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Thread: My new (old) 1992 Mitsubushi Mighty Max

  1. #1

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    My new (old) 1992 Mitsubushi Mighty Max

    Hello to all folks on these forums.

    I found a 1992 Mitsubishi Mighty Max, 2.4 4 cylinder 5 speed manual trans late last year. Seemed to run pretty strong when I got it and drove it for 150 miles from where I bought it to where I live. About 20 or so miles before I got home the "Maintenance Soon" light came on, not the "Check Engine" light. Parked at a packing lot and checked what I could at that time, not finding anything I started the motor back up without any new issues and drove home.

    Few days there after and some other checks further, still not being able to find anything. I started the truck and neither lights came one, aside from them lighting up to show they still work. Drove her to work and back, I did toss in injector cleaner on the way home which seemed to have caused something just before hitting the high way and soon there after then engine seemed to run fine again and took me home without issues.

    Went to pick up my son from work in the weekend and she barely started, it being down hill to where he works went all right but after that climbing back up hill was a mess and felt like she would not make more then 300 RPM and stuttering horribly. There not being a tacko on these truck I have no idea what the RPMs really where, just that is was very bumpy getting back up hill on a smooth road.

    Now about 8 months later my little truck is still parked in the back of the drive way still not really running.


    Here is a filled out copy of the advice of the first post recommendations :

    #1: Replace Timing Belt.
    No idea when this was last done when I got it. This engine has 2 belts and when I took the cover off I noticed the secondary or "B" belt to have failed. This failure bent the plate that separates the "B" belt from the main time belt on the crank shaft sprockets. This in turn caused the main time belt to fray on the engine side and half of the width was gone due to the plate cutting it down every time it passed the bent piece. Both belts have been replaced with the help of the Haynes manual and several 4G63, 4G64 manuals found online. The plate has been fixed, 2 new belts and 2 new tensioners have been used.

    #2: Replace the Fuel Filter.
    I found a lot of rust in the filter when I went to replace it. Traced the rust back to a very rusty fuel tank. Used my own magic mix to remove the rust and treat the tank from rusting again like that. Most of this can be found online, look for remove rust from fuel tank, I used a combination of several finds to use chemicals I had nearby. Flushed everything and made plenty of waste fuel that way. Filled up the tank and put new filter in along with fuel pump, all rubber seals on the tank and so forth.

    #3: Tune Up.
    Plugs where replaced just before I bought it, they used the ones with the 4 ground pins instead of the single one. Don't really like these since checking the spark gap is rather difficult but I drove the truck home with it.
    Wires where done recently also by my judging. Rotor and cap however are for sure the older ones and I have also not yet replaced those.

    #4: Check all the vacuum lines.
    No vacuum line damage, found an open port and plugged that. Also been using that port to put a gauge on the get a vacuum read out.

    #5: Replace the thermostat and clean out the cooling system.
    Thermostat, radiator, radiator cap and fluid all have been replaced. System has also been flushed
    For a car driving in Texas the temperature is staying rather low.

    #6: Go get a fan shroud.
    Either I am a lucky one or this truck was build with the shroud. It is a mechanical fan instead of an electrical that I am more used to but it runs and the clutch engages also, just not sure at what temperature it does or how to test this.

    #7: Check and clean the ground on the ECU.
    Good advice considering all the electrical issues I have found already on this little truck. Something I will have to get to soon.
    Thus to say, I have not done this yet.

    #8: The PCV Valve.
    Shall be cleaned as well. The hose itself is in good shape on the outside.

    #9: The EGR Valve.
    The EGR Valve can cause the engine to run rough at idle and not pass SMOG if you live in a state where you have SMOG. Many times they will plug up and stop working. If they do then it can stick open or closed causing problems.

    #10: MCA Jet Valve.
    Replace the MCA Jet Valve with an elimination kit from RockAuto.com. The Jet valve can burn off the tip or stick open and cause the engine to blow off vacuum lines, back fire, another strange things.
    I have no idea what this is at this time or where to find it, shall research some on this.

    #11: The coil.
    Coil has been replaced along with the plugs.

    #12: The Oils. Engine, Transmission, Rear End, Brake, and Power Steering.
    Oil has been replaced just before I got it, its still "clear" at this time. The break oil I have not done anything with other then check the level. Something I will add to the list.

    #13: Your Belts.
    They need to be done for sure, both the alternator and the AC belt. AC does not work at this time though but the other one is important to get somewhere without the engine over heating or the battery dying on me.

