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post #1 of 6 Old 01-17-2013, 05:44 AM Thread Starter
mj86
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1986 MJ Comanche 
 
Join Date: May 2012
Location: Flint
Posts: 17
back fire

I've changed distributer, plugs, wires, air filter, oil change, tune up. Still getting back fire, any ideas.
Thanks for any help
Mj86

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post #2 of 6 Old 01-17-2013, 03:16 PM
mj40
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1989 MJ Comanche 
 
Join Date: Jul 2011
Location: north bay/corbeil
Posts: 282
double check the firing order- no spec's on the truck???...so i cant give you this info- other than look at the intake for the firing order-4cyl 1342...6cyl-2.8l chev 123456 135 passangerside 246 driverside- make sure to start the wires on #1

check the timing??
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post #3 of 6 Old 01-17-2013, 05:40 PM Thread Starter
mj86
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1986 MJ Comanche 
 
Join Date: May 2012
Location: Flint
Posts: 17
fire order

It has a 2.5L. There is no rime or reason, it does it when it is hot and cold. Sometimes real loud and sometimes soft and sometimes it doesn't do it at all. So confused.

MJ86
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post #4 of 6 Old 01-17-2013, 05:43 PM Thread Starter
mj86
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1986 MJ Comanche 
 
Join Date: May 2012
Location: Flint
Posts: 17
MJ40, thanks for your help. I'm a true beginner when come to working on vehicles.
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post #5 of 6 Old 01-17-2013, 06:14 PM
mj40
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1989 MJ Comanche 
 
Join Date: Jul 2011
Location: north bay/corbeil
Posts: 282
need to know is it backfiring through the exhaust or the intake?
how does it idle/rpm? rough may have a bad intake or throttle body gasket
this link may help just to verify the base timing is ok...
http://www.4wdmechanix.com/Tuning-an...-TBI-Four.html
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post #6 of 6 Old 01-22-2013, 04:29 AM
cruiser54
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1990 MJ Comanche 
 
Join Date: Oct 2009
Location: Prescott
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There are some vacuum lines just below the throttle body that crack and rot. Also, remove the ground strap from the firewall, scrape the paint off, shine up the connector, and reinstall securely.

If you own a Renix Jeep, you'll want to check this out.

An index to over 30 write-ups can be found in the link below

www.cruiser54.com

My Jeep Technical Photos

http://www.cherokeeforum.com/g/album/1725214
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