89' XJ Wont go past 1500RPM

to make a long story short, i put a tranny/tcase from a 96-97 into an 89.

before i started, jeep ran fine, drove fine no stalling, no backfires, nothing.

got everything buttoned up and it starts/ idles just fine, but now it wont rev up past 1500RPM.....

im afraid that maybe it has something to do with the torque converter?

i have checked cat,vacuum lines, connectors, plugs, wires, fuel press, etc.

has anyone else had this problem? if so, please help. im at a dead end.

BTW: its a 4.0 with AW4 and NP231


thanks a ton,
-Nick

Is that 1500 rpm in park, or drive?

park,drive,neutral,reverse.... doesnt matter, just tryed a tps and didnt change anything, im going to try a new cps next ( i didnt have to take it off, maybe i disturbed it?)

-Nick

"take what off?

CPS is worth a try, but sounds like two problems!

Are the flex plate bolts in the torque converter, attached?

I read something once about not getting the TC all the way in?

the torque converter should not be the issue. hunting down a small knock on my 89 i disconnected the torque converter from the flex plate to isolate the engine noise and not turn the trans at all. i had no problem reving the engine while the torque converter was disconnected and not spinning.
did you use your old flex plate when you did the swap to the newer trans? i am pretty sure the newer flex plates are different than the older ones like your 89 has. i believe the pick up ring that allows the CPS to get its reading are not compatable between the 89 (renix) and 96-97 (HO).

While I didn't think it possible, I had a cps that would limit the rpm's to about 1500 no matter what. It was only about 6 months old.

If you haven't been messing with the distributor and pulled it out, I would say cps.

2stix said:

the torque converter should not be the issue. hunting down a small knock on my 89 i disconnected the torque converter from the flex plate to isolate the engine noise and not turn the trans at all. i had no problem reving the engine while the torque converter was disconnected and not spinning.
did you use your old flex plate when you did the swap to the newer trans? i am pretty sure the newer flex plates are different than the older ones like your 89 has. i believe the pick up ring that allows the CPS to get its reading are not compatable between the 89 (renix) and 96-97 (HO).

Click to expand...

That is correct! I think he used the right one, but?

old_man said:

While I didn't think it possible, I had a cps that would limit the rpm's to about 1500 no matter what. It was only about 6 months old.

If you haven't been messing with the distributor and pulled it out, I would say cps.

Click to expand...

I thought I had read that before!!!!

sorry i didnt get back with this thread last night, but after a few hours of frustration, i did finally throw on a Crank sensor, it did the trick! not mad at it though, i know my jeep is in tip top shape now, after checking EVERYTHING!

i read somewhere that sometimes the wire going from the top of the intake to the crank sensor will contact the exhaust manifold just enough to burn through the insulation and cause a short, i can only assume that it was burned through in the first place but the previous owner tucked it out of the way, and when i did the tranny i moved it back on accident.


thanks for all the help!

-Nick