1993 cherokee very rough idle/misfire

I have a 1993 xj that has been misfiring. So to start this all began at about 1300 miles into my 1500 mile trip. The jeep died on the side of the road. I started it back up and it ran perfect for another minute then died. Did the same thing one more time until it would no longer start. Had it towed to a shop in a small town.

At the shop I told them I had a problem with my coil about 2 months back so I recommended they check it out. Instead the shop started going through parts. First they replaced the magnet pickup in the distributor. No luck, next up was the cap and wires, again no luck. Finally they tested the coil again and found it was in fact dead. Replaced it and it started up.

However it now runs terrible, misfiring only can keep it running for a few minutes before it stalls out.

I gave up on the shop and just towed it home to work on it myself.

Checked all the plug wires right when I got home and they all lined up fine. I had assumed that they had thrown the timing off so I went to adjust the timing. This is when I realized timing was controlled by the computer.

So now I am here and I do not know where to start. I find it very strange it ran perfect(except the coil) before it entered the shop.

Was thinking about ordering a refurbished computer from online. Any suggestions on what it could be? Might I look into a new distributor?

Doubt it's the computer.

Check fuel pressure? Check spark plugs? Check upstream O2 sensor?

I also doubt that this is the computer. Misfiring rarely is.

I agree that fresh spark plugs, replace or at least ohm out plug wires, new distributor cap and rotor and verifying fuel pressure with a GAUGE would be a good start.

I also would perform the key-on, key-off technique to see if there are any stored codes to give you a clue here. Only takes a couple of minutes. You can have stored codes, even if the check engine light isn't on.

http://www.go.jeep-xj.info/HowtoECUcodes.htm

birchlakeXJ said:

I also doubt that this is the computer. Misfiring rarely is.

I agree that fresh spark plugs, replace or at least ohm out plug wires, new distributor cap and rotor and verifying fuel pressure with a GAUGE would be a good start.

I also would perform the key-on, key-off technique to see if there are any stored codes to give you a clue here. Only takes a couple of minutes. You can have stored codes, even if the check engine light isn't on.

http://www.go.jeep-xj.info/HowtoECUcodes.htm

Click to expand...

Will try the key on key off

Plugs changed about a month ago. Cap and wires both changed while it was in the small town shop.

Also fuel pressure was checked at shop as they thought the original problem was the fuel pump.