dale

was wondering if anyone knew the part number needed for a 99 cherokee. we just bought the car and when you turn off the key the engine diesels. changed the throttle body and sensors, wasnt the problem. it looks like the computer has been messed with, so thinking maybe that could be the problem. the part number on the computer is 492AD. some guy on craigslist had one for sale. bought it, put it on and the car seems to be running on 4 cyl. part number 801AD. so the computer is either bad or not for the right year. does anyone know what could be making the car do this?

89Laredo

The ECU has to have the VIN programmed into it to run right.

dale

car does not shut off when u turn off key, looked into it and someone has a constant hot wire running to the small 15 amp fuse, the fuse is out, so we flipped up the fuse panel thats underneath the hood, theres a red wire and we traced it and it runs to the ads relay. cahanged relay and had it checked, its good. if you take that hotwire off it wont start, but if you take it off while running it stays running. cahnged the throttle body, that wasnt it. changed the computer but seems to run on 4 cyl. so put old one back on. changed fuel pump relay, hadf it checked, its good. dont know what else could be. could it be the crankshaft position sensor. or another relay. you were saying about the ecu needs to be programmed, who does that? a dealer?

farmfuel

carburetored engines diesel because the timing is too delayed/retarted. Check your timing with a timing gun. Also take off the distrubuitor hold down clamp and see if someone ground down on the retainer that is cast into the distrubuitor shaft. Some folks do this in an effort to change timing. The engine computer adjusts fine timing, but the distrubuitor has to be stabbed correctly to establish base timing. If someone ground off an ear on this retainer that's cast into the dizzy housing- this would tell you that someone has tried to change base timing. EFI engines aren't supposed to have "adjustable" timing, but you'll still find a timing tab on the timing chain cover. Take a bottle of white out, and find the mark on the harmonic balancer. Dab the white out so it seeps into the crack, and wipe off the excess. Now take your timing gun and go to town. I'm not sure what it's supposed to be. It may be on the data sticker under the hood. Timing on most EFI engines is 10 degrees before top dead center. Look it up to double check.