wheelin today and a couple of issues

[f5fstop]

Originally Posted by timgco

stock air filter. The only mods done to engine would be the cat back B&B Exhaust. This truck has also had a trans replaced. I'm not sure on the air filter hose/ intake being kinked or blocked. I honestly have neverr had the aibox open yet.

They arer still blaiming the exhuast.

Have them give a definite reason why the exhaust would cause this problem. Dealers are notorious at blaming something on an aftermarket item, with no proof or experience when they fail to find the true problem. They may not be able to find the real problem, not due to their incompetence, but due to the fact that once in a while these new vehicles will exhibit a behavior that can't be explained.

I will check today, in case I'm wrong, but I have never in my life heard of a cat-back exhaust causing any problems with the engine or trans, and even early in the AM, I cannot conceive of what the exhaust would do to cause the problems you stated. If the exhaust was clogged, yes, but if it was clogged, it would not run ok afterward either. And what normally clogs exhaust systems, catalyst material discharged from the catalyst due to backfires. This you don't have, so I rule out the exhaust.

The exhaust is a static device, if it was causing problems, it would cause problems all the time at high altitudes, a restart would not fix the problem. (Just my opinion.)

I'm still thinking the PCM or a sensor "farted" and the restarts fixed the problem, similar to my 4-wheel drive problems on the trip. The trans bulletin is just a "maybe" since it does show some of you symptoms. Problem is you have those other codes too.

[h2co-pilot]

F5 is a such a Sweetheart - always helping out.

Hope you get it straight Tim.

[Ipedog]

All hail F5

[f5fstop]

You have an interesting PM that includes some information .
Again, if you want to show them the write up to the dealer, feel free, just remove any identification of who sent it.

[timgco]

Originally Posted by f5fstop

You have an interesting PM that includes some information .
Again, if you want to show them the write up to the dealer, feel free, just remove any identification of who sent it.

Thank you. I just called the service dept. They drove it last night and couldn't duplicate the problem. no $hit!

So I told him word for word what "my source" had said. I also answered one of the two questions. Reduced engine powere was present until the egine was turned on and off. I'm getting you the other info as well.
Thank you.

[f5fstop]

Just had a another reply from powertrain programming engineer, and she states the P0121 is the code to go after.
When the PCM detects a condition within the throttle actuator control (TAC) system, other DTCs may set due to the many redundant tests run continuously on this system. Locating and repairing one individual condition may correct more than one DTC. Keep this in mind when reviewing captured DTC info.

She is also leaning toward a TP sensor, but could be a MAP sensor. She also states that it could have been what I suggested, "a brain fart," that may never happen again. Just a scenario where the inputs got slightly messed up for a second or two, and the PCM could not relate all the inputs. Restarting the engine cycled all back to normal, and the PCM shook it off and went back to normal mode.

[Wisha Haddan H3]

Originally Posted by timgco

Thank you. I just called the service dept. They drove it last night and couldn't duplicate the problem. no $hit!

So I told him word for word what "my source" had said. I also answered one of the two questions. Reduced engine powere was present until the egine was turned on and off. I'm getting you the other info as well.
Thank you.

Where did you take it to? I want to know if I should avoid the Medved (Wheatridge) service dept the way I avoid their sales dept.

[usetosellhummer]

ddaammmnnnn you man f5, I vote you as a Hummer god.

[f5fstop]

New information. The way John phrased it is it could be a brain fart that could become a stroke. He is thinking there computer program, for some reason, could have become confused by certain inputs, and one of those inputs may have failed temporarily, and could fail totally later.
He is the first person who I have talked to made a statement about the exhaust. The engine parameters are looking for a specific back pressure; usually a small amount of change makes no difference. But, at this altitude, and you possibly doing something normal but strange to a sensor (such as momentarily lifting off the accelerator, then flooring it, or just the opposite),the computer reacted with a reduced power mode. Resetting it by turning it off/on made it reboot, similar to a Windows Brain Fart.
Just another opinion. But he wants to know the final conclusion if there is one.
First guy is still waiting for any information he can get. He is also very curious.

[timgco]

F5- i want to thank you for your efforts on this!!!!!!!!!!!!!!!!!!

You are a huge asset to this forum.

The dealer is reaplacing the TPS due to the "higher up" recomendation.

I smiply stated that this came from someone on a design/ engineering team for these truck and names/ positions were withheld.

After i told them of my connections, they did not hesitate to take the advice and run with it. So we'll see.

I fully plan on running McCalister's gulch this weekend on Sunday and will see what happens @13,000ft.

Thanks again for your help!!!!!!!
Tim.

[f5fstop]

I really hope that it was the problem. Everything seemed to lean that way, but it was just some educated guesses from miles away.
Glad to be of some help and good luck running the pass.