Random break downs

[98XJblack]

So it's been a while since I've posted on here which was when I discovered that the engine in the 1998 xj we purchased had blown piston rings. So we put a new engine in and got it running. Took her on a road trip from Boston to Cleveland, Chicago, st.louis, Nashville and back home, no issues. The current situation is random.

So on the highway mostly it will start to lose power with no response to the accelerator until we pull over and let the car catch up to idle and respond to the gas pedal. It will do this a mile at a time until it decides to run solid.

Work done up to this point: TPS, CPS, O2 sensors (first and second), fuel pump, engine, radiator, exhaust, amongst many other mechanical repairs which would not apply to the proper operation of a motor.
I have a feeling it could be electrical and I thought I found two grounds on the engine block that could be the cause and I reworked those but after a week of running good it happened again.

Any testing or thoughts on a possible cause would be appreciated.

Thanks

[nickyg]

MY 96 has a sensor under the disturber cap. Might be worth replacing if your not sure of it's condition.
Not sure if your 98 has one or not

[98XJblack]

I'll look into that because I think I've had codes for such sensor and not replaced any such part.


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[98XJblack]

Just thinking about it but is the camshaft sensor and crankshaft sensor potentially the same thing


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[4.3LXJ]

No, they are two different sensors. CPS, crankshaft position sensor, is located on the bell housing. The CKS, camshaft position sensor, is located in the distributor and is on all models with a distributor

[Carves]

Just thinking about it but is the camshaft sensor and crankshaft sensor potentially the same thing

Only in that they are the same "hall effect" style of sensor and can give off similiar symptoms when faulty.

Otherwise its as 4.3LXJ described.


Might be worthwhile borrowing another TPS for a while ... as a test ??

[98XJblack]

Ok thanks a lot guys


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[cpttuna]

I would guess something electrical. My 78 Bronco would all of a sudden just quit running. Then after about an hour sitting, it would start back up and run fine. I finally took it to the repair shop and they started it up and let it run. When it got hot, it quit. They traced the problem to a wire on the distributor.

[98XJblack]

upon further inspection of my 98 xj there is no camshaft sensor at the distributor. All wires at the distributor seem to be intact and undisturbed. Next step I suppose is to take it to a shop and have them go through it with more knowledge and tools and time.

[Pookapotamus]

I did not see a fuel filter in the list of things that you did, not sure if the 98 has it in the tank and you replaced it when you did the pump or its on the "frame".

see if you can get your fuel pressure tested while you are driving, soulds like a loss of fuel.

other than that, have you done the easy maintenance? cap, rotor, wires?

pook

[98XJblack]

Yea the filter is part of the pump assembly in the tank with the 98. It does seem like a fuel issue and I drove it into work this morning no issues driving. However I am sitting at the job site idle right now and I can feel the engine missing and holding a hard 800rpm. I have not looked at the distribution much since I replaced cap and rotor and tested wires for spark when I replaced the motor, but it is worth a look.

At the same time maybe someone with a fresh head is going to be better than me at this point. Blah


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[jimmixj]

Hi Jon,
If you have the 4.0 inline 6 in your 98 it should have an auxiliary filter mounted on the frame rail above the rear axle on driver's side. It is a largish can bout the size of a shorty beer can. Also, I've fallen pray to the assumption that because a part is new it's good. Have pressure and volume tested on that fuel pump just to be sure. Problem with any diagnosis of fuel injection is the interconnectedness of systems; a problem in a given area can often show up disguised as something else. A simple test would be to put a spark tester ( an inexpensive tool available at most auto parts stores) inline and try to "see" the misfire. If the engine's missing but the spark pattern at coil looks good, chances are good it's a fuel-related miss. Just a thought...