Any Mitsubishi 2.4L Engine experts here?

[Raven]

My friend who does not have a computer has a strange problem with his Mitsubishi truck. His '91 Mighty Max, a 2.4 liter/5 speed, seems to only be running on 2 cylinders - #1 and #4. Is that even possible?

If he pulls the plug wires off of #2 or #3 cylinders, the truck keeps running. However, if he pulls the wires off of #1 or #4, the truck dies. The spark plugs out of #1 and #4 were dirty but the ones out of #2 and #3 were fairly clean.

There is good spark at each electrode and the compression tested good - ~126psi all around.

What could be causing this? The truck vibrates a lot but then again, so do most 4 cylinders.

Is it possible? Could it be the injectors? Could it be the computer not firing the injectors? Or, is this a unique situation to the 2.4 liter 4 cylinder motor? Any and all information and suggestions will be appreciated!

I've posted this question over at the Mitsu forums but no help so far. Anyone here familiar with this motor/problem?

Help???

 

[Turbo Indian]

check the rice level, it sounds like it could be low. HEHEHE

I couldn't resist

 

[2QWIK4U]

I'm parts mgr at a Mitsu dealer and from my experience I would bet on the computer.NAPA can have them rebuilt for about $250,new from Mits is from $900-$1400

 

[cwelk87gn]

I'd second the ECM suggestion. It seems like Mitsu computers go out on a regular basis and they are neither cheap nor plentiful.

 

[TurboJim]

Is this truck distributorless? If so, the 2-3 coil is bad. If not, make sure the wires arent crossed in the cap, and there isnt oil puddling in the dist cap causing those cyls to short. Common on imports.

Kinda weird that its the 2 paired cyls if its got a distributor..

Firing order is 1-3-4-2, 1-4 are one coil, 2-3 are the other if its DIS.

I doubt its the ECU, they usually are a no start if the ECU dies, in my experience anyway..