Im posting this for a buddy that's having a problem. So recently we just did a engine swapping his 95 xj and we got it all put in and everything but theirs one problem that's stumped every one that we've told. So here's the problem it runs perfectly up to 2500 rpm but right at 25 it starts missing really bad it almost seems like its in a limp haul mode and its shutting down the engine. We put a motor from a 92 in it...... Anyone have any ideas what could be causing this please let me know.



Things we've done already...... New plugs, wires, cap and rotor, checked timing,

 

Did you swap just the long block? The FI, distributor, and ECU were all from the '95?

 

we tried a ECU out of a 92 and the one in it and still did the same thing. The distributor is new as well with the rotor.

 

Check the coil. I had a chevy pickup do the same thing and changed almost everything just to find out it was the damn coil.

 

we pulled the coil off the 92 and has been running that since the swap and still the same thing, but the 92 is running his with no problems

 

You checked the timing at idle? Did you check it and see if it advances as the RPMs increase? I'm thinking distributor.

There was a thread here about a month ago where a guy had trouble after swapping a distributor, and IIRC, he had to set it one tooth off and then it was fine.

 

we took it to a couple shops and had the timing checked by them and they said everything was fine, we even had it put on a diag scope to see if that would find something and that came up as everything being good as well.

 

is the flywheel the same on a 92 and a 95 ?
did you use the 95 manifold with sensors or the 92 manifold woth sensors ?

 

im not sure on the fly wheel guess i should look up some part #s. and ya we reused the intake and exhaust manifold