racing 4g64

I recently picked up a 1989 mighty max with a transplant 2.4 EFI from what appears to be a 1991. This truck had been successfully raced for a few years in the mini stock class and a buddy got it in trade, and I'm buying it. currently it does not run (no spark), Ill get digging into that as time permits once the truck is in my garage.

the stock harness is mostly in the truck and my question is, what is the bare minimum to run the engine successfully?
id like to get the harness from the pcm reduced to the minimum wires possible, I know injector wires, temp sensor, oil pressure sensor (?), MAF, ignition/fuel pickup from distributor (optic sensor?).

this truck has the 5 speed manual, its 2wd, and as close to stock as possible per class rules. I can run MSD type aftermarket ignition, but supposed to use factory PCM.

if I swap to mini mod class I can do a 4G63 DOHC head swap and possibly turbo if I want to put that much money into a hobby.

just wondering if anyone has done this type of thing before? I can get all the wiring diagrams, but it would be great if someone already has a list of not needed wires to cut the loom down.

on a side note, if there are any quick checks for ignition related problems (I swapped the ICM to no avail, and am going to pull the PCM out and open it up within the next week to check for blown Caps).

Thanks much, I'm learning lots on this forum.

-Brent

Welcome to the forum. :)

If you can post an image of your truck, go for it.

And yes some here have made changes just like you have asked. I'm sure they will chime in sometime and let you know. Meanwhile, familiarize yourself with our forum if you like.

Thanks for the Welcome.
ive been reading all I can on this little truck, as my daily mechanic experience is a bit different (modern computer controlled diesel)... but ill get the feel of this gasoline stuff soon enough... I just cant get past the need of spark plugs, just bump up the compression already... lol

You may see if you can PM maybe droppedmitsu here in the forum. He is a wizard with the efi dohc engine and may have the answers you need. He also swapped his motor for the engine your asking about.

Bare minimum for the 4g64 to run you will need: ECU, Main Relay(gold box next to ECU), Idle speed controller motor, power transistor(powers the coils, etc), ignition coil, distributor, motor speed sensor(its combined with another sensor or electrical item that's needed but cant remember which one), throttle position sensor, idle switch, engine coolant temp sensor, o2 sensor, Mass air flow sensor. There's also a few check connectors(fuel pump check connector, and also Ignition timing adjustment connector) that you will want to keep also. If you look in the manuals section we have tons of manuals and you can figure out which connector/plug/sensor is which, also here: http://mmeierle.com/MPI24LCircuit-1.jpeg

I think that's it, I will double check my list when I get home from work in a few hours in case I forgot anything.

Quote:

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Originally Posted by DroppedMitsu

Bare minimum for the 4g64 to run you will need: ECU, Main Relay(gold box next to ECU), Idle speed controller motor, power transistor(powers the coils, etc), ignition coil, distributor, motor speed sensor(its combined with another sensor or electrical item that's needed but cant remember which one), throttle position sensor, idle switch, engine coolant temp sensor, o2 sensor, Mass air flow sensor. There's also a few check connectors(fuel pump check connector, and also Ignition timing adjustment connector) that you will want to keep also. If you look in the manuals section we have tons of manuals and you can figure out which connector/plug/sensor is which, also here: http://mmeierle.com/MPI24LCircuit-1.jpeg

I think that's it, I will double check my list when I get home from work in a few hours in case I forgot anything.

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Thanks for the info. That's about what I figured, now I gotta print out a pin out of the pcm. Should have the truck at my house early next week.

Wiring diagrams and additional engine info available here.

http://www.mmeierle.com/mighty%20max%20info.htm

I have converted a 4g64 to full on racing with Turbo, converted the ECU to a aftermarket AEM unit, and deleted the Distributor and changed to a dual coil setup to look like a Turbo 2.0 engine.. wanna buy it? as in the entire truck...:-)

http://www.mmeierle.com/turbo_build.htm

I can probably give you some pointers...

Wish I could, but half the fun of this truck is the project. I'd appreciate any tips and tricks as I run into problems. Thanks for the info for wiring diagrams.

I understand, a majority of the fun of racing is getting there...

Quick update, found a whole list of things wrong, slowly getting them corrected.
1) bad connection to ignition coil (the weather pack plug about 3 inches from the coil) no connection.
2) blown cap on pcm circuit board (1.49 at radio shack)
3) bad wiring repairs all over (oxidised butt connectors especially on cam sensor harness)
4) cap and rotor (because old ones looked terrible)

Now it idles great, but won't rev past 2000. Like its hitting a rev limiter, picks up fine, then drops out till it gets to 1200 or so, then picks up again. Even At WOT, just bounces.

Any thoughts on this?

Thanks much

try replacing the other caps in the ECM - if one is bad the rest are not far behind. Also check the tps sensor - it may be out of adjustment.

Quote:

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Originally Posted by pennyman1

try replacing the other caps in the ECM - if one is bad the rest are not far behind. Also check the tps sensor - it may be out of adjustment.

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Do you have info on how to set the tps? Also, I read the maf may be too blame, but again, in unsure how to test.

lots of info here...http://www.vfaq.com/index-main.html

also the Tech section has all the manuals

http://www.mightyram50.net/vbulletin...er-Source-Info

yes replace all the caps...

