Engine swap no start 95 mighty max 2.4 sohc

[95mightymax?]

1995 Mitsubishi mighty max
Engine: 2.4 4g64
mileage: unknown
mods: lowered on block and springs all new Jeff’s suspension aftermarket steering wheel and shift knob

here’s the run down I bought this truck a little over a month ago not running the guy said he had replaced distributor, spark plug wires, and spark plugs trying to fix it I bought it for 800$ and trailered it home once I got it home I started trying to diagnose the problems I started with spark it had spark, had fuel timing looked to be correct i then did a compression test and found that there was 0 compression in all 4 cylinders removed the head to find terrible scratch marks down the bore and rust so I decided it was time to get a new motor i started by disassembling the head and lapping the valves and replacing the valve stem seals and I got a bottom end from a 92 mighty max at my junkyard for 300 bucks with a 90 day warrany the motor looked great had crosshatching on the cylinder wall very miles carbon buildup on the head but I only took the bottom end any way so I swap the motor everything went smooth there pulled the old one out put the new one in and I went to start it and nothing just turned over, so I started diagnostics and there is spark and fuel and compression so it leaves timing I hear a cylinder combust every so often not with any pattern or anything like that but it combusting I just don’t know where to start I had the crank lined up at tdc with cylinder one up and I have the oil pump and balance shaft lined up I know I have the oil pump balance shaft in the correct orientation from working on my eclipse so I believe it’s in the cam timing when I have it at tdc and the cam gear lines up I can’t get the distributor to stay lined up with the little dimple and line on the end of the distributor I’m pretty stumped here I can’t wait to rip it down the road just have to figure this out any suggestions are appreciated

[geezer101]

Hi and welcome to mightyram. Bunch of things could be wrong. You've worked on an Eclipse so you know your way around fuel pressure and coils etc. DSM's are getting old and they have their fair share of electrical issues. The Mighty Max is notorious for bad ECU's - it's the brand/type of capacitors that were used in them and they are prone to leaking. Crack the ECU open and look for telltale signs of swollen capacitors and leaking/stains on the circuit board in the proximity of the capacitors. Just google "faulty capacitors in Mighty Max ECU's" and you will find that the first images trace back to this site. PDF is here

[95mightymax?]

Hi so I tore the Ecu out and after inspecting the circuit board I’ve notice a crusty yellowish film along the edges of the circuit board and around the capacitors just wondering if there’s a way to clean it or see if it’s still good and this is actually my issue.

[95mightymax?]

[finalfighter]

do you have a picture of it?

[SubGothius]

See photo post above, was caught in auto-moderation filter, just approved it now.

[geezer101]

The staining would indicate the caps have leaked. Luckily it hasn't eaten into the board yet...

[95mightymax?]

Okay so since that doesn’t seem to be the issue I spoke with the guy I bought it from and he said he had done a head gasket on it and got the head decked so I was wondering if it’s possible that could be throwing off my timing because I noticed I had my timing mark aligned with the top of the head where the valve cover met and that’s when I heard the cylinders at least start combusting but once I moved it to the actual timing mark it is acting like it’s not getting spark

[dash]

when motors sit for long, I always 'pulse' injectors with a pigtail/12V
some you won't hear click. Tapping on injector body, while pulsing 12V..... often revive 'em.
cuts down cranking time tremendously, from my experience

even when my mitsu 2.4 sits for 4+ weeks, ONLY if I remove the brake booster vacuum hose(going to the intake)....
I pour 2 caps of gas in the hose, then blow it thru. Wierd, I know, but fires right up, everytime!

[dash]

I forgot to ask, if you see fuel on the spark plus, or did you crack the feed line to check
If the plugs are wet, obviously injectors work.... so above mentioned procedure won't help

[95mightymax?]

Yes the plugs are wet with fuel I’ve run through all the diagnostics of checking for spark fuel compression and timing at first I thought it was a bad ground for the distributor because of the Intermittent combustion but it has a good ground and I have crank and cam signal all the timing marks like up the distributor dot is on the little peg on the distributor and it points to number one wire it has a good spark it just doesn’t even try to start it’ll just turn over I believe it is a timing issue but I don’t know where to begin trying to figure that out

[geezer101]

All you can do is turn the crank to TDC #1 @ zero, pull the top half of the timing cover off and see where the cam alignment marks are, then check to see where the rotor button in the distributor is aiming. The PO may have screwed the timing up and/or the belt may be off a tooth or 2. The staining on the PCB in the computer is a worry and I would see what error codes it's throwing. When the ECU goes bad it can put the truck into limp home mode or kill off input/output signals that should be triggering events (injector pulses, ignition firing etc)

[95mightymax?]

LSince I’m still getting spark and fuel wouldn’t that mean that the Ecu would be working? And if all the timing marks line up would that mean I just need to fiddle with it to find when it could catch the spark or I’m just stumped here because I can’t see what it’s missing?

[tortron]

Not necessarily, could be very weak or untimed/intermittent spark.
An occasional cylinder catching sounds to me like the timing however. I wonder if the distributor shaft is in 180 degrees out? Maybe the plug wires are going to the wrong plugs?

Valve clearances is another one that shows up as that problem, double check they are opening and closing fully.

A bit of starter fluid here would be useful, even if everything is unhappy it should catch on that, and then you will be able to tell if its timing is irratic or if it runs smoothly that its the fuel doing something weird


I had a good one on a bike the other day. Was running but a torn intake boot, so parked up till a replacement came in. Then wouldn't start. Plenty of fuel and spark. Eventually gave in and pulled the head and cylinder to find a tiny bit of carbon sticking the rings in the lands, somehow getting in there after the final run lol

[geezer101]

LSince I’m still getting spark and fuel wouldn’t that mean that the Ecu would be working? And if all the timing marks line up would that mean I just need to fiddle with it to find when it could catch the spark or I’m just stumped here because I can’t see what it’s missing?

Nope. A bad ECU can throw ignition and injector pulses out of sync or make them so weak and erratic it won't fire properly. As tortron has commented, if the coil is bad it will have firing issues too but I think it would fire and idle but not be happy under load/throttle if everything was as it should be. ECU's are not that hard to patch up so you can take a gamble and buy a new coil to see if that fixes the issue first, then move onto the ECU repair. Try to pull codes from it and be aware that the ECU needs to go into tune/diagnostic mode to accept any changes to ignition timing adjustments (there is a single wire in the engine bay that has to be ground to the body to perform a tune up)

[95mightymax?]

since the replacement of the ecu i continued to have the same issue i went to the local autozone and got a compression tester and preformed a compression test and cylinder 1 is at 90 psi cylinder 2 is at 40 psi, cylinder 3 is at 35 psi and cylinder 4 is at 60 so my first thought was a blown head gasket but that wouldnt explain how the number 4 cylinder is at 60 psi is there a way i can test to see if the bottom end i got is bad or it is infact the headgasket

[d50Lewis]

with 90 psi being the most compression I think you found the problem. I have a PCM for a 95 2.4 mighty max that is good if that turns out to be a problem too.

[geezer101]

With compression figures that low you either have a bad head gasket, bad valves and seats, valve timing is way out, worn rings and cylinder bores - or a combo of the aforementioned.