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Random Misfire

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Old 04-26-2012, 10:08 PM
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Default Random Misfire

Sometimes when i start my jeep up it has a bad misfire but i can shut it off and start it right back up and it doesnt have a miss but it struggles to start, ive replaced just about everything i think of that would cause this plugs wires, distributor, crank sensor, external ignition coil, computer, fuel filter, tps throttle body gasket and i drive it around and it seems to be running fine untill i shut it off and turn it back on and has the bad misfire, but i can start it up again it doesnt have the miss,

its a 94 cherokee 4wd 4.0l auto has about 200,000 miles

any help text anytime 7578148258 or email me shadyredline@gmail.com looking to fix this problem and sell it

Last edited by shadyredline; 04-26-2012 at 10:11 PM.
Old 04-26-2012, 10:16 PM
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bad injector or wiring or grounds?
Old 04-27-2012, 08:52 AM
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Originally Posted by TheJerm
bad injector or wiring or grounds?
Or I think a bad head gasket between cylinders as well... Not trying to scare you, just saying...
Old 04-27-2012, 10:52 AM
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This is a known problem with the 4.0s called a "heat soak." Usually it affects newer ones but my 95 does it occasionally. Whenever you kill the engine all the heat from the exhaust manifold will heat up the cylinder 3 injector to the point that it will misfire. It can be resolved by wrapping the injector in insulating tape
Old 04-27-2012, 01:02 PM
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Originally Posted by bighouts5591
This is a known problem with the 4.0s called a "heat soak." Usually it affects newer ones but my 95 does it occasionally. Whenever you kill the engine all the heat from the exhaust manifold will heat up the cylinder 3 injector to the point that it will misfire. It can be resolved by wrapping the injector in insulating tape
X2
Wow 2 years of being on this forum I've never heard it put so well!
Old 04-27-2012, 05:23 PM
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Originally Posted by shadyredline
, ive replaced just about everything i think of that would cause this plugs wires, distributor, crank sensor, external ignition coil, computer, fuel filter, tps throttle body gasket

its a 94 cherokee 4wd 4.0l auto has about 200,000 miles
Does yours have an IAC valve? If so its on the TB. your o2's and heater circuit are suspect, too. You said you replaced the computer- the ECM? Idk the 94's well enough.. Your odb-2, so I guess you have the same kinda ECM I do ('99). Another thought is the clock spring. It allows the steering wheel to rotate and maintain function of the electronics like blinkers, horn and airbag. The clock spring also grounds the TPS.
Old 04-29-2012, 11:41 PM
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maybe its worth taking it to someone who has the equipment to do a full engine diagnostics test? I'm having the same problem and I'm considering doing it
Old 04-30-2012, 11:58 AM
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Changed the injectors
It starts up like the timings off anyway to check timing i tried with a timing light but there was no mark on the crank pulley to see if its in time
Old 04-30-2012, 02:26 PM
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Originally Posted by shadyredline
Changed the injectors
It starts up like the timings off anyway to check timing i tried with a timing light but there was no mark on the crank pulley to see if its in time
There is but they wear off...
Old 04-30-2012, 02:28 PM
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This does not sound like a timing issue, and base timing is controlled by the computer.

Does this misfire happen ONLY with a hot engine, ONLY with a cold engine, or BOTH? The answer to this question can help us narrow it down a bit.
Old 05-07-2012, 12:21 PM
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Originally Posted by bighouts5591
This is a known problem with the 4.0s called a "heat soak." Usually it affects newer ones but my 95 does it occasionally. Whenever you kill the engine all the heat from the exhaust manifold will heat up the cylinder 3 injector to the point that it will misfire. It can be resolved by wrapping the injector in insulating tape
Was wondering if you could point me to a link to the insulating tape to use
Old 05-08-2012, 12:51 AM
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it does it cold when u first start it up and it struggles to start and it starts after u turn the key for a lil like it doesnt wanna start and boom it starts and sometimes its got a real bad miss and sometimes it runs fine but i need to fix this to sell it

text me with any suggestions 7578148258
Old 05-08-2012, 01:37 AM
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Originally Posted by shadyredline
it does it cold when u first start it up and it struggles to start and it starts after u turn the key for a lil like it doesnt wanna start and boom it starts and sometimes its got a real bad miss and sometimes it runs fine but i need to fix this to sell it

text me with any suggestions 7578148258
May run a ground strap from the lip of the gas tank to the frame or reciver hitch my 94 did that not all the time but atleast a few times a week I grounded my fuel tank and haven't had a problem since,just my 2 cents worth!
Old 05-14-2012, 10:46 PM
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Originally Posted by nickxj94
May run a ground strap from the lip of the gas tank to the frame or reciver hitch my 94 did that not all the time but atleast a few times a week I grounded my fuel tank and haven't had a problem since,just my 2 cents worth!
ill try that and let u know if it does anything thanks
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