Cool. Thanks for the info, guess I'll be heading back to radio shack for more Caps, I only bought for the one leaking.

Pulling my hair out... Had it running, though it would only rev to 2000 rpm. Swapped out the other 2 electrolyte caps, pulled off the cap and saw the rotor was cracked (guess I didn't seat it fully), replaced it.
Now it's acting like the timing is 180 off, it's simply belching fire out the exhaust... I'm sure it's something simple, but very frustrating. I'll mess with it more tomorrow. For now, I guess I'll research the wiring diagrams.

This little truck will run yet...

You are assuming the motor was still working when you bought it. The problems you are having are why the person sold it. Take the timing cover off and go through the setup as if you just changed the timing belts - this will eliminate a misinstalled timing belt. Check the threads for the proper timing belt install setup - the factory manual method puts it on 1 tooth off.

Quote:

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Originally Posted by pennyman1

You are assuming the motor was still working when you bought it. The problems you are having are why the person sold it. Take the timing cover off and go through the setup as if you just changed the timing belts - this will eliminate a misinstalled timing belt. Check the threads for the proper timing belt install setup - the factory manual method puts it on 1 tooth off.

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I've double checked the timing belt per the instructions on the site. All is good there.
It was running this morning before I soldered in the new caps and changed the rotor. I checked the rotor, only goes on one way, I've double and triple checked the plug wire order, it's 1,3,4,2, with #1 being bottom left of the cap (correct?).

Back story, the truck was running fine in a race, then died (no spark) previous owner changed the coil, still no spark. I found the damaged connector and replaced the connector with a hard soldered wire.

I then opened the pcm, found one of the capacitors was leaking out. I removed the bad cap, cleaned the board, inspected the traces, soldered in a new cap, so was fine. Truck ran.
By recommendation of members here, I reopened the pcm to replace the other 2 electrolyte capacitors on the board. Same procedure as before, reinstalled the pcm. Now timing acts like its 180 out. I rechecked cam timing, looks good.

I also reset the throttle position sensor to .499V. Spec is .48-.52V.

I'm sure it's a simple fix (probably something I did caused it) but I'm not sure where to look. I don't think my soldering was no good, but I'll pull the pcm again and double check...

Be sure you clean the board good after soldering - sometimes flux splatter can cause high resistance shorts. Also be sure the polarity of the caps are correct.

Just pulled the pcm again. Rechecked, recleaned, reinstalled, no dice... Oh well, I'll continue pulling my hair out tomorrow afternoon. Getting dark already.

Thanks for the replies.

Ok. Got it running again. Not sure how, but I bumped timing 180 out... Or it was like that and I put it how it was supposed to be. Either way, back to running.

My main issue now is it still will not rev past 2000 or so, and acts like its bumping a rev limiter. MAF? Pcm? Any quick checks before I spend more money this weekend?

Thanks everyone for your knowledge and patience

Well, I've made a bit of head way on my project. The truck is now running very well, though only when the pin is grounded to set base timing, when operating under normal circumstances it pops, misfires, and has a terrible idle.

Thinking it may still be pcm related, or at least bad wiring connections.

I've ordered a fuel cell and pump, I need to find a regulator to plumb inline before the factory regulator to keep from flooding the cylinders from higher than normal pressure.

I've plugged and disconnected the vacuum lines to the egr (couldn't believe it's still on the truck) and I'll make a block off plate when I'm back to work.

I've discovered the alternator is junk.

I've also found that the PO seemed to have glued the mechanical fan onto the water pump, I'm going to replace with an electric setup.

The factory exhaust was cut off at the flange before the 2-1 so I have to fabricate up a new 2-1 collector and pipe instead of the manifold dumping on the frame rail.

I'll get a photo bucket setup with the build and what not.

I'll be replacing the roll cage in the next couple weeks, then I'll be able to dive into wiring the truck how I want it done.

I guess that is all for now.

Always fun undoing some monkeys' handiwork. And it nearly always leaves you scratching you head on on what the hell they were thinking when they were 'fixing' something. Seems like you're very close to getting the truck running right. It will be worth it when you can finally hit the road. :thumbup:

Quote:

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Originally Posted by geezer101

Always fun undoing some monkeys' handiwork. And it nearly always leaves you scratching you head on on what the hell they were thinking when they were 'fixing' something. Seems like you're very close to getting the truck running right. It will be worth it when you can finally hit the road. :thumbup:

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No road to hit with this one. Only the track. Hope to have it up and ready by mid February for the opening race.

Could it be the module in distributor or loose connection? Just a thought about when mine did the same thing of running great and then...WTF?

Can't wait until you find the problem and kick yourself over and over why you didn't see it, LOL I have a boot in my ass permanently:lmao: because of this.

Quote:

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Originally Posted by BradMph

Could it be the module in distributor or loose connection? Just a thought about when mine did the same thing of running great and then...WTF?

Can't wait until you find the problem and kick yourself over and over why you didn't see it, LOL I have a boot in my ass permanently:lmao: because of this.

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Haha,
Yep, I'm sure it's something simple. After I get the new cage welded in I'll start the process of gutting the stock harness and rewire to the bare minimum. Seems like every 5 minutes I'm on eBay, jegs, summit, speedway motors ordering more stuff. Or running to autozone for local stuff.

This racing stuff gets expensive quick, and I'm in the cheep league.