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Voltage Effected Rough Idle

Specter

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Joined
Apr 20, 2008
Messages
367
Location
Karachi, Pakistan
Okay so, my idle has been very rough lately. Ignoring the problem i used the car as usual until today when it started to bog down even at 1500rpm. I also noticed that, when i turn the parking lights on, the rpm goes down from 1000 to around 800, idle gets rough, when i turn the headlights on it goes down to 600, at this point the idle is very rough, i turn the ac on and car dies.
I then checked the pins in ecu which are 12v power related. Turns out that (EVO III ECU 72 PINS) :
PIN 60 : 12V Battery Power Supply (constant) has no current in it.
PIN 62 : Main relay 12v IGN Start Key Supply has 10volts at idle, drops down to 9.5volts when i turn the parking lights on, drops down to 8.5 volts when i turn the headlights on, and goes below 8 volts when i turn the ac on just seconds before the car dies.
I have yet to check these PIN's:
Pin 12 : 12v Switched Power Supply from main relay,
Pin 25 : 12v Switched Power Supply.
I am assuming that i tracked the cause of the problem, i would like to know,
1) How much volts should PIN 62 see? Does it get its feed from the ignition switch?
2) Should i connect the PIN 60 (constant battery power supply) to the battery? What is the purpose of this PIN?

Its a bit long read, i hope you guys understand what my problem is.
Thanks!
 

curtis

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May 4, 2003
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11,892
Location
Clarksville TN
Sounds like you have an alternator dying a painful death or just the voltage regulator in the alternator. Replace the alternator and while your at it run an extra or larger gauge wire from the alternator to the fuse block on the battery, while your at it a larger wire from the battery to the starter and a bunch of large gauge wires for the grounds, There is always ground blocks with wires on ebay. They really do help.
 

toybreaker

iconoclast
Joined
Apr 30, 2006
Messages
3,581


The "o" voltage you found at a few feed points suggests a blown fuse, so before you do much of anything, I would check for power at the connection on the back of the alternator.

Then I would check all the fuses at the battery cable, and the alternator fuse in the front fuse box, (as well as the other big fuses there.)
 

Specter

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Apr 20, 2008
Messages
367
Location
Karachi, Pakistan
Sir i checked all the fuses, and also check the alternator output, the alternator is throwing around 14.5 volts, and the fuses are fine also. I know i had some hacked up ecu wiring, but i did not know how much until today.
From what i understand, the MPI Relay has two pins, one is powered from the battery while the other is powered from the ignition switch. Same ways the ecu also has one pin which gets current from the battery, and the another pin gets its current from the ignition switch. As i said earlier, my PIN 60 ( constant battery power ) is at 0volts. While Pin 62 (ignition power) and two pins of the mpi relay have " the same wire feeding all of them ". Yes one wire is split in to all three of these pins. And that one wire is coming from my 3 pin connector of the coil pack, and that coil pack is fed by the 8 pin ignitor. So the way i see it, my ignitor is feeding the coil pack, Pin 62 of ecu, and the mpi relay. Ouch!!! Considering that, my transistor is now dieing as it is the source of all the voltage for my ecu and mpi relay.
After reading many topics on this forum, i look forward to first, correct the wiring, then try to run the car. If the situation is same, then i would change the ignitor too. That should solve the problems.
Before i start it, i would like to know where to feed the Ignition Switch 12v Pins of the ecu and the mpi relay. Should i look for a power source from the fuse box near the pedals?
And for the Constant Battery Power Pin of the ecu and mpi relay, i would have to take the wires to the under hood fuse box attach them to their individual fuses (20A for mpi relay and what value fuse for the ecu?) and connect that to the battery. Am i on the right track till now?
Thanks!
 

toybreaker

iconoclast
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Apr 30, 2006
Messages
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Nice posts, it's a pleasure to help someone who puts such detail into their questions! /ubbthreads/images/graemlins/smile.gif

Sadly, I do not have a wiring diagram for an evo III ecu, so I can only give general advice, based on my experience with other mitsubishi models of that era.