    #14: Front end parts.
    Last owner started work on the front end parts, I should pick up on his work and finish it.

    #15: Fuel lines.
    Work for this has not been started yet but been looking for parts for it. They seem not that easy to come by anymore and I am not ripping these of a junk truck to not have improved on it.

    #16: The battery clamps and wires.
    Battery has been replaced and I have done the clamps and part of the wires also now. Seem to have other electrical issues elsewhere for which I have not yet found its location.

    #17: The Unknown
    As I find them I deal with them, some of them I might need advice for though. Hope I can count on some of you all on here and where I can I shall return the favor.


    I shall follow up with an other post for things that I have done and issues that I have had or still have.

    Thank you for having me.

  2. #2

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    Welcome fushigikaze -- I am the least qualified guy here about these trucks and wish you good luck fixing your truck...

    Fuel & spark..? My truck ran better after I sprayed several shots of carburetor cleaner into the carb (with & without the engine running) it especially helped solving a too rich cold engine problem (dirty choke plate)...

    SPARK PLUG WIRE removal & installation tool is available at NAPA stores (buy it & use it every time you install or remove a spark plug wire)

    Power wash or use compressed air to clean around the spark plugs... THEN

    Try removing the spark plugs ON A COLD ENGINE inspect them for fouling and proper color and proper gap... Black plugs = no spark & white plugs = no fuel...

    Use anti seize and install new OEM recommended spark plugs... The reason for doing this with a COLD ENGINE & anti seize is it will help prevent stripping & crossing the threaded spark plug holes in the cylinder head... Aluminum heads + steel spark plugs = stripped or crossed aluminum threads if done ON A HOT ENGINE...

    NEXT make sure all the spark plug wires, coil & distributor connections are firmly connected & conducting current (use electrical silicone sparingly) because too much can cause misfire and send the electrical current to ground & not the end of the spark plug...

    If FUEL & SPARK are good then CHECK for lack of compression, improper valve or spark timing, plugged exhaust system, bad ECM or emission component malfunction EGR PCV, & vacuum leaks...

    The stock Mikuni carburetor often causes problems many folks here install Weber Carbs... My truck has the stock carb but does have a slight miss half the time...

    That is all I know to try my friend -- best of luck & please post a photo of your truck, thanks

    GET STANDARD SPARK PLUGS..!
    Last edited by xboxrox; 07-12-2019 at 01:04 PM.

  3. #3

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    Hi and welcome to mightyram. One of the biggest issues with these trucks straight up not running is a bad ECU. They are notorious for it and it is also a relatively simple fix. The capacitors in them fail and subsequently the ECU is left inoperable. Normally the fault is visually detectable by opening up the ECU case - the caps will either have leaked and/or swelled up. If you can wield a soldering iron you can handle this. Next is a possible ICM in the distributor. They can also fail (new replacement modules are available). Do things like trying to pull error codes from the ECU, check fuel pressure, spark, injector pulses etc to narrow down what it is (or isn't) doing.
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  4. #4

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    xboxrox thank you for the advice. Mine is a fuel injection so I have no carb issues. I gots a whole boat load of other things that mostly don't work
    The engine is rater for 8.5 compression at, I think 350 rpm. given that atmosphere is about 15 PSI throwing a factor of 8.5 to that comes to just under 130 PSI ( atmosphere PSI X compression = cylinder pressure OR 15 PSI X 8.5 = 127.5 PSI ).
    All cylinders read over 130 PSI with starter motor RPM, which should be around 350. So timing there of the valves looks to be in specs, the timing for the sparks. That be a different thing listed some more below.


    geezer101
    I did some looking around for info about these ECUs. They seem to be the cause of a lot of wrong doings. I pulled mine out yesterday and found out its a "Remanufactured". Plastered along the gap where you separate the 2 covers are a whole store of "Do NOT open, Warranty VOID if tampered or broken seal" warnings.
    Like I really cared at this point and who knows when the work was done and to what quality. So I did it, took the whole thing apart. There solder job looks worse then what I did with them irons when I was 5 years old.... The caps them self's look ok, they have touched a lot more components then just them caps and left some overly big solder blobs on some of the components. Seems I have my work cut out on this little board. When I was about to put if away for now I noticed 2 very clear burned areas on the inside of the lid. Wonder if that is from before or after the rework by my unknown "professional".
    The ICM ( not sure what is stands for but I am assuming the optical sensors for crank location and fuel injection timing in the distributor) I took apart as well when I did the distributor. I have not done any further testings on this at all yet.



