Help XJ gods.....

My sis has a 93' xj that has been acting up. We have replaced just aboot everything, and now we are at a loss.

The Jeep will crank and crank and crank, but it will not fire untill you crack the throttle and let off the key. From that point its a crap shoot weather or not it will start. It also starts to miss once it gets above 2k RPMs, unless it gets good and hot.

So Far we have replaced:

Battery
MAP
TPS
CPS (Which was a bitch to get to... but thats another story)
IAT
Plugs
Wires
Cap
Rotor
Distributer
Coil
Swapped in a computer from another jeep, didnt help, but both computers work in the other XJ
Cleaned the TB
Put a can of Sea-foam through it
Fuel Pump



The plugs keep getting fouled out real bad.

we are pretty sure the problem is electrical, but this has stumped even my father who is an ASE certified master mechanic w/ 30+ years of experience at a Jeep Dealership.
If you have any ideas, please let me know.
Thanks

when it starts is it rich?
Does it flood?
have you checkd fuel pressure?
93 should have a fuel return line, I think, make sure it's not obstructed, and check the fuel pressure with the vacuum connected and disconnected.

Any fault codes stored in the PCM?

Ok I know some vehicles have a second power source when engine cranking for the coil. To see if the is working or not, put a direct power wire from the battery to the positive side of the coil. Then if it runs while cranking then you know that circuit is bad. That is the first step I would try.

Have you tried a Camshaft postion sensor?

When you replaced the Distibutor, you double checked that it's not 180 out right?
There's that little ceramic condenser on the driver side fender. Try jumping the wires together. if it run w/ them jumped, the condenser is bad.

Best of Luck

Rob

FELIX said:

When you replaced the Distibutor, you double checked that it's not 180 out right?
There's that little ceramic condenser on the driver side fender. Try jumping the wires together. if it run w/ them jumped, the condenser is bad.

Best of Luck

Rob

Click to expand...

Test and idea correct, terminology not: it's a resistor. Not all XJ's have them. I think your 93 does. In my family, 87 didn't, the 88 and 89 did, the 93 did and the 95, 96 and 99 don't. Go figure. Anyway, it's inessential like an appendix or a plica, so if it misbehaves, leave it off.

It sounds like your distributer is 1 or 2 teeth off. Also you might check and/or replace the ground wire from the engine block to the firewall.

mrbill3 said:

It sounds like your distributer is 1 or 2 teeth off. Also you might check and/or replace the ground wire from the engine block to the firewall.

Click to expand...

Good points both.

Maybe one tooth advanced. When I tried this on my 87 I found one retarded starts beautifully but cannot rev. One advanced produces symptoms like those described, hard start, but ok running once the ECU takes over timing. More than one wouldn't work at all.

That wire on the firewall can look pretty good even when it's actually turned nearly to dust. Worth a good check.