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98 Tahoe misfire


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Join Date: Dec 2009
Posts: 1,854
kentucky

December 12th, 2009, 12:57 PM   #1  
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98 Tahoe misfire

98 tahoe, 5.7/auto trans. 162k miles. Changed plugs, fuel filter, air filter, fuel pump/sending unit assembly. When I changed the plugs, #3 and #5 both had ash like deposits, I've read that this could have been caused by additives. Truck runs great with the exception of a low rpm, under load stutter. At highway speeds it will stutter and miss really bad if I'm going uphill in overdrive. Usually happens around 1600 rpm's. It will not do it accelerating from a stop, only at highway speed, only under 2000 rpm. If I use 3rd gear uphill, it runs great, no issues. I do get a #5 misfire on code reader, which sometimes corrects itself, sometimes doesn't. I can't see any coolant loss, oil consumption is virtually non existant. I've heard it could be intake leak, egr, ignition. Any Chevy guys have this problem? Any ideas?

 
Join Date: Sep 2009
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hutchinson mn

December 12th, 2009, 1:45 PM   #2  
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My 98 silvy did that to and I did the same things you know change plugs and all, checked conections and went through it top to bottom. I came up with nothing other than my distributer one of the tabs that holds it on was cracked off but that wasnt the prob so I gave in and took it to the shop and told them and the found that the previous owner didnt do the intake gaskets right. they put he distributer in wrong. it was 13 degrees retarded and the crank sensor and cam sensor were not synced up.

 
Join Date: Dec 2009
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kentucky

December 12th, 2009, 2:00 PM   #3  
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Thanks. I'll try to take a look at distributor. Not sure if intake gaskets were ever replaced, or what may have been messed with.

 
Join Date: Sep 2009
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hutchinson mn

December 12th, 2009, 4:30 PM   #4  
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Sounds good at least look into that because its not the leading casue for these problems but it useally comes out to be something of that sort and dont give up, my truck was a turd before and was close to selling it and know I can hardly keep from just wanting to drive it.

 
Join Date: Dec 2009
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kentucky

December 13th, 2009, 1:06 PM   #5  
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That's what puzzles me a bit. the truck isn't slow at all, or lacking power. I step on it, she goes. It's only at freeway speed when i lightly accelerate that she starts jerking and shuddering. Otherwise, she runs great.

 
Join Date: Jan 2009
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December 14th, 2009, 5:50 PM   #6  
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Hi everybody just i finished installing my navigator and my folding mirrors in my suburban 07 it was fun it took a few months but i did everything snd the results were perfect i love it i really love it. I want to share the way i installed it and dont listen to those stupid dealers that say that you can not install navigators and folding mirrors if your saburban is not built for that. I spent $1200 and i bought everything on ebay. later on i will give you some pics oin how to install it. See you all soon.

 
Join Date: Mar 2010
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Bartlett, TN

March 1st, 2010, 5:22 PM   #7  
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What was your fix? My 1999 is doing the same thing.

 
Join Date: Dec 2009
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kentucky

March 1st, 2010, 6:08 PM   #8  
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still a work in progress hunt. it may be due to low compression in one cylinder. soon as i can get everything fixed and runnin at tops, i'll let ya know

 
Join Date: Mar 2010
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Bartlett, TN

March 2nd, 2010, 7:27 AM   #9  
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I have replaced TPS, VSS, MAP, and upgraded spider. Mine starts as low as 35 mph after the TCC locks up and then quits above 55 on light throttle. It does not do it at all with above 30 percent throttle. I drove the Tahoe over 100 miles with a misfire on 4 and 8 replacing the rotor and cap fixed that. I think my camshaft retard sensor is bad. I also think it may be my ignition control module.

 
Join Date: Dec 2009
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kentucky

March 2nd, 2010, 9:54 AM   #10  
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i would run a dry and a wet compression test. this is how i found my problem. cyl 3 was 30 psi lower than all the rest, so now i'm in process of fixing this. also, check, or have checked, the fuel pressure.

 
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