So these past 5 weeks I have been trying to figure out why the jeep was running so shitty, and it seems that there were a lot of factors that were at play here. The jeep would not idle, it would sometimes idle and then cut out, and often it would not run over 2k rpm. So with a buddy's help and a snap-on computer we began to diagnose the problems.
First issue was the extra voltage and not idling factor, after several days of looking and testing bob figured out that the tachometer signal wire I had added was sending the incorrect voltage to the CPU, so it was either pulling to many volts or adding voltage to the system. Result was consistent rough idle. But now runs without cutting out.
Second issue was the fuel injectors, I had a cut and melted injector, it was fouling in the #4 cylinder, I ordered new Bosch Gen 4 Dodge Neon injectors with 4 injector holes, changed all the injectors and cleaned nasty fuel rail. Result, more stable idle but still cuts out over idle.
Third issue, clogged fuel filter, you assume this would be the first thing I checked, which I did, but not until reading the Mopar service manual I learned that on TJ’s there is a pre filter on the pressure regulator. So I pulled the regulator and lines out of the tank and cleaned them. Fuel pressure returned. Result, smooth idle, runs up to 2-3 rpm and then cuts out.
Fourth issue, the motor is out of a 2000 jeep with California emissions, the computer relies heavly on oxygen sensors to run correctly. The rear bottom oxygen sensor was cut, un-noticeable until I pulled it out, other O2 censors read between 1-3 volts, the trouble maker was 4-5v. So I replaced it. Result, much better idle and still cuts out but not nearly as often.
Fifth issue, intermittent loss of CPS or CKS. Crank position sensor and cam position censor. Both were bad, I think from the voltage spike from the extra tach signal, but replace both. Result, ran much better, cut out only a few times.
Sixth issue, no B+ power to ECU, so it does not remember previous cycles. Still working on this one
Seventh issue, cam position censor needed to be adjusted, trial and error, moving slightly until, smooth idle, start up, and no cut outs. Result, runs better than it ever has and works as it should, no more big issues.
So this is what I have been doing, I also in frustration pulled the entire wiring harness, rechecked all wires, and re-taped and tested circuits.
Overall this was a nightmare. I don’t recommend an engine swap across model to anyone, YJ-TJ and such, or if you do please avoid anything after 2000 or with California emissions.
CJ-