At any rate, the purpose of the mpi relay is to switch the current for the high demand items on and off so the ecu doesn't have to see those loads.

Understanding that, all we have to do is figure out which of the pins of the ecu are switchers, and which are switched, and then we can put things back the way they were when the car left the factory.

If you could post a wiring diagram, I can help you figure out what goes where, and in what order.
 

Specter

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Joined
Apr 20, 2008
Messages
367
Location
Karachi, Pakistan
Thanks for appreciating /ubbthreads/images/graemlins/smile.gif. I have been trying to search a wiring diagram since last 3-4 hours, but all i could find out was the ecu pin out diagram. It is a PDF file and i do not know how to link it here so i am typing the MPI relay related Pin outs of the ecu. It would only take a minute to search the diagram and find this but i am posting it here. The description used is as per the diagram. I'll explain what goes where in my car and how *i think* it is supposed to be from factory.
Pin 08: Fuel Pump Relay (MFI Relay Power Supply)
Pin 12: 12v switched power supply from main relay
Pin 25: 12v switched power supply
Pin 38: Ecu main relay activated by Pin#62
Pin 60: 12v battery backup power supply (constant)
Pin 62: 12v IGN Start Key SW Supply.

I am assuming that like Pin 12, Pin 25 power supply also comes from the relay, and as much as i can remember so it does in my car (un-hacked). Pin 38 also comes/goes to the mpi relay (un-hacked). I guess no problems here unless you think otherwise.
Now the hacked wiring part is Pin 62. The feed for this Pin is coming from the 12v feed of the Coil Pack which comes from the Ignitor and not connected to the ignition switch. Pin 60 has no current in it. It is used so that ecu can store memory of the most recent settings done (if any). My ecu resets every time i start the car because it cannot store any memory, no harm here i guess but its not how it was meant to work.
This was the ecu part. Now we come to the Mpi relay part. My Mpi relay is a 8 pin relay. It is one of those twin relay which controls both fuel and ecu output. Out of the 8 pins, there are 2 pins on it, Pin No.4 and Pin No.8 ( black wire with yellow stripe). Both of these pins are connected to the same wire feeding the Pin 62. One of them SHOULD be (i think) be fed from ignition switch (like Pin 62 on the ecu) and the other should be fed through a fused line from the battery (like Pin 60 on the ecu). By doing so, my ecu and the mpi relay would get better voltages, and my Coil Pack would get its feed straight from the Ignitor with no intervening wires.
I am sure you know all the stuff i just explained to you, but i just did it so you know what my understanding is of the system. I tried to be as crystal clear as possible.
Thanks for reading! /ubbthreads/images/graemlins/grin.gif
 

toybreaker

iconoclast
Joined
Apr 30, 2006
Messages
3,581
Edit

Got pin out to load.





Now we can be on the same page. /ubbthreads/images/graemlins/smile.gif

I'm searching for the actual engine wiring diagram now.

Any help from the computer/search saavy guys would be appreciated.


 
Last edited:

toybreaker

iconoclast
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Apr 30, 2006
Messages
3,581
Quoting Specter:
Thanks for appreciating /ubbthreads/images/graemlins/smile.gif.



No worries, love a good challenge. /ubbthreads/images/graemlins/smile.gif


Pin 08: Fuel Pump Relay (MFI Relay Power Supply) White/Red



This is the wire that the ecu pulls to ground to authorise the fuel pump.

It should be noted that on a 2g mfi relay there is only one fuel pump coil.

This means the ecu controls the fuel pump relay coil (and therefore the fuel pump) in all aspects of engine operation, including the start cycle.

The same strategy is used:
Pump "on" anytime the engine is cranking over on the starter
Pump "on" anytime the cas is sending a signal
Pump "off" anytime the cas signal is interupted, or the engine isn't turning over

I mention this only because the usdm vr-4's/1g models had a second, hardwired coil on the fuel pump circuit, and it turned the pump on as a seperate operation, independant of the ecu, so any information you find on the board won't pertain to your car.