    I was able to make a little bit of time this week and yesterday. I got a rather strange situation here.
    I took the distributor assembly off of the engine and cleaned that up. When I took it off and unplugging the spark plug wires, I noticed that they where not wired correctly. Cylinder one is supposed to be on the bottom and with a fire order of 1-3-4-2 3 should have been on the port facing the front of the truck. the #1 plug came out of port #3. All plugs where rotated 90 degree's clockwise.
    Odd if you ask me but this is how I drove the truck home. I did my work on the distributor and had to look around for a while on how ti install this again with the correct timing. Installed the unit again with TDC on #1 and the rotor pointing down. Wired it all back up and gave it a shot ( with plug 1 on distributor port 1 or the one pointing down ). Engine runs about the same as it did just before it would not start again but it is sort of running. Grabbed the timing light and WOW. Its firing halfway through the power stroke. Or was off time. Figured I was off on the installation of the distributor so I pulled if out partially and rotated the rotor to make the gear hit a different tooth. That only made the engine not run at all again. Took the mounting bolt off of the engine so I could rotate the distributor mostly freely. Got it to run, sort of. But I do have to turn the whole distributor assembly ( with TDC1 pointing down as it should) about 30-40 degree's counter clock.
    I seem to still have many fun days ahead.

    Time to put some of my IC and electronic test equipment to use again and pull the optical sensors from the distributor before the sun really starts beating down today here in Texas.

  5. #5

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    The ICM is the 'ignition control module' in the distributor. Judging from what you've uncovered, the ECU is the main culprit (or whoevers' hamfisted effort of repairing it). There is a groundwire in the engine bay that needs to be earthed so the ECU will accept any changes in ignition tune (for those of us who aren't initiated with it, it can catch you out)

    As a side note - I can't say that this will be relevant to you (and you won't know until the ECU and other factors are eliminated) but I ran into a weird problem with a distributor a long time ago that really caught me off guard. After a head swap I couldn't get an engine to run. Set it up 'by the book' and could barely get a cough out of it. Put it forward a tooth and fully retarded the timing - nothing. Put it back a tooth and fully advanced - nada. Somehow the distributor was out by half a tooth which was causing the no run/no start issue. I reinstalled the distributor with the rotor facing the opposite direction and changed the firing order - it fired and idled first shot (after nearly 4 hours of assing around with this thing). If the timing doesn't seem to make sense when you aim a light into there, this might be worth taking into consideration. Good luck!
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  6. #6

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    Your engine a 2.4L <--- I have no experience, my engine 2.6L

    geezer, do you know if 2.4L engines have unique problems..?

    Have you used a timing light on it..? I think RPM must be set & vacuum advance lines removed for timing (OR something like that..?)

    I still think you should get new standard spark plugs & trash the four pin aftermarket plugs...

    You'll figure it out; it's just a matter of time PUN intended

  7. #7

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    Quote Originally Posted by xboxrox View Post
    Your engine a 2.4L <--- I have no experience, my engine 2.6L

    geezer, do you know if 2.4L engines have unique problems..?

    Have you used a timing light on it..? I think RPM must be set & vacuum advance lines removed for timing (OR something like that..?)

    I still think you should get new standard spark plugs & trash the four pin aftermarket plugs...

    You'll figure it out; it's just a matter of time PUN intended
    The only thing I know that can really cause issues are bad ECU's (especially the 1990 model due to it being a unique management system requiring different ancillaries compared to the other injected 2.4 truck engines - members have posted up things indicating it's not a cheap fix and requires this year specific ECU) and the heads warping. I've counted at least 3 members who have posted catastrophic failures where the cams have binded up in the journals so badly the cams have snapped. I don't know of any other Mitsu engine that has exhibited this kind of failure but it has to be related to severe overheating or a sudden change in thermal cycles. The timing in the 2.4 isn't advanced by vacuum due to it being all electronic management.

