I just swapped in a 4.0 out of a 94 grand cherokee automatic,into my 92 xj 5 speed.Every thing went smooth,meaning it runs and drive and what not.
THe problem I am having is that the swap motor has a rev limiter that kick's in at 4 thousand rpm's.My old motor did not kick in till well over five thousand.This is unexceptable to me,I need to figure it out.
When I swapped the motor's,I stripped the swap motor down to bare block.Then put all the componet's from my old motor on the new motor.Every thing except the distributer.
So I thought that had to be it,and swapped them.Now it wont even start,and before you ask,yes it was done correctly with the timing mark's and what not.(several times)just to make sure.

So how do I get it to run with out the rev limiter kicking in at 4 thousand rpm's???

 

Will it stop at 4 grand if in neutral? I doubt it's the rev limiter,on a 94 grand it would be around 5K-5500 but if it is it's probably a computer issue.

 

yes it kick's in neutral as well as in gear

 

Is it throwing codes at you?

 

Have not checked codes,forget how to get the ignition to throw them.How's that go again?

 

Checking.-> Computer codes

 

did u try to put the GC distributer back on and see if it starts?

 

Yes it works fine with the GC distributor but it only gets 4000 rpms. I need at least 5000 rpms.

 

Which ECU are u using?

 

My origional computer crapped out about a year ago,and I replaced it with one out of a 95 xj.

 

How did that perform before the engine swap?

 

The 95 computer worked flawlessly from the day I put it in.I have the computer from the swap motor and am going to throw it in.I would think the 95 would be compatable,but I was also thinking about the cpu,it's worth a shot.

 

Weighs heavy on my mind! Why do you need 5000 rpms? No good can come from running your engine at those speeds! Rotational mass at those rpms are self destructive. I understand that you don't want to be limited by the computer-But do you really have a need to turn those numbers, or is this a limiting factor that affects your daily driving needs?

 

Peak performance is at 4200 rpm i just need to get past 4000. I need to be in the power-band when I'm wheeling. I don't really need 5000 but 4500 would be great. I don't run it like that all the time just in spots where I need the power-band to kick in. I don't use this Jeep anywhere but off-road.