Pin 12: 12v switched power supply from main relay Red

Pin 25: 12v switched power supply Red

I am assuming that like Pin 12, Pin 25 power supply also comes from the relay, and as much as i can remember so it does in my car (un-hacked).

Looks like those are both switched power out of the mfi relay, if they haven't been molested .

There appears to be two outlet terminals on this circuit of the mfi relay, terminals 2 & 3.

Terminal 2 (red wire) of the mfi relay is used to provide power out in the engine compartment

Our 2g's use a different color wire, (Black/Red) out of the relay on terminal 3, but then there's a three way splice where they all change to solid red. Two legs feeds the ecu, (terminals 12 & 25 ) and the other legs head out into the engine compartment

This is where the diagram would really be nice, as it would have the splice location....




Pin 38: Ecu main relay activated by Pin#62 Black/Blue

Pin 38 also comes/goes to the mpi relay (un-hacked). I guess no problems here unless you think otherwise.



Kinda sh*t out of luck on this one. /ubbthreads/images/graemlins/frown.gif

Usdm models are using a Blue/Green wire out of ecu terminal 38 to mfi relay terminal 6 to authorise the ecu/engine feed relay coil.

If this is anything like the usdm market ecu/relay system, just the simple act of having 12v applied to the ecu on pin 62 tells the ecu to pull ecu38 to ground, which turns on terminals 2 &3 of the mfi relay.

don't take that as gospel, tho... that's just a w.a.g (wild ass guess /ubbthreads/images/graemlins/wink.gif )

Pin 60: 12v battery backup power supply (constant) Black/Yellow

Pin 60 has no current in it. It is used so that ecu can store memory of the most recent settings done (if any). My ecu resets every time i start the car because it cannot store any memory, no harm here i guess but its not how it was meant to work.




This wire should definately be powered all the time.

Check, check and recheck all the fuses in all the boxes.

Some of the bigger ones are a pain in the ass to check, but you sound resourcefull, so please do that before continuing to troubleshoot things.

The ecu "keep alive" memory is lost everytime power is interupted in this circuit. This means fuel trims and long term octane/timing adjustments are lost, and you are starting from scratch everytime you light the car up.

If you don't find a problem on the supply side, a wire from a constant power source can be run over to it, but I don't like to do that. It can make for a confusing troubleshooting proccess in the future. It's best to return things to the way it left the factory.

Pin 62: 12v IGN Start Key SW Supply. Black/White

On usdm cars, this is the switched power feed from the key, and is energised anytime the key is in the run or start position.

My 2g diagram shows this feeding pin82 of the ecu. Since you only have 72 pins, that's a problem... /ubbthreads/images/graemlins/rofl.gif

At anyrate, it should be hot with the key in run/start

Quoting Spector (from earlier post):
While Pin 62 (ignition power) and two pins of the mpi relay have " the same wire feeding all of them ". Yes one wire is split in to all three of these pins. And that one wire is coming from my 3 pin connector of the coil pack, and that coil pack is fed by the 8 pin ignitor. So the way i see it, my ignitor is feeding the coil pack, Pin 62 of ecu, and the mpi relay. Ouch!!!



This is one area we must be carefull in making assumptions!

The factory used the black/white wire (and in your case, Red) color scheme on many different wires to power up pretty much anything engine related. That can lead to some confusion as to the origin/source of the power on the various black/white (and Red) wires running hither and yon about the engine bay.

Some of them may come straight from the key (not thru the mfi relay) and some of them may have their power controlled by the ecu, via the mfi relay.

A valid test for who's who would be to key the car up with the mfi relay unplugged. You should see power on the black/white input wire, (coming from the key) and quite possibily, nobody home on the other black/white (and/or red) wires.

Plug the mfi relay in, and check the others now.

Did they power up when you turned the key to the run position?

That shows they are relay controlled.

Now the hacked wiring part is Pin 62. The feed for this Pin is coming from the 12v feed of the Coil Pack which comes from the Ignitor and not connected to the ignition switch.