    This will help with setting the timing for 4G64 engines - http://www.mightyram50.net/vbulletin...th-ECM-control
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  8. #8

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    Thank you for all the information. I have been very low on time to do much at all since last post. Bought a new full distributor assembly ( ICM, rotor, cap, ... ) not yet installed it since I did find some wrong doings on the ECU.
    When I figure out how to add pictures to post I shall do so of both the little truck and the ECU board.
    When I was checking the ECU board in further detail I found 1 missing piece so far, a surface mount cap "C4" it is between diode "D105" and "C105" with the latter being one of the usually bad Rubycon capacitors.
    I know that these types of caps usually do not have information on them but would anyone be able to tell me what cap is supposed to be in this location?
    If worse comes to it I will have to start the hunt for a new ECU.... or really find the time and reverse engineer one somehow.
    The board code is "JE331B993B"
    Having found this missing component I am not really sure if I should try running the engine at all for now.
    Meanwhile I will go make some pictures and order some parts to deal with the bad job done on the board for now. Shall post some images soon ( hopefully ).

    Thanks again everyone :D

  9. #9




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    there is a thread on replacing caps on these boards - search for it. It will tell you the values and placement on the board.
    Pennyman1
    The best Dodge that Dodge never made
    Living the D-50 lifestyle since 1980

  10. #10

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    Thx for the advice, running out of time for now and I have tried the search but so far all I found was about the Rubycon caps or in general the electrolythic ones, not the little SMD ones. Shall give this an other go when I have more time. For now I have to head out and earn my keeps

  11. #11


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    You could be 180* out on your timing. Remember the Crank turns twice for every once the cam does. Reset the timing mark at 0 then put in the distributor rotor at #1. then try and fire it. If #1 and #3 plug wires were reversed the OP missed timed it doing a "Repair"

  12. #12

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    If it where 180 out of time, it would have made total sense, the last owner though had plug for cylinder one in the 9 o'clock position, where spark 3 should be. The rotor was still pointing to 7ish o'clock with that setup. Now that I replaced the ICM ( and everything around it ). I am figuring that this was the "fix" for the bad ICM to still make the truck run. She runs again now and still leaving me with a nice list of other things to tend to.


    I had a little bit of time the last Friday of July to work on my little truck. The new distributor assembly came in also giving me more reasons to to force my schedule and make time to work on it. Installed the new distributor and plugged everything in and "poof". Start and without hesitation, engine running. Slightly out of time but running. Set the timing by feel at that time, timing light I have is not bright enough to beat the Texas sun beaming down. Gave her a test drive and gots power again to pull herself up the hill where I live. Stutters a little so timing is not 100% yet. Drive to work with her all week and on Wednesday I was able to use the garage at work to correct the timing. By feel I had it set to about 3 B-TDC. With the timing light I changed that to 10 and every few rotations its "spiking" for one rotation to about 13-14. Gots way more power now then with the 3 but you can notice that spike when going up hill so I will probably time it to about 7 and see how that runs.
    After having put about 80 miles on her though, she wanted to start no more. Jumped and ran fine. Drove her to work after the jump and put the battery on the booster charger, battery low on charge. Tester the altenator to what extend I can without car shop tools, I work in maintenance for beverage industry so I do have access to all sorts of tools. Yep, altenator not generating any power.
    Thus for over 80 miles now I have been running on the poor car battery, radio and everything else for comfort and need ( lights in the dark, ignition, .... )
    I hope its just worn brushes anthough even if the whole thing has to be replaces, its really easy to get to. Almost everything is easy to get to on this engine. Except for the fuel injectors, have to take the whole intake out for that since they behind the surge tank. Cleaned up contacts and such at work again but had little to no effect, have not been able to find a way to access the bruches yet or even there location. Driving around though, I really miss power steering on these hilly roads

    Last night, again at work, I also made a fix of sorts for a failing fire wall. Either when the clutch cable got replaced they ripped the area around it or the metal is suffering from fategue around there. I saw it was ripped before but last drives I could not get the clutch to disconnect anymore. It is really over due to get the new building for work finished so I can use the tig welder and make a nice support for it.

    Soo much work and nearly 0 time

    I still have yet to figure out how to put pictures in the posts. Also have PC issue with it not wanting to open the files for editing no more and have not even had the time to work on that. Lets go see if the laptop is more willing for the pics and then figure out how to post them on here.

    Thx again for everyones help getting me back on the road-ish :D

  13. #13

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    Wow, ok that was easy. I am not used to just being able to drag and drop them in the text fields on forums.

    Here she is :D
    Black 1992 Mitsubishi Mighty Max in the front ( Mine )
    White 1988 Saab 900 Turbo Convertable In the back. ( Mine )
    Tan 2006 Ford Taurus Mostly daily go everywhere car ( In real need of a lot of maintenance ) ( The wifey's car )