2006 Tahoe Engine stumbles/dies when I hit a bump

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J West

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I have a 2006 Tahoe 4WD 5.3V8 with 170k miles on it. New transmission at 110k.
It has been a great vehicle, but a couple of years ago it developed an issue where it would die when I hit a hard bump. It did this for quite a while but I was able to live with it since it only happened on off road conditions. As time went on, however it got worse until it would die even hitting seams in bridges. It just dies but you don't even notice until you hit the gas and nothing happens. No dash lights, no indication. Just going down the freeway at 75, cross a bridge and the engine isn't running anymore. Put it in neutral, crank it and it starts right back up on the fly, back into drive and I keep going! Needless to say my wife does not appreciate this feature!
It also developed a condition that it almost always takes two attempts to start. It used to start immediately when you turn the key, but now it will crank and then stop, and then start immediately when I turn the key again.
So I broke down and dug into it. It never lit the check engine light, but it did generate codes for camshaft sensor signal high and low P0342,343 (which is contradictory).
I checked all of the wiring possible. Added additional ground wires between the engine, battery and frame. Did everything I could find online as a possible remedy.
I replaced the camshaft sensor and checked all the wiring to it. No change. ($60)
I had the fuel pump replaced, no change ($200)
Took it the dealer, they put it on their computer and drove it for two days and then gave it back and said it was misbehaving but they could not find anything wrong ($100 later).
I called a local mechanic who claims to be the Chevy expert and he said I already did everything he would try, so I should put on a helmet and crash it into a wall and collect the insurance, but otherwise had no suggestions.
As a last hope I replaced the camshaft sensor and the ECM. ($200) This stopped it from dying under normal driving conditions, but it still dies on really rough roads. It still sometimes stumbles when I hit a bump like a bridge seam and the tach briefly drops near zero and then pops right back up, but it does not die (yet). It also still takes two tries to start.
So I'm just fishing for anyone who has experience or suggestions before I take the mechanics advise or trade it in for something that works. It's a great vehicle and I'd hate to give up on it, but it's not reliable and I can't trust it so something has to give.
Thanks!
 

wjburken

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I would be checking all ground wire connections. Also check your battery cables, positive and negative, for corrosion along the length of the cable.
 

OR VietVet

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First: Welcome to the forum from Oregon.

Second: I never would have guessed the fuel pump because when you have problems with a fuel pump it either has a loss of power or it will sputter/stumble before engine dies.

Third: I would have guessed the cam and crank sensors too and hope you used GM replacement parts. I believe it is something to do with the ignition switch or wiring for it.

https://www.rockauto.com/en/moreinfo.php?pk=192838&cc=1434093&jsn=947

Fourth: The rest is purely guess work and maybe should get that helmet ready or just trade it in and don't allow a road test by the buyer any farther than 50 feet driving on finished concrete.
 

Danny3737

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I know this sounds like a long shot, but a couple of decades ago a friend of mine had a similar experience on a different type vehicle. His problem was because the weight of his key chain. Apparently the weight of the key chain caused excess wear on the cylinder and it slowly over time got worse. We only discovered that was the problem for everything when the key cylinder failed completely. Once we replaced it, all the other issues went away. We spent countless hours tracing wires, grounds, etc. Electrical issues are the hardest and most frustrating to diagnose. I’m only guessing it’s electrical, just a hunch.
 

Mudsport96

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Well if a jolt on the road is enough, just let it idle while you go around tapping on components and the wiring harness. Eventually you will wiggle whatever the bumps do and it will stall.
 
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J West

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Well if a jolt on the road is enough, just let it idle while you go around tapping on components and the wiring harness. Eventually you will wiggle whatever the bumps do and it will stall.
Thanks for the reply. I have literally put it up on ramps and smacked everything I can with a heavy rubber mallet. I have taken a broom handle and pushed and prodded every wire I can reach under the hood and under the dash. I cannot get it to fail in any way with it stationary.
 
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J West

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I know this sounds like a long shot, but a couple of decades ago a friend of mine had a similar experience on a different type vehicle. His problem was because the weight of his key chain. Apparently the weight of the key chain caused excess wear on the cylinder and it slowly over time got worse. We only discovered that was the problem for everything when the key cylinder failed completely. Once we replaced it, all the other issues went away. We spent countless hours tracing wires, grounds, etc. Electrical issues are the hardest and most frustrating to diagnose. I’m only guessing it’s electrical, just a hunch.
Thanks. I'm guessing its electrical, and I have heard of the heavy key-chain problem. When I ask the dealer mechanic about that he said if the ignition switch was bad, it would light up the dash lights when it turned off. I have rattled and hammered the ignition switch and all of the wires in the steering column with it running and cannot get it to fail by doing so.
 
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J West

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BTW-Welcome to the forum from Iowa.
Thanks!
I would be checking all ground wire connections. Also check your battery cables, positive and negative, for corrosion along the length of the cable.
Thanks for the reply. I removed, cleaned reconnected the battery cables at both ends. I also ran a ground strap from the battery to the engine block and then to the frame just to make sure ground connections were not to blame. The is a ground wire from the back of the engine to the firewall that reportedly causes trouble but I checked it and it is ok. But without any success.
 
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J West

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First: Welcome to the forum from Oregon.

Second: I never would have guessed the fuel pump because when you have problems with a fuel pump it either has a loss of power or it will sputter/stumble before engine dies.

Third: I would have guessed the cam and crank sensors too and hope you used GM replacement parts. I believe it is something to do with the ignition switch or wiring for it.

https://www.rockauto.com/en/moreinfo.php?pk=192838&cc=1434093&jsn=947

Fourth: The rest is purely guess work and maybe should get that helmet ready or just trade it in and don't allow a road test by the buyer any farther than 50 feet driving on finished concrete.
I also guessed the ignition switch, but I can shake and hammer and poke at all of the wires in the steering column and it will not have any effect. I suppose I could replace it just in case...
 

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