DIY 94-97 to 98-99 Patch Harness Parts

[Jesters Deadd]

I'm only familiar with gen1 and gen2 but I'm pretty sure only gen1's have knock sensors. All other models don't.

This is wrong! All DOHC 3000gts have knock sensors.

[Jesters Deadd]

I have the harnesses for 1g, hybrid, and 2g available through morgon's motorsports (xwire), all come with a reflash plug and the 1g comes with an obdII port.

You can source all of the parts and DIY - but if you look at the prices of the hard parts and factor in S&H of the hard parts, then factor in your time, your loss of hair, etc, etc, your not saving your self any money and you are def costing yourself TIME. Now I have been fabbing these up for some time now. I make 10 to 20 at a time. I have had to teach my poor gf how to solder and junk because it is just such a PITA.

So, for the unconvinced:

Lets look JUST at the 99 ecu plugs:
28 Pin Plug 1 @ $2.50 ea add 17.00% for average S&H from DigiKey $2.93
28 Pin Plug Pin Retainer 1 @ $0.75 ea add 17.00% for average S&H from DigiKey $0.88
30 Pin Plug 1 @ $5.16 ea add 17.00% for average S&H from DigiKey $6.04
30 Pin Plug Pin Retainer 1 @ $0.75 ea add 17.00% for average S&H from DigiKey $0.88
35 Pin Plug 1 @ $2.73 ea add 17.00% for average S&H from DigiKey $3.19
35 Pin Plug Pin Retainer 1 @ $1.18 ea add 17.00% for average S&H from DigiKey $1.38
Sig (Small) Pin 75 @ $0.38 ea add 17.00% for average S&H from DigiKey $33.35
Pwr (Large) Pin 18 @ $1.04 ea add 17.00% for average S&H from DigiKey $21.90

TOTAL $70.55 - Thats just for the 99 ECU side
Figure about $10 to $13 bucks for the 1G or 2G ecu connector.
Oh - and if you have a 1G, you need an OBDII Port. And dont forget the mitsu reflash plug.

So figure at LEAST $100 in parts. No Wait, add solder, heatshrink, and wire. You shouldn't just slap any old wire into those 99 ecu connectors. The pin crimp specification is 1.4mm wide on the signal pin. Soooo if you crimp 1.7mm wide because you are not using ultra thin wall (TXL) wire, you will have to work real real hard in stuffing all those pins in the connector. But I suppose if you want what they pass of as primary wire at your local auto parts store, then by all means have at it.

Now you got your conversion table - what pin goes to what pin. Don't make a mistake or you might be buying a new ecu. You get everything fabbed up and how much time did you spend? I bet at least an hour or two. Do you figure your lost time with your family and friends is only worth $2.50 hr? Any way you slice it, it is so much nicer to just order the part, slap it in, and walk away . . . that being said . . .

Von can yell at me later - I have the 1G / hybrid / 2G connectors available through Morgan's Motorsports (xwire). Everything is built with extra thin wall TXL cross-linked polyethylene wire rated at 60v and between -59°F to 275°F. Resistant to moisture, grease, oil, gasoline, and most solvents. It meets or exceeds SAE J1128. Check with xwire for pricing.

Or you can go to your local junkyard and most 98-2004 mitsubishi ECUs will have the three plugs and wires for a 99 VR4 ECU. I even checked out the four plug diamante and montero ECUs and the three needed pigtails can be cut from the wire harness of the car. I just cut them when I grabbed the ECUs I was testing. The forth plug even had a bunch of extra pins for the three plugs you would use.

TOTAL $ depends on the yard(I got the ECU and plugs for $24)- Thats just for the 99 ECU side
Figure about $10 to $13 bucks for the 1G or 2G ecu connector.
Oh - and if you have a 1G, you need an OBDII Port. And dont forget the mitsu reflash plug. (cut that from your donor car too free with the ECU I bought)

So figure at LEAST $37 in parts. No Wait, add solder and heatshrink... but I got an ECU too.
Now I did have to go to a junk yard, not the nicest place. And the wire diagrams aren't easy to figure out if you don't have both manuals.

Just letting people know there are options, plus maybe you can source some used plugs a little cheaper.

[Greg E]

Or you can go to your local junkyard and most 98-2004 mitsubishi ECUs will have the three plugs and wires for a 99 VR4 ECU. I even checked out the four plug diamante and montero ECUs and the three needed pigtails can be cut from the wire harness of the car. I just cut them when I grabbed the ECUs I was testing. The forth plug even had a bunch of extra pins for the three plugs you would use.

TOTAL $ depends on the yard(I got the ECU and plugs for $24)- Thats just for the 99 ECU side
Figure about $10 to $13 bucks for the 1G or 2G ecu connector.
Oh - and if you have a 1G, you need an OBDII Port. And dont forget the mitsu reflash plug. (cut that from your donor car too free with the ECU I bought)

So figure at LEAST $37 in parts. No Wait, add solder and heatshrink... but I got an ECU too.
Now I did have to go to a junk yard, not the nicest place. And the wire diagrams aren't easy to figure out if you don't have both manuals.

Just letting people know there are options, plus maybe you can source some used plugs a little cheaper.

Gate found a legit 96 Stealth spoiler for something stupid cheap like $12 from a junk yard... You can get lucky!

There's always ways to cut corners but to be fair, it's not like Brett's harnesses are a ripoff either. It's not like he's gouging us for huge profits. They're quality, convenient and take away a huge headache. If it's worth it to you, then jump on it. If not, then don't. No biggie.

[99 vr4]

Most junk yards around here won't let you in to cut the connectors off of the wiring harness. There are a couple of pick and pulls . . . but they usually don't have anything worth going after . . .

