tk421_93xj

Ok, so I have a 1993 XJ 4.0 i just had to replace the motor in. we are running all the factory parts. I have no spark. Fuel pressure is good, replaced cap, rotor, wires, plugs, coil, Crank Pos Sen, and still nothing.Shes been down for two months now and we cant seem to figure out why i cant get spark. Any ideas????
:h elp::hel p: :h elp:

tjwalker

There are a number of possibilities, but you need to verify that your ASD circuit is operating properly. For starters, try swapping your ASD relay in the power distribution center with another relay. They are of the same part number, so swapping is not an issue. Below is more on the route of spark for the HO 4.0 engine.

Also verify that the wiring for the crank sensor has not been damaged, a very common issue when an engine is swapped. Follow it all the way up into the engine bay.
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Spark: 12 volts from ignition switch to the ASD relay; when the key is first turned on the PCM provides a ground to the ASD relay to energize it, then the ASD relay passes 12 volts to the coil primary side. If no crank sensor signal is generated after a couple of seconds the PCM cuts the ground to the ASD relay (and fuel pump relay too) and that cuts power to the coil (and fuel pump). Key to START and once again the PCM energizes the ASD relay. Now, a critical element is the crank sensor--no signal from the crank sensor and the PCM won't trigger the coil to provide spark.

Roler

CPS is recommended to be quality one.
I know you said you're " running factory parts" but did you replace the CPS with an OEM, or an aftermarket? Aftermarket CPS tends to be unreliable compared to the OEM.

tk421_93xj

Ive checked the ASD relay and its fine. Ive got pulsing from the CPS and i replaced it just in case. Still nothing

tk421_93xj

@Roler i replaced the CPS with one straight from the dealer

RTorrez1

I know you changed out the crank sensor but have you checked out the cam sensor? Just something else for you to check.

tk421_93xj

@roler they did not put cam sensors on any model before 2001

tjwalker

They all have cam sensors, pre 2000 are inside the distributor. Some parts stores though call them different things.

tk421_93xj

@tjwalker is that the plug that comes off of the distributor? when i turn the key over it pulses neg then pos.

RTorrez1

They sure do have them.

ajcallea

Have you checked the ignition switch or any of the wires for it??

Roler

Please quote the correct forum member next time. I never mentioned cam sensor...unless you think CPS related to that....please see below.

"coil pickup" sensor or something the likes wasn't it? Some call it the cam position sensor and they all use the same abbreviation as the crankshaft position sensor: CPS..

I'd say so, last time I looked...

tk421_93xj

well since noone knew on here, i took it to the dealer. and its NOT THE CAM POSITION SENSOR, NOT THE CRANK SENSOR, NOT A ""COIL PICKUP" SENSOR", It is the PCM. Seeing as how everyone who replied had me running in circles checking the same things. Thanks alot for the "help"