JEEP 4.0 Success - UAEFI
Posted: Mon Jul 22, 2024 8:38 pm
Tune file: https://rusefi.com/online/view.php?msq=1729
--------------------- 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. 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).
Things I am not asking the ecu to do:
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!
--------------------- 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. 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).
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.
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!