Jeep YJ Build Up

Quote from deadfeat

At least you can by-pass the heater core for now.

thought about it, but a new one will be in tomm but at 45.00 i guess ill just finish it....

CJ-

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-

Quote from deadfeat

Wow,,, I'm getting ready to do a 4.0 in my CJ. But I am sticking to a 91-95 Cherokee motor. Keeping with the OBDI rather than the OBDII found in the 1996 and up. Still searching for my donor Jeep.

I hear ya, its a ton of work
Just to show what I used to fix it, a code scanner from Snap-On, it does OBD 1 and 2 as well as diagnostic for all commuters up to 2002, (my model goes up to 2002), this thing is great, i can modify rps, see all censor data, volts, and codes with specific details. I got if from the snap on guy for a deal, (since I bought it in 2010 and it only goes up to 2001). The best way to go about it is getting a good donor jeep, and then you can just transfer everything.



Good luck.

Cj-

Went out to a local trail for a little test run. Oil prssure sender is leaking like crazy but i will fix it this week.



Hopefully more hardocre wheeling before winter.
CJ-

Quote from WUZ749

DO you still have the stock axles and if so are you looking to sell them

Long gone, sorry.

Quote from BBD

the 60 in the rear is a big rock catcher
you may want to consider the ford8.8
I had one in my YJ on 35's it ran well

i know it is, it gets hung up on everything, i was thinking of building a 14b rear ford HP 60 combo this winter, or going for AAM Axles out of a ram 2500 or 3500.
Winter is here in Vermont unfortunately, and the jeep is all stored up till spring.

Cj-

Did a shakedown run the other day and played in the snow, the pit-bull’s did not like the snow, nor is the jeep heavy enough to compact the snow to make a nice trail. The jeep did great and pulled two stuck Chevys out of the woods. The transmission spit a bunch of fluid onto the floor, so I need to investage as to why it decided to do that, the stock rubber trans mount shook around a little too much, so I need to make some axillary mounts or a new more rigid mount. Also have found a company that will turn the digital signals from the computer to a signal my speedo and tach can understand. All 2000 late model OBDII systems use a single wire for all gauges, so to hook up an aftermarket tach and speedo. Moving in a week and will be getting a Garage!!! The biggest update is having a place to work on it.


Cj-