TBI to Z31 MPFI swap

[Tungsten]

ok good luck with the wiring for that one

[Kingman]

ok good luck with the wiring for that one

 

 

What are you talking about? I have the ENTIRE Z31 wiring harness. The only thing I'll want to do after making the truck run and drive, regarding the MAF, is to shorten the length of the wires going to it. Easily done with a solder gun, shrink tube, and vinyl glue. Pretty common sense to me...

[Kingman]

I've gotten a lot of the wiring sorted out and I FINALLY located a firm TBI Pathfinder wiring diagram. Sorted out the fuel pump and ignition system, which is pretty much all that needs to be carried over. I won't have an interlock switch anymore, as the ECU is for an automatic. So hopefully no idiot friends decide to go turn-key and smack something. I'll have to be sure to warn them DO NOT TURN THE KEY OVER OR YOU WILL DIE!

 

Also got some of the intake tubing figured out, went to Home Depot and bought a bunch of 3" ABS plastic tubing in black, so that should solve that. I'm going to use the Z31 air box since it's outlet is designed to run a 3" system and doesn't have the MAF sensor and @!*% stuck to it like the MPFI Pathfinders do. I'll need to figure out a square to round adapter since the inlet on the air box is square, the factory intake spot is round on the Pathfinder.

 

 

Outlet on the air box.

 

Inlet.

 

Rough guesstimate of the air intake.

[MY1PATH]

for some reason I think the clutch safety swich is part of the ingniton systems and not part of the ECU systems...

But If you've already looked into that and found I'm wrong then nevermind...

[Kingman]

for some reason I think the clutch safety swich is part of the ingniton systems and not part of the ECU systems...

But If you've already looked into that and found I'm wrong then nevermind...

 

There's a pin, in a plug that goes to the ECU that is for the clutch neutral switch, M/T only. It is pin 10 in the diagram I posted on the last page. That pin is empty since this ECU is from an automatic.

Edited September 16, 2010 by Kingman

[Kingman]

Have I mentioned that I hate wiring yet?

 

Got some things sorted out with a TBI wiring diagram, finally!

 

Fuel pump: Pin 108 (white/red)

Load signal: Pin 22 (gray)

ECU power source: Pins 27, 35 (green and green)

Ignition signal wires - Resistor: Pin 3, Transistor: Pin 5, Transistor: Pin 14 (white, gray or white, white or blue/white)

Neutral switch: Pin 10 (doesn't say)

Ignition switch: Pin 9 (black/yellow)

Main relay: Pin 6 (blue/red)

 

So I've got a few wires that go to the same thing that are the same color. Great! Now to figure out exactly which ones I connect where so I don't mis-match something and start a smoke show.

 

The tachometer is ran off the ignition resistor wire, in case anyone was wondering.

[frecklecolouredbrain]

Kinda funny thing. I was reading this yesterday and thinking you've got some work cut out for you on the wiring match-up. checked in today and as soon as I saw that you'd figured it all out, I remembered that I have ALL the info you needed written on a printed out z31 wiring diagram from when I was thinking of swapping out fuel systems and going turbo.

[ZombeeXXX]

finally found it.

 

 

You don't have to use the old style z31 ecu. Those of us with 84-86's look for 87 and up ecu's as an upgrade.

 

Here

Is the different ecu's we have to choose from and the important differences.

 

What's important is that an 88-89 NA z31 uses a high impedence injector driver and maintain teh zirconium sensor. I dk what the wd21 o2 sensor is stock but the 88-89 T z31 uses the titania. Of course you'd have to get it programmed to NA maps.

 

It's kinda up to what o2 you decided to run i must've missed that.

 

 

That old of Z won't have clutch interlock. The clutch switch is for cruise. All the more reason to keep idiots out from behind your wheel.

 

 

Plz ditch the crappy z31 airbox in exchange for any decent cone that will fit your piping once you get it laid out.

 

The PROM chip on 88-89 NA and turbo ECU’s can be swapped. That is, if you want an 88-89 ECU and would like to use a Zirconium type oxygen sensor you can put the turbo PROM in the NA ECU. This should save a lot of time in swapping out the sensor bung, sensor, and re-wiring. Hence, the desirable unit for 84-85T cars would be an 88-89NA ECU, and the desirable unit for 86-89T cars would be the 88-89T ECU.

 

The Turbo ECU has a daughter-board for the detonation sensor, Non-turbo’s do not. (Note: the TP/RPM feedback region for the detonation sensor is very small, it is not even used under boost or at any time above 3000RPM.)

 

The Turbo and Non-turbo cars do not use the same type of idle control. The wiring in the engine harness is also different for these controls. Not really an issue: I, and many others have perfectly running cars with all idle control devices removed.

 

84-85 ECU’s (all) have been reported to have a small lean surge problem during the first 30 seconds or so of engine warm up. This is most likely an issue with the cold-start enrichment and can be remedied by switching from CHTS to FTS signal during startup.

Edited September 18, 2010 by ZombeeXXX

[Kingman]

I've got a free set up, I'm not changing any computers or injectors any time soon and I'm aware of the different Titania and Zirconium O2 sensors. I also won't ditch the air box for an open cone filter, I do wheel this truck and here there is a lot of mud and rain in Washington. I actually just got back from a late night wheeling trip where the mud holes we had to go through on the trail were almost over the hood. Actually one was. I was riding in my buddy's 4Runner, he put an open cone on a few days ago and already found out why it's a bad idea. Sucked some water into the engine and packed the filter with mud. Sealed box is a much better option for any rig going off road.

