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01-02-2012, 09:08 AM | #1 |
Registered User
Join Date: Oct 2011
Location: Fairfax, vermont
Posts: 111
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multi mis fire problem
I have an 05 silverado 2500hd 4wd 6.0 auto. I get a code of a multi misfire in 7+8. What I have done: switched around to other cylinders, wires, plugs, coil packs, and injectors, discounected battery over night. Still showing the same codes. It seeems to level out after 2k rpms. fuel pressure good, no vacume leaks. Been adviced to do a computer upgrade.
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01-02-2012, 09:50 PM | #2 | |
Senior Member
Join Date: May 2009
Location: Fort Worth, TX
Posts: 6,370
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Re: multi mis fire problem
Quote:
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01-03-2012, 06:56 AM | #3 |
Registered User
Join Date: Oct 2011
Location: Fairfax, vermont
Posts: 111
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Re: multi mis fire problem
did that, compression is good. I only checked 7+8 though. 7+8 are at the bottom (gravity) of the fuel rails. could there just be **** in them. I did get a little difference for a little while after I put a new injector in +8. I have been using cleaner every fill up. no progress.
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01-03-2012, 09:42 AM | #4 |
On a budget like Fred Sanford
Join Date: Oct 2005
Location: Topeka, KS
Posts: 2,031
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Re: multi mis fire problem
How many miles? Can you actually feel/hear the misfires or does it run fine? I had very similar symptoms on my '01 5.3 with cyl 1 & 3 and it was a clogged catalytic converter, but my misfires were audible.
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'85 Silverado swb: 383 stroker, 10.5:1, vortec heads, 232/238 roller cam, RPM air gap, performer 750 carb, stainless longtubes, 3" duals/super 44's, T56/4.11 383ci build / exterior refresh thread '98 Camaro z28: 370ci twin turbo 370ci build '01 Tahoe LT 4x4: 5.3, longtubes/ory, magnaflow duals, custom tune....wife's DD |
01-03-2012, 01:11 PM | #5 |
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Join Date: Oct 2011
Location: Fairfax, vermont
Posts: 111
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Re: multi mis fire problem
197,000 (alot) yes, i can feel it at idle. smooths out after 2k rpm. converter replaced about 40k ago
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01-27-2012, 05:44 PM | #6 |
Registered User
Join Date: Oct 2011
Location: Fairfax, vermont
Posts: 111
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Re: multi mis fire problem
problem is getting worse. I was told to take the fuel rails off and give them a good cleaning. do you guys concur
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01-27-2012, 06:53 PM | #7 |
Registered User
Join Date: Nov 2011
Location: Rapid City SD
Posts: 140
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Re: multi mis fire problem
I would check for a vacuum leak at the intake gaskets. They usually show up on the end two cyllinders first.
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1970 : Chevy: K20 "Frank the Tank" 6.0 LS, 4L80E, 14 bolt, and Dana 44 1970 K5 Blazer CST 350, TH350, Np205, Dana 60 and 14 bolt General Motors Master Certified wrench swinger ASE certified Master auto tech Instructor of Automotive Technology |
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