HELP ME!!!!!!!!

[vavs]

Just got done "bolting" the 4.0 into my 2.5 and now I cant get the engine to fire up. When the fuel pressure reaches the correct level the computer seems to cut the power to the ignition. Anyone know what might cause this cut is voltage? Any help would be great! Thanks.
Vavs

 

[avyoung]

Sorry No Idea.

 

[Tug-n-pull]

Did you change the computer out as well? Is there a difference in the 2 engins computers? I really have no way of answering so I will just try to jog some ideas for thoes that have a better handle on this sort of deal. tug

 

[Snitty]

there most definitely is a difference in the computers... remember... not only will the computer be different.. but the tachometer and possibly some other gauges will be different

 

[jeepin916]

what year is the jeep? the computers are different and the 4.0 wont run on the 2.5 computer. is it a newer jeep? TJ? YJ?

 

[vavs]

I changed the computer, and all the wiring. It is all different for the two motors. The motor I put in is out of a 1994 Wrangler, and mine is a 1995. What happens is, I turn the key on and everything has power for about 3 seconds, then it all turns off and everything is dead. By everything I mean the ignition system. There is a wiring harness that is not connected under the dash. I dont know where it goes, that might be the problem. There are harness's that come throught the firewall tward the center of the engine bay. One of them goes to the heater, does anyone know where the other goes, could ya look? Any help would be awesome!! Keep in mind that my wrangler does not have air conditioning, or ABS. Thanks.
Vavs

 

[jeepin916]

sorry but this question is not relating to your jeep problem but did you have to change the motor mounts for you swap?
and back to your jeep problem,.... have you checked to make sure all your connections have a good contact? if your getting power for a few seconds and then losing it you could have a bad connection somewhere.or maybe the computer is no good does it start at all?

 

[vavs]

To do the swap I had to cut off my 2.5L motor mount perches and weld in new 4.0 motor mount perches about 4 inches ahead of where the 4 banger mounts were. I didnt know that would have to be done before I bought the motor and stuff. Yeah, I was mad when I got to looking at the new engine and the old mounts. If you are going to try the swap you will also need different length driveshafts. I was lucky and had pretty much a whole jeep to pull parts off of. The motor turns over and everything, just does not fire. If someone could look and see where that wire goes it would be a real help! Thanks again.
Vavs

 

[Craig]

Mabye you have 4.0L HO and the computer you have is out of a regular 4.0L or opposite. I don't know if there's a difference in the computers between a 4.0L HO and a regular 4.0L but there is a few differences between the two motors.

 

[vavs]

The wiring and engine were out of the same wreaked Jeep. So I know all the wiring works with the eninge I have. The only thing I dont know is where the wire goes under the dash. I really need help with that, I think that might be my problem. Thanks.
Vavs