost every related post. So I’ll ask you, has the gm tsb actually fixed the issue? Tons of info on the delete and a lot of happy owners once done but not that many people talking about the problem being resolved doing the tsb updates. I would put stock parts back in if cam checks out good but don’t know if it’s worth it if it can just fail again. I have been looking both routes and cost seems very close for both I guess I just have to decide if I want to yank rad out and pull the cam.

As I was looking for one of these I starting asking friends who owned them about them. One had AFM fail and it took out the engine. Since his wife was pregnant with their 5th or 6th at the time, he went ahead and got something bigger to handle his quiver full of rugrats. Lots of posts about the horror stories on all these forums and the first thing many do is turn it off.

I did the same. Mine worked perfectly though not often because of the vehicle's weight. I was also going to physically delete but my wife found a way to spend that money so I had to put it off a while. Then I got hold of the service records and low and behold, right before I bought it, all the lifters were replaced, the valve cover and VLOM. The design of the latest parts are greatly improved and the biggest enemy of AFM is dirty oil. So I'm actually tossing the idea around in my head to turn it back on.

But let's say a regular lifter failed or a cam lobe wiped out. I would probably go for the horsepower and torque and delete AFM for a mild camshaft upgrade. Despite how cool it may or may not be, it still adds complexity and more stuff to fail down the road. Then again, most folks run them 200K plus and never have an issue, even the older ones before the updates.

You'll just have to settle in your mind what's best for you and your family.

http://www.enginebuildermag.com/wp-...es/03_01_2012/986163348GMGENI_00000054947.pdf

 

[Mizz0313]

I have got the driver side head off the truck today and found a bent push rod on cylinder 7. The rollers on the lifters are smooth and have no pitting or signs of damage. Have to go back tomorrow and get pics of lifters as I’m not sure what they look like when collapsed. Piston also showed no signs of damage from push rod so I’m not sure what my issue is yet. Will keep you updated as I pull passenger side off and see what things look like.

 

[Wolfbraid]

Not 100% sure about coil or injector. I did replace plugs and wires but didn’t get around to checking coil or injector, I know I should have but I let the internet persuade me into just pulling it apart after seeing so many of these lifters failing. Kind of flabbergasted when i pulled valve covers and everything looked to move freely. Should have just tested coils at least. Truck ran very rough at idle, exhaust smells really bad and black smoke out of exhaust when driving.

Swap the coil to another cylinder see if the misfire moves. If it doesn't swap the injector. I'm having a similar issue with another car I own..(Deville) It's a long road of trouble shooting for me.

EDIT: nevermind just saw the recent update..

 

[Mizz0313]

Thanks buddy. I should have diagnosed a little further as I saw my number 7 plug was not all the way in the block, which I think would cause misfires, but not bend a push rod? So it’s nice I tore it down anyway as I would have never diagnosed that bent rod. Just weird everything else looks good. Won’t know more till I get passenger side off.