Have a 90 xj 2 door 4.0 I can idle it but then it dies when hit the gas I've tryed to do the vac lines because they were not on when got it. I bought two at same time people befor had one had a fire under hood so they bought a good running one to rebuild the other I have no idea why they got running but same problem I described berore so I took everything they did and put back on other one and same problem ?

Did you test your CPS yet?

Its your o2 sensor on your exhaust manifold. I had the same issue

No what is that ?

Yes it's right under the intake is that what was wrong with yours ?

Crankshaft Position Sensor.
It's on the bellhousing at the back of the motor by the firewall, and it's a ***** to get to unless you A) take off the crossmember and lower the trans/t-case, thus tilting the motor down in back B) remove the intake manifold and header C) have tiny, tiny hands.
This sensor sends vital info to the computer regarding the position of the flywheel and crank. If it starts to fail, you will have crappy running and all sorts of undesirable behavior. There is a test for it as described here: http://www.lunghd.com/Tech_Articles/...iagnostics.htm

The cps is so easy to replace I can change them in 10min u just need a socket wrench with a swivel attachment and a few extensions

Luke could be correct, I've heard these symptoms as a result of a bad O2 sensor as well. But, my '89 Renix exhibited the same symptoms and it was the CPS. As Stev-O said, it can be done fairly easy if you have access to a long extension or several short ones that can be linked together. I used a 30" 3/8th extension with a 15º Snap-on wobble (Craftsman and Husky make one, too). Like Stev-O, I can change mine out in about 10 minutes.

Follow the test procedure linked by desertdog and see what you get. Good voltage isn't a guarantee that there isn't a problem with the CPS but it does reduce the likelihood. If you do end up swapping it out, I suggest going in feet-first from the driver's side, it gives you a much better angle on the CPS with both the ratchet and your hands.

I use the same technique for removing transmission bolts....long extensions and a taped u-joint. Only took me about an hour to drop a trans. I still think the CPS would be easier to get to with the crossmember out.

Ok the only problem is that on both motors it does the same thing the odds of both being bad idk I have to test. I've taken egr valve egr thing on fender map sensor TPS and swapped from one to the other. I took a map sensor from another xj and same thing so I think it's not that ?

U don't need to remove the cross member or anything it's not in the way just need a u joint attachment with tape on it so u can get the angle without have your hands all the way crammed in there

I can only get to idle and rev higher if I slowly ease into it if smash it die even with new map sensor. Any one know how to test o2? It also it smells real rich anybody have a pic of the vac lines on your rinex motor ?

Not sure where this goes too

Looks like the diaphragm for the EGR valve.

I know it's not in the way, I was referring to being able to lower the back of the motor a bit. But I believe you when you say it can be done, I just haven't tried it personally.