 

I believe the Pathfinders use the Titania sensor, since it's 17MM and the '84 Zs use the Zirconium which is 22MM. I was on the site linked in the last post for the sensors and computers a few days ago, and have been studying up on everything since I got this Pathfinder and had originally intended on doing the swap. I just never looked through the wiring until not too long ago.

 

Later on, when I feel like gaining more performance I'll run the newer computers with larger high impedance injectors, with a gutted plenum, 200SXSE 60MM throttle body, Walbro fuel pump, and whatever else. Once Mister510 gets his turbo situation handled and reliable, I'll take notes on his work and start on my own.

 

Tomorrow I'll be cutting the hole out of the firewall and start to yank/splice the wiring harnesses together with the needed wires.

[Kingman]

Kinda funny thing. I was reading this yesterday and thinking you've got some work cut out for you on the wiring match-up. checked in today and as soon as I saw that you'd figured it all out, I remembered that I have ALL the info you needed written on a printed out z31 wiring diagram from when I was thinking of swapping out fuel systems and going turbo.

 

Yeah, it's a pretty good amount of work... Hopefully it will be worth it.

[Kingman]

So now I know which wires I need to change over, but I have two wiring diagrams telling me slightly different things pertaining to the coil set up. I also soldered and wrapped a lot of wiring that got messed up from the start, which had to do with mice eating some away and the guy I got the motor from who's friend I guess started yanking on everything and broke quite a few things that I've finally replaced. I hate non-lead solder, it fcsking sucks!

 

 

[frecklecolouredbrain]

looking at them they are the same. all the wires match up to the right pins and components. I just looks like the 2 manual arranged things differently. If the first one is from Mitchell's go with that one. My mitchell's diagram (1989) was spot on to the pont where almost all the nca(no coloour assigned) were all the same colour.

[Kingman]

Yeah I'm sticking with the more complete one. I started yanking the harness and labeling stuff, the few hours I spent already made me grumpy.

 

Would you mind sending me the info you have, so I can compare it? And I did some more extensive tracing and found that the Crank Angle Position Sensor is responsible for powering the ECU, pin 6 that goes to the ECU main relay is only to actuate it. Weird!!!

[frecklecolouredbrain]

lemme know what you need

[Kingman]

Well I'll be damned, it fits! I can tell there will be an issue with torque twist on the motor, so I may have to massage upwards a little bit to allow for that. Other than that it fits fine... That went a little easier than I had expected.

 

[beavis0076]

wow... this is awesome! a definite *high five* to you.

maybe when your done, you can come fix my fiat! hahahahahaha

[Kingman]

I've already got 4 bikes to strip down and sell the parts, another Pathfinder to put a *built* engine and transmission in to, an Alpha Romeo Spyder to put back together with a rear transaxle, a '67 Impala to continue restoring, an '89 Bronco II that needs a new motor and some work, a Tahoe that needs new head gaskets, an '89 300ZX that needs a timing belt, water pump, cam seals, and a transmission cooler, and whatever else that might come along.

[Tungsten]

Well I'll be damned, it fits! I can tell there will be an issue with torque twist on the motor, so I may have to massage upwards a little bit to allow for that. Other than that it fits fine... That went a little easier than I had expected.

 

 

So is that like turning your firewall off?

[Kingman]

Um, yeah haha pretty much. I can't say it enough, I'm so not looking forward to the wiring!

[MY1PATH]

your interior gonna be loud

[Kingman]

Maybe, I have a ton if insulation to pack in there. I may stick a bunch of the tarmat material I used for the rest of the sound deadening in the truck behind there as well.

[Kingman]

Now I've got to trace the firewall lines on a cardboard replica so I can make a box out of sheet metal that will conform to the firewall. I may need to figure something out for another throttle cable, I have the factory one routed behind the intake and over the top to the throttle body. It's kinda long and close to the firewall so I might cut it down a little.

 

[JamesRich]

I've already got 4 bikes to strip down and sell the parts, another Pathfinder to put a *built* engine and transmission in to, an Alpha Romeo Spyder to put back together with a rear transaxle, a '67 Impala to continue restoring, an '89 Bronco II that needs a new motor and some work, a Tahoe that needs new head gaskets, an '89 300ZX that needs a timing belt, water pump, cam seals, and a transmission cooler, and whatever else that might come along.

 

And I thought I had a lot of @!*% to do!

I commend you on your vision, you have more nuts than me! When I would have seen how far the intake needed to go back I would have just tossed it in the shed with the other junk I collected. Good luck on the rest of the project. After that the wiring will be easy.

James

[Kingman]

Thanks a lot man!

 

My mom wanders out to the garage every once in a while and stands there scratching her head. Most of my buddies that come over do that too. Not bad for an 18 year old kid I guess. I make a lot of my money by being the "mechanic" for other people's sheit. I enjoy it, most of the time...

[Kingman]

I changed my mind. Looking through more and more wiring, the wiring harnesses are damn near identical. I'll keep the TBI wiring harness and splice in only the wires that I need for the MPFI, mainly fuel injectors. I'll run those along the factory harness and change pins at the computer harness as needed. Much cleaner and surprisingly simpler. That way I don't have to swap coil wiring and all that BS.