Swapped engine problem

Just finished putting an 88 engine into my 90. The swap has gone fairly smooth, only a few problems untill now.

I was told that the engine was straight out of a front/side impact wrecked cherokee, and ran good when wrecked. It wouldnt run initially, but after replancing the mysteriously missing ditributor rotor and re-indexing it to correct the timing. It runs now.... Kinda.

It idles horribly, like it has a bad miss, but killing each cylinder one by one it ran slightly worse with all of them which leads me to belive that its not a single cylinder problem. So that points me back to timing; non-adjustable. ok, on to fuel. The gas has been in the tank about a year. Anticipating this problem i added some fuel stabilizer a few days back. It didnt help or i am looking in the wrong place.

What else should I look at?

Another mysterious symptom is that opening the throttle does nothing except make the engine sputter and cough and will cause it to die if the throttle isnt closed back up. what the hell?

Do a search on distributor indexing. There are other things that can cause the same symptom. A bad or disconnected MAP can cause major problems. A bad TPS can cause issues. A bad vacuum leak can also cause problems. Double check the spark plug wires are on the correct cylinders. The order is cast into the intake manifold.

Mine did that when my fuel pressure was real low. I measured it at the rail only 20 or so psi s/b 39 i think.

I kinda think it is a fuel problem since the pressure at the rail has been real erratic.

Another mysterious symptom is that opening the throttle does nothing except make the engine sputter and cough and will cause it to die if the throttle isnt closed back up. what the hell?

Click to expand...

this is what puzzles me the most... what could cause it?

I replaced mine a few months back with a helper working under the xj. He undid a bolt that he thought went through the bell housing to the block. He did not put it back in when the new motor was installed. It run at idle then when you gave it any gas it was real eratic and rough. It would not rev over 1000-1250 rpm. It took me a month of searching to finally notice that bolt sitting in my spare parts bucket from the swap. It went to crank shaft positioning sensor which was not aligned causing my problems. Put the bolt back in, started it up and I have been driving it with no issues since.

THEY ARE NOT ALWAYS SPARE PARTS!

Hope this helps.