1091x

Ok so I am having a few problems with my 2000 XJ Sport, I threw a rod and so I swapped in a 98 4.0 motor and swapped everything from my motor to the 98, Everything swapped over fine, about 2 weeks ago I started to have problems.

Originally started with a flashing check engine light so I checked the codes, it was a p0300 * random misfire *.
It has a really rough idle, it idles anywhere from 200 and under 1000.
It will sputter out and die randomly.

I started with cleaning the throttle body and the IAC sensor, the IAC was damaged so I replaced that.

From there I replaced the TPS and still am having the problem with idle.

If it will sit sometimes it will not even turn over, I suspect it may be a bad CPS/CKS sensor, However I have no idea to it to see if it is bad.

Today it threw a 2 codes p0123 & p0122 both are circuit issues for 123 circuit high and 122 being circuit low.

Does anyone have an idea of what could be causing this?

cascadeclimbn

If it is idling sporadically and then stalling out I'd wonder if there was a vacuum leak somewhere...

1091x

I check the vacuum hoses and nothing seems out of place, however when I pulled one of the intake manifold vacuum hoses it actually started up and ran, it idled around 1000 but still idled, ( either the brake booster vacuum or the vacuum hose coming from the valve cover do this ).

cascadeclimbn

Hmm...thats strange. Ive never heard of anything like that. You could have hole on your intake. I had a similar idling problem with a 86 F150 i used to own and it turned out to have a little chunk of metal missing from the intake manifold. I patched it up with high temp steel bond (the gluey like substance that hardens like steel)and it fixed the problem.

cherokeeaddiction23

aka JB weld? haha love that stuff, i dont know much about the misfire, if it was a newer engine and it had the stupid coil packs id say check those but, i hate those things, those are the soruce of most of my misfires, happened three times since iv owned it so far

1091x

I haven't check the coil setup as of yet, the original motor had a distro and I swapped over my coil pack, I was told that the gaskets for in and ex manifold may be different since it's a different size on the ports, could this be the problem regarding all the Cel and rough idling?