www.MSruns.com read only forum (Jan.15,2018)

Name: Brian Harris
Vehicle: 1984 Jeep CJ7
Engine: 4.2L straight six with high output head from a 4.0L. bored 30 over, ford TFI ignition
Injection: MPFI using 1993 4.0 intake, injectors, fuel rail and sensors. MSII on a V3 board controlling fuel and spark using MS coil driver
Description: This is my off-road/sunny day play toy. It is lifted 3 inches with 31 inch mud tires and upgraded axel shafts and locker in the rear. It has a high output alternator from Powermaster and power steering from a full sized Jeep J20. This was my first electronics project (bought kit from DIY and built stim, relay and ECU) and first fuel injection conversion. I wanted to learn about FI and this certainly has fit the bill.
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i have a 1988 mj with a 258 4.2 liter that i would like to convert to mega squirt. it is throttle body. what do i need to convert? i would like to control gas, air, and spark. glens garage said the knock sensor might be a problem. can you help? dave

Dear Brian,

I have a friend with a 1994 (?) Jeep Wagoner here in the Philippines bought ex-military from Clark Airbase in Pampanga. It has a 4 liter straight six with multi-point fuel injection. Recently the injection control unit failed. Is this engine similar to yours? Would it be feasible to replace the control unit with a MegaSquirt unit? Would you recommend we try this?

Thanks a bunch,

Regards,

Dusky Lim

They are similar. My 4.2L in the CJ7 came with a Ford Duraspark distributor that is fairly easy to use with MS. The 1994 4.0 uses a crank trigger in combination with a cam signal from the distributor. The crank wheel (flywheel) uses a funny pattern that, to the best of my knowledge, MS does not work with. So, you would have to attach a standard wheel to the front of the crank (or have the flywheel machined), use a distributor similar to mine (it will work in the 4.0 block) or I have heard that there is a mid 80's Ford V6 engine that uses a similar distributor to the 1994 Jeep and you can replace the single window trigger from the jeep with a 6 window trigger from the ford, this would allow you to keep your stock distributor without the stock crank wheel.

Would I recommend the MS route, that depends on a bunch of factors. If you can't find an affordable junkyard replacement there then it may be the way to go. How much downtime can you have, how mechanical are you, do you have time to learn to tune, etc.....

Brian.