anyone have a 93 computer & 4.0 question

Does anyone out there have a computer laying around for a '93, 4.0, auto with air? No parts stores around here have one and every wrecked jeep I find is '90 or older.I have tested and everything came back to the puter.

Question, would an '87 4.0 be a good motor to build up for my 93 and would my intake,exhaust and accessories bolt on.I know I will have to use my electronics.Thanks, Richie

No computer here....but....try http://www.jwjeep.com/ they have hundreds of jeeps...and ship parts for cheap....will run you around $100( i think)

As for the motor....a 87 has a different head, which means your intake will NOT mount up to it. Most of intake and electronics are different. You will need a 91 or newer head to build up so that everything matches up to your current setup, but you could build off of an older block, which is more or less the same for most years.

I have a 93 computer, but I'm not ready to sell it (spare for an XJ still in the family). It might, however, be possible to do a loan as a way of checking if it really is the computer, if you wanted to cover the shipping both ways. I won't be back home where I can get at the thing until next week. I should mention, though, that the reason I have a spare computer at all is that all the diagnoses pointed that way on my stepson's 93, and it wasn't that at all. It was a wiring harness fault - specifically a bad splice. The dealer was going to charge nearly a grand for a new computer, but after a bunch of false leads and new parts it was fixed with a foot of wire and a soldering iron.

So the next question that arises is: what symptoms do you have, what codes are coming back, and what have you tested?

Hey Matthew, I have replaced the fuel pump, filter,crank sensor,cam sensor,coil,removed and cleaned IAC motor,fuel rail,each injector,have plenty of fuel pressure,back traced the asd relay and have 12v coming from it and going into the computer.We have 12v coming out of the computer. The jeep will start when it is cold and will run for about three or four minutes and then die.Sometimes it will start and run again for a short time and die again.Then it will not start at all.I can pour fuel down the throttle body and it will fire up until the fuel burns out.All my sensors check out,I have spark and fuel to the rail.I am at a dead end here.
I appreciate the computer offer but would hate to get it and try it and something happen to it.I can barely afford one computer much less two.By the way, where was the wire at they had spliced and what did it control.It never hurts to ask.Thanks, Richie

richie said:

Hey Matthew, I have replaced the fuel pump, filter,crank sensor,cam sensor,coil,removed and cleaned IAC motor,fuel rail,each injector,have plenty of fuel pressure,back traced the asd relay and have 12v coming from it and going into the computer.We have 12v coming out of the computer. The jeep will start when it is cold and will run for about three or four minutes and then die.Sometimes it will start and run again for a short time and die again.Then it will not start at all.I can pour fuel down the throttle body and it will fire up until the fuel burns out.All my sensors check out,I have spark and fuel to the rail.I am at a dead end here.
I appreciate the computer offer but would hate to get it and try it and something happen to it.I can barely afford one computer much less two.By the way, where was the wire at they had spliced and what did it control.It never hurts to ask.Thanks, Richie

Click to expand...

The Chrysler system switches the negative side of the injector circuit. I can't recall the exact circuitry of the positive (away from home and manuals), but it comes from one of the relays, via the distributor, through a harness, to the individual injectors. At various points within the harness are splices which branch this intial single line out to all 6 injectors. The wires are just crimped together with a metal clip. One of these splices was defective, and what happened was that the Jeep would start and run perfectly until it heated up. At this point, the resistance of the splice would heat it up, the resistance would rise, and one of the injectors would cut out. It was very difficult to diagnose because it was intermittent. I finally found it after various tests. The resistance of the bad splice when it was cold was not very high, but enough to turn it into a little heating element whose resistance rose just enough to kill the injector (but not enough to register dead on an injector harness tester!).

My problem was less drastic than yours, and took a good deal longer to develop (it occurred in cold weather, and sometimes it would run fine for an hour, and only misbehave after restarting hot). Your problem does sound as if it could be a computer failure from a component heating up. Nonetheless, before buying a computer, considering the cost, and the chance taken, I'd first look for a wiring diagram of the system and then check every single piece of the harness, wire by wire, with an ohmmeter.

thanks Matthew!

Well I got with a friend of mine and went on the Mitchel -on - demand computer at work and printed out some wiring diagrams.We traced the wiring back to the injector power wire(that pesky little grean\orange one).When I got home I read your replay and went outside to attack it.I fired it up and wiggled the harness at the rear of the motor and it shut off.I tried it again and the same thing.I peeled back the wrap and found that the green\orange did as you said and spliced into several other wires.It had two strands of wire still in cantact with the rest.I did not find any metal crimps but instead they heatshrunk and glued the wires together.They must have went over budget in the connector dept. that month.I cut and resoldered them all together and did the same to all other spliced connections .That fixed it.Thank you so much for pointing me in the right direction.We were headed that way but you hit the nail on the head.If you and the familyare ever in Florida, look me up and I'll take you to Disney.Thanks a bunch,Richie

It sure is gratifying to be right every once in a blue moon! I wonder if this problem is specific to 93's.