only firing on cylinder 1 2 and 3
#1
Thread Starter
Junior Member
Joined: May 2010
Posts: 53
Likes: 0
From: michigan
Year: 99
Model: Cherokee
Engine: 4.0
only firing on cylinder 1 2 and 3
i was picking up a buddy and while i was waiting my jeeep started to run like **** i was able to limp it home but trying to figure out what was wrong with it i found that i was only run on the front 3 cylinder when i puller the plugs the front 3 were black and the back 3 were white and wet i have tryed just about everything cant figure it out
any one got any ideas????
any one got any ideas????
#4
Let's slow down and troubleshoot instead of shotgunning it. It is a strange symptom, indeed, but you still need to approach it systematically.
First step: are you missing spark or fuel on cyls 4-6? Have you tested compression?
First step: are you missing spark or fuel on cyls 4-6? Have you tested compression?
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#9
Caracticus Potts The Mod
Joined: Jul 2009
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From: Hainsville, NJ
Model: Grand Cherokee
#10
::CF Moderator::
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From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
#11
CF Veteran
Joined: Aug 2010
Posts: 8,357
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From: Canton, MI
Year: 1999
Model: Cherokee
Engine: 4.0
#12
Thread Starter
Junior Member
Joined: May 2010
Posts: 53
Likes: 0
From: michigan
Year: 99
Model: Cherokee
Engine: 4.0
its a he and that ones of my other ones lol and the one i am haveing issues with is a 98 classic with the 4.0l and my buddys got the same one so we have been swapping parts to see if thats the issue
#14
CF Veteran
Joined: Aug 2010
Posts: 8,357
Likes: 90
From: Canton, MI
Year: 1999
Model: Cherokee
Engine: 4.0
Geeez, that motor sounds like a jewel.
Check to see if there's a piston in #6.
Remove the fuel pump relay, disconnect the coil primary connector, remove #6 sparkplug, Have someone crank the engine over while you hold your finger over #6 spark plug hole. See if you get any pressure to build up whatsoever (is that a word?).
Replace the spark plug, leave the relay out and coil disconnected. Remove the TB intake tube. Hold the throttle plate open and have someone crank the engine, listen for air escaping through the TB. If it does, the intake valve has a problem. If not go to the tail pipe and listen there while it's being cranked. Same story, if you can hear air escaping through the tail pipe it's a bad exhaust valve. If okay, listen at the oil filler on the valve cover and/or oil dipstick tube (with a length of hose at the opening). Air escaping would indicate a bad piston or rings are laying in the oil pan.
Option would be to do a compression loss test on #6 using 90 psi air and do the listening things. Edit: And do a compression loss check on #5 with #6 plug removed and see if the pressure in 5 bleeds accross to 6.
Check to see if there's a piston in #6.
Remove the fuel pump relay, disconnect the coil primary connector, remove #6 sparkplug, Have someone crank the engine over while you hold your finger over #6 spark plug hole. See if you get any pressure to build up whatsoever (is that a word?).
Replace the spark plug, leave the relay out and coil disconnected. Remove the TB intake tube. Hold the throttle plate open and have someone crank the engine, listen for air escaping through the TB. If it does, the intake valve has a problem. If not go to the tail pipe and listen there while it's being cranked. Same story, if you can hear air escaping through the tail pipe it's a bad exhaust valve. If okay, listen at the oil filler on the valve cover and/or oil dipstick tube (with a length of hose at the opening). Air escaping would indicate a bad piston or rings are laying in the oil pan.
Option would be to do a compression loss test on #6 using 90 psi air and do the listening things. Edit: And do a compression loss check on #5 with #6 plug removed and see if the pressure in 5 bleeds accross to 6.
Last edited by CCKen; 01-27-2013 at 01:05 PM.
#15
Thread Starter
Junior Member
Joined: May 2010
Posts: 53
Likes: 0
From: michigan
Year: 99
Model: Cherokee
Engine: 4.0
ok ill try that stuff but that dosent solve the issues of not firing on 4 -6 i can seeing bleeding from 5 to 6 but where would the cylinder 4 come into play?