Backfires when slightly touch throttle
01-12-2010, 09:30 PM
#1
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Model: Cherokee
Backfires when slightly touch throttle
Hi my name is David I have been looking through this forum for some time now. It has a lot of great info. I am new to using forums. any way to my question I have a 90 xj 4.0l that i got dirt cheap (now i know why) It will idle fine but when you slightly touch the throttle it back fires threw the exhaust give more throttle it backfires threw intake. I have changed and checked:
timing ( not sure what it should be its about 12 at idle jumps when gas applied)
plugs, cap, rotor
distibutor (distributor is at #1 tdc comp stroke)
module
tps (replaced with used one checked voltage good now)
cps
computer (replaced with used one)
found low vacuum 8lb at idle 0 when gas applied ( should be higher)
intake/exhaust (found a leak around #6 after replacement vacuum still same even with all ports pluged can not find a leak now)
compression is around 120 in all cylinders.
map sensor (used one)
checked all grounds that i know of
this is what I know about this jeep. the motor is out of a 90 xj 4 door auto and is now in a 88 xj 2 door man i do have both xjs wire harness from 90 was used ( also have an 85 xj it wants a v8
)
any help would be great if I had much hair I would pull it out
Thank you for the help
timing ( not sure what it should be its about 12 at idle jumps when gas applied)
plugs, cap, rotor
distibutor (distributor is at #1 tdc comp stroke)
module
tps (replaced with used one checked voltage good now)
cps
computer (replaced with used one)
found low vacuum 8lb at idle 0 when gas applied ( should be higher)
intake/exhaust (found a leak around #6 after replacement vacuum still same even with all ports pluged can not find a leak now)
compression is around 120 in all cylinders.
map sensor (used one)
checked all grounds that i know of
this is what I know about this jeep. the motor is out of a 90 xj 4 door auto and is now in a 88 xj 2 door man i do have both xjs wire harness from 90 was used ( also have an 85 xj it wants a v8
)any help would be great if I had much hair I would pull it out
Thank you for the help
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01-12-2010, 09:51 PM
#9
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I will change them and see if that helps so far everything i have done no charge at all oh when it is cold it idles rough but when it warms a little smoothes out
i did check egr also
i did check egr also
01-12-2010, 09:54 PM
#10
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Year: 1987
Model: Cherokee
Engine: 242 inline six
when I did my wifes car it was like that,changed everything I could think of,ended up being just the dam plug wires.Thats my 2cents.
01-12-2010, 09:54 PM
#11
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i read a post on here I think it was titled timing what else could it be it sounded alot like my problem but there was no end results
01-12-2010, 10:04 PM
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My first thought was timing tried to turn dist. but no luck then saw the ears on it I felt dumb
Do you know what the timing should be at when you put a light on it
Do you know what the timing should be at when you put a light on it
