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1999 Tahoe shuts off on and on while driving


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#1 typicalsituations

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Posted 17 June 2006 - 08:50 AM

1999 Tahoe OBS
5.7 Vortech
Bone Stock

I have read and read and read and no one seems to have had this problem. I think it all started about 6 months ago when I paid a friend to change my intake manifold gaskets. He removed the distributor and did not mark it. When I got it back it ran great but I had the OBD code that said the dist. was off by more than a degree. He didn't have a scan tool at his shop that could read this spec. I've been driving with it like that since. No drivability issues, nothing.

So back in May I drive to work and everything is normal. When I go to leave I get on the highway and BAM. It felt like someone rear ended me slightly over and over. No this is not the drivetrain clunk that I've been living with for years, this is BAD. Just the night before I'm sure that I got bad gasoline from RaceWay.... So I looked to the fuel system.

It happens over and over, almost like the truck is just cuting itself off randomly. I got back to work and tried it again later, it cut off and I had to pull it home.

NO CODES show up except the one that was there before, for moment I had P0339. Which is the cam shaft sensor... I started out by changing that. Nothing... I was able to get it to run, but it would shut off.

I changed the Fuel pump, Filter, Mass Airflow Sensor, both upstream O2 sensors and plugs. It would start but IDLE rough.

So I work on it and it seems to run better everytime I crank it.
I heard the Idle control valve making funny sounds so I disocnnected it and plugged it back in. It ran like a top after that with a slight rough idle.

So I drive it around for a month and I notice that it kind of did the same thing it was doing a month before but just once and ever so slightly. The next few days it get worse....

This morning I leave my drive way... and BAM... worse than before.... Like the engine is cutting itself off RPM's jumping ALL OVER the place, 0 to 1500 700 500 200. The gauges going nuts.... I've checked all electrical possibilities... everything is fine.... It left me in the middle of the road and kept cutting off while going down the road...

My conclusion... I have no idea. Maybe the distibutor being off for a while caused problem? It idles fine when its not in gear, its hard to crank, sound like a weak battery, but its not.

I don't even want to think about the tranny... My rear differential has a slight gasket leak.

PLease comment on posible solutions... I have to find a ride to work! :P

Thanks. :cheers:

Ron

#2 rjirvine

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Posted 17 June 2006 - 09:41 AM

According to my book, P0339 is an intermittent crankshaft position sensor (CKP)circuit, not the camshaft position sensor (CMP) as you stated. Did you inadvertantly get them confused?

#3 typicalsituations

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Posted 17 June 2006 - 10:40 AM

Perhaps. That code doesn't pop until you try to drive it a while while its cutting off. I assume its a direct result of the "main" problem. Also, the fact that it happend the first time out of nowhere, after it had been running fine, further confirms my theory. I may be wrong, but thats just my gut feeling. While its running harshly the engine knocks if you gas it... It a unique problem I've having and I'm scared to take it to the Dealer. I don't know any reputable shops here in South GA. I can handle most projects with the Tahoe, this is the type of problem I can't handle without proper scan tools.

#4 typicalsituations

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Posted 17 June 2006 - 10:47 AM

oh, the code I had previously after the distibutor was taken out and back in is p1345. I don't think it would cause THIS big of a problem, but I don't know. I know its a 30 min job to hook up the Tech 2 and get it to the right degrees.

#5 rjirvine

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Posted 17 June 2006 - 12:32 PM

Hmm, I would check the connection on the Crank sensor and make sure it's fully seated, and then get the distributor timing straightened out. I'm thinking that should take care of your issues. I would also make sure the connection on the hall effect sensor is ok on your distributor. I had one go bad on the wife's car and it would kill the engine an the most inopportune times.

#6 typicalsituations

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Posted 17 June 2006 - 03:17 PM

I think I might have found something I overlooked before. I just found a wire harness going to the Crankshaft sensor and some other sensors (coolant).. and it wastouching my exaust manifold. Needless to say the loom was burned and one of the small wires in there was completley exposed and probly hitting the manifold. This is probly what is wrong, if not, its definatly something to fix. Can't find the electrical tape though.....

#7 Corky356

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Posted 17 June 2006 - 08:50 PM

I think I might have found something I overlooked before. I just found a wire harness going to the Crankshaft sensor and some other sensors (coolant).. and it wastouching my exaust manifold.  Needless to say the loom was burned and one of the small wires in there was completley exposed and probly hitting the manifold.  This is probly what is wrong, if not, its definatly something to fix.  Can't find the electrical tape though.....

<{POST_SNAPBACK}>


That's more thanlikely the problem, but don't just ignore the timing.

#8 rjirvine

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Posted 18 June 2006 - 08:09 AM

Take a good look at the exposed wire. If it has been bare for sometime, it can be corroded between the individual strands (and/or some strands may be broken) and still make a bad connection. Depending on the damage, you may have to cut out the bad area and either splice it back together, or better yet solder a new connection. Use some heat shrink over the connection if you have some. I hope you've fixed your problem. Let us know!

PS As the earlier posters stated, I'd agree that you should still get the timing fixed too.

#9 typicalsituations

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Posted 20 June 2006 - 07:47 AM

I'm pretty sure that was the problem. One wire was missing 3/4 of an inch of insulation and two other wires insulation had each a small crack. For now I taped them all back up. I may end up trying to find that harness at a junk yard.

As for the timing, of course the dealer did not have time for me yesterday so I must drive it like that for another week.

Could I be doing some major damge with the timing off like that? Man what happend to the days of the timing light and a little patience?




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