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Author Topic: '07 problems/questions  (Read 504 times)

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07inNE

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'07 problems/questions
« on: April 7, 2018, 22:40:54 PM »

Got an '07 LTZ, LC9 engine.  Except for the engine (and related) problems, I love the truck.  Beyond the shadow of doubt it is the most comfortable truck I've ever driven or slept in.  That's good, makes it more comfortable when the truck isn't running and you are stuck on the side of the road. 

Right now, I'm pondering if there is a way (other than getting rid of it) to make the problems go away.  Most of the problems focus around the engine, and most of them seem due to the AFM and electronics.  Time for a new engine, but I can't see replacing the LC9 with another LC9, or indeed, anything with AFM or flex-fuel. 

So what are my options?  What will it take to replace the engine with probably an earlier engine--cast iron block, no AFM, no flex-fuel?  Is there an engine like that that the ECM can be programmed to work with? 
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ygmn

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Re: '07 problems/questions
« Reply #1 on: April 8, 2018, 04:23:51 AM »

Turn off the AFM with hand held programmer and rebuild existing engine.
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07inNE

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Re: '07 problems/questions
« Reply #2 on: April 8, 2018, 06:01:15 AM »

I suspect the engine is too far gone to be rebuilt for a reasonable amount of money, and that would still leave me with the problems caused by the flex-fuel system.  If I'm going to have to replace the engine, I'm going to get rid of both.  I"m trying to determine if there is a way to do that, or if I should just have the thing towed to the scrap yard . . . yeah, that's how frustrated I am, and how tired I am of constant mechanical problems. 
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ygmn

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Re: '07 problems/questions
« Reply #3 on: April 8, 2018, 06:22:25 AM »

There is a kit someone sells to replace the AFM lifters for normal ones and it gets rid of AFM.

Or exchange motor for a JASPER etc...

find a good local mechanic and discuss options
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Vaeagleav

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Re: '07 problems/questions
« Reply #4 on: April 8, 2018, 08:20:57 AM »

I can understand the frustration of having an unreliable vehicle. I agree with ygmn about turning off the AFM with a tuner and getting the existing motor rebuilt since that is the most economical way to solve your problem assuming your first post is correct in that you love the rest of the AV and overall it's in great shape. Any 11 to 12 year old vehicle is going to show it's age and will need maintenance to keep it on the road for another 11 years.....
I don't know exactly what problems with Flex Fuel you are having? I don't think I have read of any problems per say related to the Flex Fuel system and owners replacing or eliminating it. I have read of owners without it putting in ethanol in an older vehicle and having issues.
Maybe you need a better repair shop to properly diagnose and repair your AV?
Also have you owned the AV since 2007 or did you buy it used and possibly have unknown damage, mods or flooding? Sometimes lots of things like aftermarket alarms, remote start or head units can cause problems.
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07inNE

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Re: '07 problems/questions
« Reply #5 on: May 6, 2018, 19:01:29 PM »

Sorry for the delay getting back, work and funerals got in the way.  It did give me time to have the truck towed in to the dealer again for some diagnostics, then towed home after. 

Third owner.  No mods.  No flooding.  Talked with both previous owners, and the dealership that did most of the repairs and maintenance.  First owner said he got rid of it after the engine headaches (he said the engine was replaced, couldn't remember if it was under the warranty or just after that expired) and problems with the fuel system.  Second owner had it for about 5k and reported no problems.

Been to the dealer 7 times (well, 3x to one dealer, 4 times to another) on the fuel problem.  Basically the sensor/computer doesn't correctly read the alcohol content of the fuel.  The dealer resets it, it resets itself.  Right now the computer thinks it is running on 80% alcohol; a bunch of components were replaced, the tank was flushed (again), and the truck filled with straight gasoline about 200 miles before it died last time.  So far on this tank of fuel, I've averaged just over 8 mpg.  When the flex-fuel system decides to behave, I get about 17 mpg. 

