2007 5.3 help needed
Moderator: Team
2007 5.3 help needed
I have an 07 Yukon that started running real rough/knocking and triggered the Stabilitack light and check engine light. Code came up stating missfire on #1. Did a compression test and I'm getting 70lbs on that cyl vs 170lbs on the other. This engine does have the AFM which I know is problematic. What's the next troubleshooting step(s)? I will replace the engine if I have to but if a new cam and lifters will do it, that will be obviously alot cheaper. Thanks guys.
VINCE 69 CHEVELLE
502 EFI/6SPD/3.90
502 EFI/6SPD/3.90
-
- Pro
- Posts: 234
- Joined: Fri Sep 26, 2008 12:00 am
- Location: Northeastern PA
Re: 2007 5.3 help needed
From a mechanical standpoint I would think a leakdown test would be the next step to test valve job / ring seal.
If you have good leak down numbers then a failed afm lifter could be causing the valve to not open far enough to get good cranking compression numbers.
Maybe then pop a valve cover and see if the intake valves are moving the same amount.
If not you'll probably need this.
https://www.summitracing.com/parts/cmb- ... /overview/
If you have good leak down numbers then a failed afm lifter could be causing the valve to not open far enough to get good cranking compression numbers.
Maybe then pop a valve cover and see if the intake valves are moving the same amount.
If not you'll probably need this.
https://www.summitracing.com/parts/cmb- ... /overview/
Re: 2007 5.3 help needed
I'd say drop in a couple lifters if you think that's all that is wrong, if you're changing the cam you might as well swap the engine with a low mileage junkyard deal it would be about the same amount of work.. By popping off a valve cover you should be able to see if the lifters bad based on rocker movement?
Re: 2007 5.3 help needed
check, check fuel injector, remove valve cover and check rocker movement or for excess lash (stuck afm lifter).
If its a lifter replace ALL afm lifters, and guides.
If its a lifter replace ALL afm lifters, and guides.
Re: 2007 5.3 help needed
just had the same problem with my 12 silverado check engine light and stab/track light coming on turns out that pack rats got into my truck and ate the wiring harness under the manifold to the vlom valve/lifter/oil/manifold so all 4 cylinder were not working and the truck was in
v4/limp home mode. I have had some repair work that we have done on other trucks that had 1 or 2 cylinders misfiring and it was the lifters and or the roller needle bearing in the lifters that gave out and ruined the camshaft.. time to fix and parts it was easily replace the engine with a new 1 reman one was about 3100.00 not installed repair was about 2300.00 or more
v4/limp home mode. I have had some repair work that we have done on other trucks that had 1 or 2 cylinders misfiring and it was the lifters and or the roller needle bearing in the lifters that gave out and ruined the camshaft.. time to fix and parts it was easily replace the engine with a new 1 reman one was about 3100.00 not installed repair was about 2300.00 or more
Re: 2007 5.3 help needed
I think on these you don't just throw lifters at them- the head needs to come off.
Re: 2007 5.3 help needed
Pulled the drivers head and removed the lifters. Pair of lifters on the left are from cyl 1, the one with low compression.
So I'll pull the other head also. My question is though can I replace the lifters with a new set of AFM lifters and just turn the AFM/DOD feature off? Trying to avoid pulling the radiator, cam etc.
So I'll pull the other head also. My question is though can I replace the lifters with a new set of AFM lifters and just turn the AFM/DOD feature off? Trying to avoid pulling the radiator, cam etc.
VINCE 69 CHEVELLE
502 EFI/6SPD/3.90
502 EFI/6SPD/3.90
Re: 2007 5.3 help needed
If the cam is ok, you can replace with ls7 lifters and do the whole AFM delete with the kit above from Summit. Yes, you have to turn off the AFM in the computer if you go that route.
Heat is energy, energy is horsepower...but you gotta control the heat.
-Carl
-Carl
Re: 2007 5.3 help needed
The interesting thing is, the last one I saw with a failed lifter, it passed a compression test just fine.
Pull the valve cover off and start the engine on the other bank, and you could watch the valves working and then after a few cam revolutions, one of the rockers would just stop moving. So the lifter would stay engaged for a few lifts, just enough to do good on a compression test, and then tap out.
Pull the valve cover off and start the engine on the other bank, and you could watch the valves working and then after a few cam revolutions, one of the rockers would just stop moving. So the lifter would stay engaged for a few lifts, just enough to do good on a compression test, and then tap out.
Re: 2007 5.3 help needed
My research has shown than the cam must be replaced if using non-afm lifters, which kinda sucks but whatever. Sure beats having to replace an engine like I was initially thinking!!!!!! (I hope lol).
VINCE 69 CHEVELLE
502 EFI/6SPD/3.90
502 EFI/6SPD/3.90
Re: 2007 5.3 help needed
cam does not need replaced no....you can run AFM or non AFM lifters on that cam.
but if you are keeping the cam, and putting new AFM lifters in...might as well keep it active...for better mpg anyway.
but if you are keeping the cam, and putting new AFM lifters in...might as well keep it active...for better mpg anyway.
too lazy to make power w/o boost
Re: 2007 5.3 help needed
The lobes for the AFM lifters have a different profile than the lobes for the non-AFM lifters. Two different lobe profiles on the same (AFM) cam.
Will it run with non-AFM lifters on the AFM lobes? Sure it will, but how well?
Ken
Will it run with non-AFM lifters on the AFM lobes? Sure it will, but how well?
Ken
Over the hill but still learning!
Retaining it is the hard part.
Retaining it is the hard part.
Re: 2007 5.3 help needed
it will run the same as if it had AFM lifters in it, when the AFM is not active
doesn't make sense IMO to do this...since you will have to still turn off the AFM in the computer, change lifter guide trays, and will have a cam that is limiting power
I guess if you were trying to cobble something together with free parts you had laying around, it could make sense.
doesn't make sense IMO to do this...since you will have to still turn off the AFM in the computer, change lifter guide trays, and will have a cam that is limiting power
I guess if you were trying to cobble something together with free parts you had laying around, it could make sense.
too lazy to make power w/o boost
Re: 2007 5.3 help needed
I stop by a buddies shop once in awhile, it's amazing what happens to the Hemi DOD when the customer cheaps out on oil changes $$