There's probably a splice in there somewhere, and they all originate from the key.

Need a diagram to know for sure, so I'll just stop there.

Now we come to the Mpi relay part. My Mpi relay is a 8 pin relay. It is one of those twin relay which controls both fuel and ecu output. Out of the 8 pins, there are 2 pins on it, Pin No.4 and Pin No.8 ( black wire with yellow stripe).

Carefull!

On the usdm cars, Mits used this wire color combo for both constant 12v (battery) and the starter circuit. (musta had a sale on black/yellow wire. /ubbthreads/images/graemlins/banghead.gif )

Of course, the usdm market cars use a different color wire on the 2g mfi relay, so we're lost there. /ubbthreads/images/graemlins/frown.gif

Pin 4 of the mfi relay appears to be the main power supply into the relay for the ecu and other engine related components.

Pin 8 at the mfi relay appears to be just powering the relay coil itself.

Both of these pins are connected to the same wire feeding the Pin 62. One of them SHOULD be (i think) be fed from ignition switch (like Pin 62 on the ecu) and the other should be fed through a fused line from the battery (like Pin 60 on the ecu). By doing so, my ecu and the mpi relay would get better voltages, and my Coil Pack would get its feed straight from the Ignitor with no intervening wires.

I've gotta go, and this is as far as I got.

Let's not jump the gun on changing stuff.

The factory usually does a pretty decent job sussing these things out, and we change things at our own risk.

I'll check back in later, and hopefully, someone will have found a wiring diagram for us

Quote:

I am sure you know all the stuff i just explained to you, but i just did it so you know what my understanding is of the system. I tried to be as crystal clear as possible.



The more you can tell us, the better /ubbthreads/images/graemlins/smile.gif

In parting, I think it's important to figure out what's going on with your power supplies, but I think it's very possible your rough idle problem may be lurking somewhere else.

Unhacking things is always a good start, so we'll do that first, but then I think a simple, logical approach would be better suited to finding the rest of the problem.

Plugs, wires, fuel filters, vaccuum/boost leaks and the like... yea, gonna have to check it all...

Cars, gotta love 'em! /ubbthreads/images/graemlins/rofl.gif
 
Last edited:

Specter

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Apr 20, 2008
Messages
367
Location
Karachi, Pakistan
Its good to know big brother, we pretty much think alike, and so far are on the same page. After reading those diagrams which Rich provided (Thanks again Rich!) i went to my car and began the hunt. Something clicked in my mind and i remembered that my ecu CEL turns on the ignition switch, so this means that i do have ignition current. I spliced the Pin#62 this time pretty good, the current was at 8.5v. I started to pull all the taping apart from all my ecu wiring. It ended up like this.


img.php


I traced all the black and white connections coming to Pin#62. I wanted to see where is this ignition current coming from. So i cut the all the black/white wires coming to Pin#62 from the engine bay, rechecked the ignition current and it was still there, therefore the source was near the ecu. After a lot of looking i found it hiding behind the dash near the blower motor.

img.php


Removed the black tape over that joint and separated the ignition power wire from the main harness.

img.php


I then hardly fit my hand further behind the dashboard until what felt like another joint, i removed the tape only with two fingers and found a wire going some where up towards the dash. Took the glove box out and voila i found the source of my ignition current. Its a black/white wire coming somewhere from the dash wiring, i cut it there n then, rechecked the current on those hacked Pin#62 wiring and no more current. Current Source found!

One amazing thing is, i started it when the ignition current at that wire was 8.5v, after removing all the extra harness, the source wire (which is still giving power to the dash clock and other stuff) is at 11.25v! My battery as she sits is at 12.25v, so that is now only 1 volt less then the battery and way above where we started it.

Tomorrow i will hopefully find where is that in dash ignition wiring coming from.

Here is a diagram of how hacked up the system was.

