Tune file: https://rusefi.com/online/view.php?msq=1729
---------------------1000002007.jpg
This Jeep is a 1984 CJ7 with a 4.0 out of a 98 Grand Cherokee. When my father acquired the Jeep sometime in the 90's, it had a 4.2L carbureted engine and a soft top. It had no a/c, a few distasteful modifications (hammered hole in firewall, drilled holes), but was in pretty good shape.1000001903.jpg
3803.jpg
Fastforward 30 years, and now he has given the Jeep to me. The first thing I wanted to do was address the engine, engine bay, and clutch.
After some research I discovered the newer 4.0 engine was pretty much a direct bolt in replacement (at least bell housing, motor mounts, clearance), so a running junk yard engine was purchased. That engine was rebuilt using stock specified components, and the bell housing was modified for a crank position sensor. The original transmission (nwc T5) only needed an adapter pilot bushing to be installed in the crankshaft. For the ignition system I went with a three coil (wasted spark style) coil pack and added a coil driver to it. The fuel system is stock except for a fuel pressure regulator mounted to the intake manifold. The clutch was converted to hydraulic using oem style parts for a four-cylinder cj7 (custom length slave-to-fork engagement rod). The stock A/C compressor was adapted to a Jeep Air under dash unit (works great).
1436.jpg
1534.jpg
894.jpg
1000000604.jpg
1000001792.jpg
Things I am not asking the ecu to do:- directly drive the alternator field coil. I'm using a big solid state relay under the ECUs control.
- control wideband O2 sensor. I had already installed a 14Point7 device.
- control a/c compressor. Engine idles up when the compressor turns on because it reads coil state. I added a diode on the compressor coil for extra safety.
Overall impression
I am quite impressed with how the engine runs and its street mannerisms. A/c idles up, manual shifts are smooth thanks to "dashpot" settings, deacceleration-to-stop is smooth, acceleration is crisp and responsive, and cold start is quick. The previous ecu was a MS3, but unfortunately, I damaged the circuit board, and it was cost prohibitive to replace. For a much cheaper price I got the UAEFI (ultra affordable efi). Not only is the UAEFI smaller, it has all the features I need (plus more), required no hardware modifications, and is cheaper to replace if I make a major wiring mistake. Furthermore, I can research and/or modify every feature of the device using the open source code bank.
The Jeep project chapter may be closing for me, but with so much power for so little money, I see a lot more projects in the future!Statistics: Posted by scfrontier — Mon Jul 22, 2024 8:38 pm
]]>