08 Hybrid Tahoe - Multiple little issues

tiktok4321

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I've experienced the same sort of jerk/shudder as others have mentioned. Took to a Hybrid tech who said all the codes look fine and that the battery pack looks good. 12v also checks good. I'm now almost not getting any hybrid mode, and when I do, its for short bursts. MPG dropped from 19 to 17.9. Since clearing all codes, nothing new has shown up except a cylinder 8 misfire. Could that disrupt the Hybrid system without faulting it?

In other questions, more and more lately, the display of my info system stays off longer and longer, then randomly pops up. If I had the radio on, it still plays the radio. Power and volume work fine. Any ideas?
 

zora

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You state you cleared all the codes yet make no mention of what they are other than a #8 misfire which could be the source of all your problems. Why didnt the tech pursue what the cause of the #8 misfire was?
 

tiktok4321

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There was one about the a/c compressor, and the rest were what he just described as years of minor junk codes. Because the car sat at Auction and at a Dealer for an unknown amount of time, he wanted to reset all the codes, and if the problem persisted, see what comes up.

P0308 is the only code that's come up since the reset.

ONCE, I got the dreaded P0AC4 and P061B codes regarding the hybrid system, but they cleared themselves.

I doubt the stereo head unit is hybrid specific. Maybe it is because there is a hybrid tab on the menu. Are there any known issues about those units?
 
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tiktok4321

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It's worth following up in case anyone comes here looking for answers. The P0308 was a Cylinder #8 misfire. The culprit was a stuck hydraulic lifter. Dealer and other mechanics wanted to replace the whole engine for between $5-9K! Their excuse? Bet the lifter wore down the cam lobe. Got another guy to look at it and he replaced all the lifters, head gaskets and seals for $1600. He did admit, though, that he "underbid" the project. That code has been clear since April '17.

Now the other issue I was having. The dreaded P0AC4 and P061B. These codes pop up whenever the engine dies when transitioning from resting at a light in AutoStop and then accelerating, transitioning from AutoStop to engine start. That ain't cool right there. I'll skip past all the troubleshooting and just say this: Everyone agreed that the Hybrid battery pack was fine. Though, a thorough cleaning of the pack (especially around the fan) yielded an MPG improvement from around 16.4 to around 19.2. The ultimate culprit? A loose 12V terminal harness. They tightened that thing right up and I haven't seen those codes since, even with a 5 year old 12V battery!

Things aren't 100% perfect yet. I'm still trying to get the 'Hoe to spend more time in Autostop, and try to get it up to 20 mph for a few seconds before switching over. But for now, I'm happy that I'm not stalling the car with people honking behind me at an intersection.
 

zora

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thanks for the update on your issues. Any idea if the loose terminal harness was due to someone working on it and not tightening it or just age?
 

tiktok4321

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A little of both. Initially, I think it was age. When the guy cleaned my Hybrid battery pack, he disconnected the 12V. Apparently, he put it on loose, and my symptoms got worse until it was properly tightened, and the issue hasn't recurred since.
 
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