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Will not rev and rough idle after engine swap

baby ed

NAXJA Forum User
I just swapped a 4.0 out of a 98 xj into my 97. I swapped the throttle body, distributor, oil pressure sending unit, and coil off my 97 onto the 98 because the plugs didn't match on the 98.. Fired it up and its hard to start, idles rough, and it backfires terrible and will not rev past 2000 rpm...Im 100% sure the timing is right. I've checked it 3-4 X's now. I did notice today that I didn't hook the grounds that go on the dipstick tube back up. So I cleaned them and put back on... Still no difference. There is no check engine lights on, and I'm lost. Any help would be greatly appreciated.
 
Sounds like a distributor indexing problem. You are most likely off by one tooth on inserting the distributor. All you describe matches exactly.
 
I pulled the #1 spark plug, rotated the engine until I felt air blowing out. Then I kept rotating it until I lined the timing mark on the balancer up with 0. Then I made the rotor line up with the #1 spot on the cap when the dizzy was fully seated. I borrowed scanner from a guy at work this a.m , and I got 2 codes, even though there was no cel..... Codes we're p0135 o2 sensor heater circuit bank 1 sensor 1, and p0320 ign/dist engine speed circuit. .. found. Blown 15a fuse for the o2 sensor, and I swapped the cam position sensor out.... No difference was made
 
A P0320 code is " crankshaft position sensor signal failure"
 
try a new O2 sensor, when my O2 sensor went bad on my 99 it was running much the same, maybe you damaged it during the engine swap?

did you check for codes again after you replaced the parts?
 
Here's the latest..... Swapped the ecu, and o2 sensor off my donor. No difference. Went back and checked the timing, it was set correct. So I advanced it 1 tooth just to experiment, and it ran better, but it was too much. Any ideas on what could be going on?
 
Come to find out it was timing. My fsm wasn't right for mine. It showed the plug wires one position off from where they should be. Changed that, she runs great now. Thanks for all the help
 
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