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Random misfire all cylinders

Old Dec 12, 2021 | 08:46 PM
  #1  
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Default Random misfire all cylinders

Hey everyone just bought a 1996 xj 4.0 auto 4x4 that had been sitting for a year. Cleaned out the tank put a new fuel pump and filter. Started right up but had a misfire, so I put new plugs wires rotor cap crankshaft position sensor iac sensor tps sensor injectors ecu ignition coil basically everything I could think of. As well as cleaned every ground and connector I could see. As soon as you start it it has a slight miss then if you part throttle at 45mph it’ll choke and stutter. If you floor it it’s completely fine. I’m out of ideas and am open ears.

Last edited by Nikhil_q; Dec 12, 2021 at 09:05 PM.
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Old Dec 13, 2021 | 08:35 AM
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I know you just replaced a lot of sensors, but from what you’re describing is that it sounds like the TPS sensor. These XJ’s are really fussy about electronics, and if you put an aftermarket sensor on it, chances are it won’t like it.

Id start by testing the new TPS sensor on the throttle body, and google the specs for what it looks like at idle, WOT, and in between. If you didn’t go Mopar for the sensors, chances are that’s the cause
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Old Dec 13, 2021 | 06:45 PM
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Sounds more like the Crank Position Sensor. My 1996 XJ throws misfire codes when it is going bad.

First check its connection, clean it, no dielectric grease.
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Old Dec 14, 2021 | 08:31 AM
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I was chasing a similar misfire. Turned out to finally be the upstream 02 sensor for me.

Good luck
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Old Dec 15, 2021 | 04:30 AM
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What do you have for error codes?
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Old Dec 16, 2021 | 08:10 AM
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Originally Posted by Dave51
What do you have for error codes?

Don't start getting all logical now!!
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Old Dec 16, 2021 | 09:25 AM
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Originally Posted by cruiser54
Don't start getting all logical now!!
It's the only thing left, since

Originally Posted by Nikhil_q
...new fuel pump and filter. ...new plugs wires rotor cap crankshaft position sensor iac sensor tps sensor injectors ecu ignition coil ...
the Parts Cannon is out of ammunition...
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Old Dec 16, 2021 | 09:33 AM
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Originally Posted by Dave51
It's the only thing left, since



the Parts Cannon is out of ammunition...
I would have replaced the u-joints, the belts, the coolant hoses, and the fuses while I was in there.
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Old Dec 16, 2021 | 10:20 AM
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There's no easy way - get a shop manual. Assuming your air filter is clean, spark plugs, cap & rotor and wires are good, check for dangling wires grounding. Then open your shop manual and test your sensors: idle solenoid, MAP and TPS. If they are good and your throttle body is clean move to the injectors.


Testing restance in cleaned injectors

Pins can assist
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Old Dec 16, 2021 | 11:59 AM
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Originally Posted by Dave51
It's the only thing left, since



the Parts Cannon is out of ammunition...

which one?




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Old Dec 16, 2021 | 12:45 PM
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Old Dec 16, 2021 | 02:04 PM
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You know I stole that one second after I saw it.
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Old Dec 16, 2021 | 02:22 PM
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Yup.
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