As for the engine, one dealer said to buy a new truck.  The service writer at the other suggested repairs to the tune of $4k, then looked at the service records and rather sheepishly said "oops" as it has had all of his recommended repairs and upgrades.  His next suggestion was to replace the engine with a shiny new LC9.  I might have considered it if he hadn't added, "most of the problems are fixed now". 

The independent mechanics I've dealt with the most used to run a shop for one of the area dealers (before that dealer got shut down in the Government Motors fiasco).  He did some diagnostics but refused to try to fix it because he doesn't feel he can guarantee his work on an LC9, and thinks the engine is to far gone to be re-buildable for less than the cost of a different engine.  (First time I've ever stood there with cash in hand and had a mechanic tell me that.)  Back when I first started having problems with it in December '16, he suggested replacing the engine with something other than an LC9 and getting rid of the flex-fuel system, but admitted he didn't know if it could be done.  He thought maybe someone in the Chevy Avalanche Fan Club might know, gave me a flyer he had sitting on his desk, and suggested joining to find out. 

I've talked with 4 other independent mechanics who were willing to work on it (most of the other mechanics I know specialize in older vehicles).  Two suggested junking it, one said the only way he'd work on it was if I wanted to convert to diesel, and one suggested driving it into a bridge embankment. 

I don't want a diesel, and of course I won't drive it into a bridge embankment: it isn't running.  If it isn't possible to fix the problems, I'll part it out or scrap it.  After almost a year of dealing with it, I just want to make sure I've considered every reasonable possibility. 
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ygmn

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Re: '07 problems/questions
« Reply #6 on: May 7, 2018, 05:31:01 AM »

Safe option:
Replace engine with new.
Perform AFM delete kit (new cam and lifters) & Programmer to remove it from computer

Enjoy for many many miles.

Now I am unsure this fuel issue you speak of about Ethanol sensor as that is a first read on here I think.
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bpdutton

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Re: '07 problems/questions
« Reply #7 on: May 7, 2018, 12:00:08 PM »

I have an '07 LT Z71 5.3 and am wondering what type of problems you are having that you think are attributable to the AFM?  Also, how do you know if it's an "LC9" engine and is that the only one with AFM problems?  Newbie here so trying to understand.
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'07 LT Z71

07inNE

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Re: '07 problems/questions
« Reply #8 on: May 7, 2018, 21:34:23 PM »

Safe option:
Replace engine with new.
Perform AFM delete kit (new cam and lifters) & Programmer to remove it from computer

Enjoy for many many miles.

Now I am unsure this fuel issue you speak of about Ethanol sensor as that is a first read on here I think.
Rather than replacing the engine with a new engine, then basically having to replace the (new) cam and (new) lifters and (new) oil pump, then program the AFM system out, I'd prefer to have an engine that is designed from the get-go without the AFM.  If GM could show a run of say 4-5 years with an LC9 without problems, I'd reconsider that position.  At this point, putting more money into an engine design that has previously failed twice seems. . . well, foolish.  I'm just trying to figure if there is a way to do it. 

As for the fuel system problem, take a look at this thread (among others) http://www.chevyavalanchefanclub.com/cafcna/index.php?topic=119634.msg1841285#msg1841285  Software mods haven't fixed it, various repairs by the dealers haven't fixed it. 

BPDutton, I think all of the '07 Avalanches (and other vehicles) with the 5.3 had AFM and associated problems, not sure about that though.  You can run your VIN on one of the on-line VIN decoders, or have your dealer run it, to determine which engine etc you have.  Or you can take your title in to a parts dealer and have them run it to determine the engine.  Check plugs 1 and 7 for excessive fouling, monitor your oil consumption, watch for black smoke from your tailpipe.

Searching here in the engine forum can turn up a lot of threads dealing with the problems and various attempted fixes by GM. 
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gmantwo

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Re: '07 problems/questions
« Reply #9 on: February 8, 2019, 17:51:02 PM »

I have an ‘07 with 197,000 miles on it and none of the problems you’re having. Flexfuel truck too
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