'07 Sub 5.3, needs replacement engine, really?!?!

[mattt]

Original owner on an 07 Suburban 5.3, has around 150k on the ticker. Recently had a CEL come one & flash, along with a ding from the dash. #6 misfire code along with the P0449 that I'd been battling for a while. For the P0449, I replaced the valve on the rear crossmember, in front of the spare, but P0449 kept coming back. I reset the codes and both came back, but the CEL is no longer flashing and no ding any longer. CEL is solid on still.

I took it to a local dealer that has swung for the fence with me in the past, and they decided it's time for a grand slam, home run. They have recommended a complete engine replacement! Really??? For an 07 with only 150k? They are saying #6 has low compression.

In my family, I've have multiple(read 5) GM trucks & SUV's from 01 up thru 07 model year. Not ONE of them has needed an engine replaced, and all the others have higher mileage.

Is there something inherently wrong with the 07 drivetrain that the 5.3 longevity has completely gone away? If so, I'm very disappointed with GM and may have to reconsider my near future plans to buy a '15.

Back to the issue at hand.....I was thinking about doing the Seafoam clean, replacing #6 spark plug(dealer said it's fouled), and trying something else to get rid of the P0449. Anyone have some insight, BTDT advise, or suggestion how to get this not-very-old Suburban up and running well again?

 

[08grey]

Disable the Afm while your at it. Run that bad boy till the piston flies through the head.

 

[Gzes]

Betting they just want some easy money. Ws

---------- Post added at 01:13 PM ---------- Previous post was at 01:12 PM ----------

Worst case get a rebuild dontbuy a long block. But imo keep on truck in til it is about to go then rebuild

 

[mattt]

One thing I'm wondering....have others had the same recommendation and fixed the issue or had it fixed without going the replacement engine route?

If #6 is truly low compression, I'm wondering if the Seafoam will clean it up as to bring comp. back up....i.e. stuck rings, valve not sealing, etc. I did run across other low compression threads in 07+ vehicles when searching here prior to creating this thread.

How does the AFM contribute to this issue and how do you disable it?

 

[08grey]

You can buy a plug in thingy into the obd to disable. The dealer can disable or a tune can disable it.

Google 5.3 oil consumption for a explanation of how the Afm gums up the top of the motor.

We have a member here
that used a engine flush who had a oil pressure issue. I think it's called motor medic. You mix it with the oil run it then change it. Then use a good top end cleAner some new plugs n wires and see where it goes.

He also used another additive called risolene and had great results.

 

[mattt]

How many other replacement engines have gone in due to these issues? Did GM offer any out of warranty assistance?

Is there one thing, more than others, that I should be checking to find out why #6 supposedly has low compression. Should I assume stuck rings, valve issue, etc?

 

[mattt]

On the P0449 code, I've already tried the solenoid on the rear crossmember, and P0449 came back on after a short while. What other causes and/or fix are there for P0449? Tried a new gas cap already too. One thing I have noticed is when I fill the gas tank, it will occasionally, hiccup upon startup after filling the tank full. I'm guessing this might all be inter-related with the P0449 code.

 

[joshcarl]

as far as the P0449, here is a quick reference: http://www.obd-codes.com/p0449 regarding that. the truck will run fine with that code; it's only emissions related.

have you replaced the fouled plug yet? i have serious trust issues with stealerships. excessive blowby can/will foul the plug, but the cylinder not firing can also result in the same issue. you can try moving cylinder-related items to see if the misfire migrates with them. plug, wire, and coil would be the first 3 on my list. i can get you a schematic of the evap circuit if you need.

 

[mattt]

Interesting thing happened recently....P0449 is now gone, but has been replaced by P0496. I read about usual cause for P0496 and it appears the evap solenoid on the intake is the probable cause. I pulled the line off it with the engine running and it has constant engine vacuum. I'm still perplexed that 0449 has gone away and 0496 now took it's place. Anyway....it appears that evap solenoid should be normally closed so the engine is not putting constant vacuum on the tank or evap system.

I'm still all ears for what, if anything, worked to bring back a supposed weak cylinder compression wise? I suspect the engine is not shot, and needing replacement, but I'd like to hear a logical plan of action for this from someone who's been there done that. I know I'm not the only one.

It seems that driving with a #6 misfire may wash the cylinder down and/or the oil issues that I've read about from AFM may just have a thing or two stuck. I did have to drive it for a couple hundred miles with the #6 issue because I was in the middle of the Socal desert on my way home with no dealer or service anywhere in sight. After reading what I read on AFM, I'd really like to turn off the AFM, but I have no interest in a tuner. Someone said the dealer can disable it.....but will they......since they're primary concern is to maintain factory spec???

 

[joshcarl]

the evap solonoid should normally be shut, but the ECM does a self test of the circuit when you start the car to ensure the system is operating properly. again, it's all about emissions. you could try to cap that connection to see if it clears. also, most emissions codes won't auto-clear right away, they usually take a diagnostic testing cycle to make it a "pending" code, and another to clear it. a code reader can clear it right away.

have you had the compression tested at another shop yet? you could get a test rig from harbor freight and do it yourself.