Still misfiring

TheJadeJeep944

TheJadeJeep944

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Dec 13, 2015
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I've put new spark plugs, new coil, new distributer, new spark wires, and a new fuel pump in it and it is still misfiring only at highway speed or when I try to hot start it. Any help is much appreciated. It's a 1997 4.0 automatic
 
Is it throwing any check engine lights? It should be if it's misfiring...
 
You should be able to retrieve codes by turning ignition switch on-off--on-off--on--off--on. The codes show up on digital odometer. On my 97 I have to press the trip button the same time I do it.
 
I think it's going to be like firing shots in the dark without a code. I would do as @UPJOHN suggested and try and retrieve the code manually in the mean time.

I'd be willing to bet it's likely some sort of sensor that's gone bad or going bad.
 
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UPJOHN said:
You should be able to retrieve codes by turning ignition switch on-off--on-off--on--off--on. The codes show up on digital odometer. On my 97 I have to press the trip button the same time I do it.
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I've tried this and all I does is run through all the numbers then nothing happens
 
TheJadeJeep944 said:
I've tried this and all I does is run through all the numbers then nothing happens
Click to expand...
Then you're doing it wrong. For your '97, simply turn the ignition switch on-off-on three times withing five seconds and then leave it in the On position until any diagnostic codes that are generated show up in the odometer display. If you do the procedure right, you'll always at least get a '55' code. Have patience, it takes several seconds for the diagnostic routine to complete before the codes will start to appear.

Do not push on the odometer reset button like you may have read to do on the internet. Doing that won't generate the codes, it'll just exercise the gauge pointers and run through the numbers.
 
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Chris said:
I think it's going to be like firing shots in the dark without a code. I would do as @UPJOHN suggested and try and retrieve the code manually in the mean time.

I'd be willing to bet it's likely some sort of sensor that's gone bad or going bad.
Click to expand...
The codes on it were P0340 and P1391

The codes on it were P0340 and P1391
 
Yes, from what I understand the cam sensor is inside the distributor, so perhaps a new distributor is in order?
 
2011-07-04_213654_jeep.png

I think this is it.
 
Once you get the distributor cap and rotor off, you'll see a thin plastic shield over the top of the camshaft position sensor. Remove that to get to the CPS where it is then easily replaced.
 
Super easy job, can't see it taking more than an hour and that would be taking your time.
 
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