[Jesters Deadd]

Gate found a legit 96 Stealth spoiler for something stupid cheap like $12 from a junk yard... You can get lucky!

There's always ways to cut corners but to be fair, it's not like Brett's harnesses are a ripoff either. It's not like he's gouging us for huge profits. They're quality, convenient and take away a huge headache. If it's worth it to you, then jump on it. If not, then don't. No biggie.

I completely agree... except for the cut corners comment. Oem connectors and wiring is quality stuff.

[Greg E]

I completely agree... except for the cut corners comment. Oem connectors and wiring is quality stuff.

My apologies. I didn't mean to imply cutting corners in quality, I'm talking about saving yourself $$ by making one yourself.

[Drummer]

Gate found a legit 96 Stealth spoiler for something stupid cheap like $12 from a junk yard... You can get lucky!

There's always ways to cut corners but to be fair, it's not like Brett's harnesses are a ripoff either. It's not like he's gouging us for huge profits. They're quality, convenient and take away a huge headache. If it's worth it to you, then jump on it. If not, then don't. No biggie.

At $250, the work involved in making the harness correctly is fair. If you have the money and not the time/patience/skill, its worth it. It is entirely possible to make your own, given you have all 3 of the previous things.

[99 vr4]

I just thought I would share this with you all . . .

There are several issues with regards to using a SL ECU:

Namely there are no provisisons for the boost gauge, the fuel pressure selonoid, the fuel pump relay (low speed), and the wastegate selonoid. Additionally the knock sensor circuit is designed differently.

What does this mean? No Boost Gauge. No fuel pressure control via ECU. The VR4 has a two stage fuel pressure system. Besides having the fuel pump on low, the fuel pressure selonoid bleeds air from the fuel pressure regulator on the rail keeping idle pressure low. Fuel pump locked on HI all the time. And finally no stock wastegate control.

And don't forget the knock sensor circuit is significantly different between turbo and non-turbo models. Basically, you will get phantom knock when there is none, and will not read knock when there is knock. This is not a 100% all the time issue, but it is significant enough that I would not take the chance.

You will have to have an aftermarket boost gauge, aftermarket fuel pressure regualtor, fuel pump locked on hi, and an aftermarket boost controller.

And of course the spun bearings that come from the ECU not seeing knock when there is knock and reduced performance from the ECU pulling time when it sees phantom knock.

There are even more issues with the base distributor model. And even more issues if you have a non 3000GT ecu. Trust me, I know. I have reverse engineered most of the critical circuits to include knock sensor, IGN Transistor feedback, fuel pump and pressure, and O2 sensors.

[Jesters Deadd]

What!??? A bad idea? really? Having an inexpensive completely tuneable ECU that is nearly plug and play with an adaptor harness is a bad idea?
I have tested it on my car and IT WORKS GREAT!

1. No stock boost gauge... the stock boost gauge doesn't even measure boost, you should have a real boost guage anyway!

2. No stock two speed fuel pump control... hotwired fuel pump. This is like stage one upgrade stuff.

3. No stock fuel pressure solenoid control...Install an aftermarket fuel pressure regulator and hook up the vacuum from the intake. The fuel pressure solenoid only cuts vacuum to the fuel pressure regulator during hot starts. Most people have already disconnected this with no noticable affect.

4. No wastegate control... install a manual boost controller or a better one truboost etc.. Again this is stage one upgrade stuff.

5. Knock Sensor!... I tested this on my VR4 and got the same amount of knock on the same program as my 99VR4 ecu at the same locations... it wasn't 100% scientific but it was very repeatable...

Basically have a boost gauge, hotwired fuel pump with an adjustable fuel pressure regulator and a boost controller and you are set with an 98/99 SL ECU. This is all stuff you will need for stage one upgrades. You will have all the tuning ability of the 98/99VR4 for much cheaper than a 99VR4 ECU. Just ask questions and know what you are doing before you do it.

[99 vr4]

jester . . . for an experienced tuner such as your self . . . the lack of a completely functional knock sensor is apparently a non issue. But for the normal DIY, this should be an area of concern. Big concern.

I am not saying that having a completely tunable ECU is a bad idea. Having a completely tunable ECU in which you THINK the knock sensor is working 100% is a bad idea. Would you remove your knock sensor completely and keep driving your car? I don't think so. If you knew your knock sensor was bad would you throw caution to the wind and say forget about it? Maybe you would. But you shouldn't.

I will try to shed some light on this in non-technical terms. The knock sensor is a piezo element which generates an electrical signal in response vibrations very much like a microphone generates electircal signals in response to sound waves. Think of the knock sensor circuit like an amplifier, audio filter, and signal processor. The filters and amplifers are hardware based while the signal processor is software based. If your filters and amplifers are not tuned the sound you get will be junk. You can't fix it the signal processor. Lets say your have a new audio amp for your car. It can pump 300 watts from 20 to 20K. But your speakers are rated from 70 to 15K. So you throw in a filter but miscalculate and your filter passes 50 to 5K. So now you have no high end (sounds like shit) and your driving too much bass to your speakers. Does it work? Yes. Does it work well? No. Will your speakers last? Time will tell. Probably if you don't drop any deep bass at high power.

I know you would never really mismatch your shit like that, but you are if you use an unmodified ECU. If you say its a non issue - then I wouldnt let you near my car if you paid me. I know your a smart man. I know your an experienced tuner. I also know that no one else has reported this problem. But you have heard of the Diamante and Montero "wierd" knock issue. Well guess what? Its the same circuit as what is in the SL ECU. Its only a matter of time. Sorry to bust your bubble. - Brett