 

Specter

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Joined
Apr 20, 2008
Messages
367
Location
Karachi, Pakistan
I think we can now go step by step and start to correct the issues. First thing first i would like to properly wire my power transistor, the coil pack and where that wire goes. According to the diagram Rich provided it should be something like this :
 

Specter

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Apr 20, 2008
Messages
367
Location
Karachi, Pakistan
I am unable to upload the diagram, i guess the soul of the forum did not like my MS Paint drawing /ubbthreads/images/graemlins/tongue.gif All i wanted to show was that the black/white wire from Pin#6 in the power transistor should go to Pin#3 of the coil pack with another tap going into the Pin#7 of the mpi relay. I do not have any knowledge of Pin#7 of the relay, but the lancer diagram posted by Rich shows the this same path. Even my wiring has an original "two wire in to one" clip in the coil to transistor wiring suggesting that they will go at one place together.
 

toybreaker

iconoclast
Joined
Apr 30, 2006
Messages
3,581




This doesn't look right.

The reason a relay is used in the first place is to cut down on the hotel load that the key "sees".

When the ecu terminal 62 "sees" the key powering up in the run position, it will pull ecu terminal #38 to ground. This wire runs to mpi relay terminal 6. A completed circuit here energises the coil in the mpi relay. The magnetic field created is what closes the relay contacts. That will connect terminal 4 to terminals 2 and 3.

All good so far?

(I must apologise here, My eyesight is not so good anymore, and I'm having a hard time reading the diagrams. /ubbthreads/images/graemlins/frown.gif )

As near as I can tell, mpi terminal 4 should be fed directly from the battery. (not the key.)

According to your diagram, it looks like that circuit has been tampered with, and is now being fed from the key...

Please check mpi relay terminal 4 for power with the key off. It should be live (12v) all the time, as the diagram shows it being fed directly from the battery via sub fuse link 3 (big fuse in the engine compartment)

To verify it has been hacked, first check for power key off.

Should show battery voltage all the time

A valid test for the correct operation of the mpi relay would be to unplug the ecu, and with the key off ground mpi relay terminal 6

The relay should "click", and there will now be power on mpi relay terminals 2 and 3.

If that doesn't work, key the car up to the run position and try again.

If it works now, you have found the problem.

Somebody has bodged the battery feed, and made it go to the key.

That is probably too much load for the key/wiring, and there will be a metric sh*t ton of voltage drop. This will also shorten the life of the electrical contacts inside the ignition switch considerably.

To correct this, start checking the harness in the engine compartment. I would start at the fusible link, and work downstream from there. One area I have seen problems is in the harness run under the radiator. For some reason the factory ran this harness section in split tubing, and left the section untaped. Rocks, gravel and other debris can get in the opening and chafe the harness, breaking individual wires.

This makes for some interesting problems to troubleshoot. /ubbthreads/images/graemlins/crazy.gif

(It should be noted that this on a usdm vr-4, I have never worked on an evoIII, as we never got those here in the states, you harness routing may vary /ubbthreads/images/graemlins/wink.gif )

So, in summary, lets start there.

If I'm reading the diagram correctly, Mpi relay terminal 4 is fed directly from the battery thru a subfusible link.

If it's being fed from the key, that's too much load for the circuit, and the voltage will sag.

edit Another place to look for issues is at the ignition switch harness. There may be a turbo timer, gauges or some whiz bang device tapped in there, and the wires may be tampered with at that location.

Good luck, and keep us posted on your progress! /ubbthreads/images/graemlins/smile.gif

Rich, thanks again for the diagrams! /ubbthreads/images/graemlins/worthy.gif
 

Specter

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Joined
Apr 20, 2008
Messages
367
Location
Karachi, Pakistan
" This doesn't look right. "
=> Agreed! That's why i started the topic because i knew the wiring is not done right.


"(I must apologise here, My eyesight is not so good anymore, and I'm having a hard time reading the diagrams. )"
=> Eat some almonds daily, carrot too, and eggs if you can, also get some rose water if you guys have it there and pour few drips in your eye ( make sure its rose water ) they help a lot, i do not know how much knowledge you guys have about health related stuff in the west, but around here its possible to almost fix anything without a doctor /ubbthreads/images/graemlins/tongue.gif


"As near as I can tell, mpi terminal 4 should be fed directly from the battery. (not the key.)"
=> Agreed again! BUT the diagram shows that terminal 4 and terminal 8 are joined together and connected to the battery through a fuse able link. But it also shows that terminal 4 turns on/off the power to the ecu through pin 12 & 25. This means that it will be powered all the time and hence the ecu pin 12 and 25 too? I think terminal 4 should be connected to the ignition? Not sure!


"Please check mpi relay terminal 4 for power with the key off. It should be live (12v) all the time, as the diagram shows it being fed directly from the battery via sub fuse link 3 (big fuse in the engine compartment)"
=> The funky diagram i posted is what it is in the car. I do not have any sort of battery power in my ecu wiring harness. This is because my engine was swapped and there has been no connection made with the big fuse in the under hood fuse box neither any wire tapped for a battery connection anywhere, so i would need to lay down a new wire to the fuse able link, do not know how to connect on that big fuse yet.


"Another place to look for issues is at the ignition switch harness. There may be a turbo timer, gauges or some whiz bang device tapped in there, and the wires may be tampered with at that location."
=> I just have an after market theft alarm tapped in the ignition system, the gauges i tapped in the fuse box my self, not tampering any wires. Yes any tampering done in the past would be present there, so i will look towards it.

"So, in summary, lets start there."
Lets start here, if you could confirm me :
1) Powering terminal 4 of relay from fuse able link or from the ignition?
2) How to connect a wire on that fuse able link? Do i need to get the whole fuse box out in order to connect the wire to the fuse? I would check if there is a wire present in there, and if there is, would check where it goes, and if there is no wire, then how do i lay a new one?

And yes many thanks to Rich /ubbthreads/images/graemlins/worthy.gif
 
Last edited:

Specter

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Apr 20, 2008
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367
Location
Karachi, Pakistan
If, i could get a wiring diagram, just for the dash wiring including the connections of the small fuse box by the pedals, my work would become a lot lot easier, because then i would be able to identify and correct any sort of tampering done in the ignition switch wiring. /ubbthreads/images/graemlins/dunno.gif
 

toybreaker

iconoclast
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Swapped cars are a special case. /ubbthreads/images/graemlins/rofl.gif

There's no way to match it to a diagram, because there is no diagram for that particular combination.

In fact, if the engineers knew what we were doing to their pride and joy, they'd probably commmit hari-kari right then and there. /ubbthreads/images/graemlins/tongue.gif

That said, we can still do a very clean job of it, with a little planning.

At the minimum, you need to supply a clean battery voltage to the mpi relay.

This means an 10awg, (or mayhap an 8awg, if you feed the fuel pump too,) run from the battery over to the relay area of life.

It will need to be fused very near the battery.

One easy way to do it is to use the factory fuse block at the battery terminal.

If you have a vacant location just add another fuse, bolt it down in the holder, run your wire into the car, and you're good to go.

You can also just run a suitable inline fuse, just try and get as close to the battery as you can.

The size ( awg "gauge" ) will vary depending on how far the wire run is, and the current it's expected to carry for the entirity of it's service life. Sizing the wiring correctly at the start ensures a long service life. /ubbthreads/images/graemlins/smile.gif

The connections you will need to make on this wire are pretty straightforward.

One leg will need to feed the mpi relay at terminal 4.

One leg will need to feed the ecu at terminal 6o.

This will take some of the load off the key, and go a long way towards solving your voltage sag problem. /ubbthreads/images/graemlins/smile.gif



Another approach is to add a simple single relay system, in parrallel with the original set-up.

It could be set-up to run half of the stuff the mpi is now running, and/or some of the hotel load stuff that is now being fed by the ignition switch.

(The hotel load is everything the car has to have in order to run. Ecu, fuel pump, ignition coils, and the like.)




Another choice is to wire up your own relay panel.

Many times, when I do a swap, I'll just make one of these up.

You can place a pair of relays on the board, fuse their circuits, and it'll actually simplify things in the long run.

Splitting the load between two relays will roughly double the life of the components.

It will also help ensure that all the circuits see optimal voltage, with plenty of current to keep things operating up to their original potential.

Many of the issues people have with swaps is in the wiring.

Random misfires, cars that won't hold a tune, coils failing, fuel pumps burning up, and random esoterica shitting the bed at inoprotune times is enough to kill the fun of any project. /ubbthreads/images/graemlins/frown.gif

(not to mention wear down some shoe leather... /ubbthreads/images/graemlins/rofl.gif )

Bodged wiring is a player in most of those failures.

It's fully preventable, and in fact, it's much easier to do a nice job of it before the magic smoke has left the harness. ( it's devilishly hard to put the smoke back in /ubbthreads/images/graemlins/wink.gif )

At any rate, your wish is my command.

If you would like, I can build up a simple little rig that will do the job, and ship it out to you.

Between Rich's excellent diagrams, Chris's experiences and any help Telecaster can give us, we should be able to do a clean install that will live a long and trouble free service life.
 

Specter

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367
Location
Karachi, Pakistan
Wow thanks for being so much supportive. This really feels great. I hardly find anyone in my friends who supports my "galant" because its a "galant". Even the mechanics and electricians here try to run away from these cars, do not know why, these cars are not that hard to work on. But this makes me feel very good, and considering you guys are " THE GUYS " in the vr4 business, coupled with one of the most supportive forums around these days, i do not think i can get any better source of knowledge and advice.

Yes Sir we will start with the battery connection to Pin 62 of ecu and terminal 4 of the mpi relay. For the fuse, i would like to use the stock mpi fuse location in the under hood fuse box, mine should be spared with no wires connected because my car was not an efi car before the engine swap, so lets see what i find in there. And I THINK i have some empty spaces for an after market relay which i could use for the reasons you stated. If i could pull this off, it would be pretty much a stock setup.

I'll get some 10awg wire, a 20a big mpi fuse, an after market relay too, and will report here back.

Oh and i just legged the Pin 6 of power transistor with Pin 3 of the ignition coil, and had that wire coming through the firewall under the dash and has to be connected to Pin 7 of relay. I also connected Pin 7 of the relay to the ignition wire i had coming under the dash. So i just need to connect these two wires i mentioned and one circuit of ours would be complete.

Engine bay pic of coil and transistor connection, tapped them up after taking the pic.
img.php
 

Specter

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Location
Karachi, Pakistan
By the way, what length of wire would i be needing, from the battery, till the ecu, just a rough estimate in "foot/feet" My ecu is at the left hand side, you must have noticed, the car a RHD.
 

Specter

Well-known member
Joined
Apr 20, 2008
Messages
367
Location
Karachi, Pakistan
By the way, i had this relay lying since a lot of years with me, do not know why it was taken out, what was it for, and whether it works or not.


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Part No : MB302373
On top of it, its written 12.8v 85c/m
Any thoughts on it?
 

Specter

Well-known member
Joined
Apr 20, 2008
Messages
367
Location
Karachi, Pakistan
It is almost done, i am getting good 12v current to all the related ecu pins, good ground at pin 38 and good 12v current at the mpi relay pins too. I got a relay and an inline fuse similar to the one you posted in pics toy breaker. I was cranking the car to start and it would not start. I check the current at spark plug wire and there was none. It could be two things. I have connected the black/white thick wire to the coil pack and added an ignition wire to it. The diagrams show it to be connected with pin 62 of ecu and pin 7 of relay, i do not think it would make a difference but i will try. If this does not working out then my transistor is dead. The car was giving current trouble when we started this little project, maybe the transistor was dieing back then. I will first try a new transistor i have lying around, if that does not work then do the connections as per diagram, if you have any idea what might be wrong then pls do mention.
 
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