TBI to Z31 MPFI swap

[Kingman]

Have I mentioned I hate wiring lately?

 

Ditched the charcoal canister and mounted the coil where that was, plenty of room for the intake and what not. I spent about an hour with a bunch of degreaser and rags cleaning the engine bay. Now it's all shiny blue and easier to work with, instead of being covered in oil, dirt, and metal shavings.

[Kingman]

The two little red dots below the washer tank is where the coil will be.

 

Shiny!!!

 

A big bundle of wiring...that's only sorting out the MAF sensor wiring from the Z31 harness.

 

MAF wiring singled out.

 

I'm a little confused about why Nissan connected the MAF sensor and CAPS together. Not quite sure what I'm going to do about that one yet... And the fuel injector wiring is going to piss. me. off. I'm fairly sure there's 1 power wire to all 6 injectors, which is red, and the rest of the green wires to each injector are the grounds through the computer, which signals those for the firing sequence. At least that's how it seems on paper. I was getting delirious going through wiring so I think I'm done for the night...or morning.

Edited September 27, 2010 by Kingman

[MY1PATH]

Ditched the charcoal canister and mounted the coil where that was,

 

AH HA! your not coppying me.

 

as far as the injectors, some engines had no-sequecial fire which means they all go at the same time. If this is the caes The ony reason to have them pinned numerically correct is so you get the right failure code for the right injector and don't have to test each one...

[BoneZ]

 

the fuel injector wiring is going to piss. me. off. I'm fairly sure there's 1 power wire to all 6 injectors, which is red, and the rest of the green wires to each injector are the grounds through the computer, which signals those for the firing sequence. At least that's how it seems on paper.

 

It is very common to have a common power for the injectors and have the ECM control the ground to complete the circute. This is done because it causes less strain on the ECM.

[Kingman]

AH HA! your not coppying me.

 

as far as the injectors, some engines had no-sequecial fire which means they all go at the same time. If this is the caes The ony reason to have them pinned numerically correct is so you get the right failure code for the right injector and don't have to test each one...

 

I wish it was the case, but they are all sequential fire until the computer goes in to safe mode and then a pre-set map runs everything open loop and the injectors in batch fire. But each ground is a different color so it's just plug and play to pins 101-106.

[Kingman]

Coil.

[Kingman]

Getting closer, Mister510 kindly sent me some injector parts I had lost along the way so I was finally able to fit the injector rail on. I'm greatly annoyed by the fact that the fuel lines for the stock TBI would fit perfectly on the feed and return lines on the Z31 system, if they weren't backwards. so the feed line would fit perfectly on the return line, and visa versa. So I'll need to make a pit stop at a junk yard soon.

[ennacac]

WOW, what a project, I guess this gives me a second thought about the Xterra VG33E V-6 swap I was thinking of doing in my 89 Pathfinder.

 

Tom

[MY1PATH]

WOW, what a project, I guess this gives me a second thought about the Xterra VG33E V-6 swap I was thinking of doing in my 89 Pathfinder.

 

Tom

 

 

keep in mind the 3.3 and all asociated equipement was modeled after fitting a similar size shape engine bay so you will have easier time than kingman here with his 300zx designed intake, and such... You can also run a 3.3 off your tbi if you wish...

[Kingman]

Yes, that. A Pathfinder motor and intake is designed for, well, a Pathfinder so it will fit fine. My Z31 intake is longer in the back, because the engine bay in the 300ZX is quite a bit longer and the motor sits further forward in the engine bay, allowing room for the back of the intake and exhaust cross over pipe with room to spare. Am I crazy for doing this? Most certainly...

[Kingman]

Just an update. Nismopu came down from Woodland to check on my progress, we got the MAF sensor wiring figured out which has been hanging me up for a little while. Turns out I can use the TBI wiring for the Z31 sensor, only difference is the Z31 has a heater element that the Pathfinder doesn't. Makes things easier. Injectors are also easy, pins 101 and 106 at the computer to run all 6 injectors. Yeeeeeeee! It's getting closer, I'm shaving off some all of the emissions stuff and an accessory air regulator...thing (pointless), it makes wiring a lot easier since that thing runs wires through a few other sensors.

 

I also originally had the fuel lines backwards, I was tired... so the stock fuel lines fit perfectly on the new intake. I need to run the whopping THREE wires to the computer for the injectors and then that part will be done, then finally mount the upper plenum, extend the TPS wiring since the TBI wiring is the same but too short, figure out a hose for the upper plenum coolant hose, go get some flexi-tubing for the air intake, and find a way to mount the air box. That about covers it really, there's not much more work to do. Once it's running I'll take it in to an exhaust shop and have them weld in a new bung to mount the Z31 oxygen sensor. So I may be running a while without one, won't hurt anything just have a larger appetite.

Edited October 6, 2010 by Kingman

[Kingman]

Why does making a coolant hose that starts at 3/4" ID and opens up to 7/8" ID have to be so farking hard? Couple trips to NAPA to even find a hose that did that, a bunch of cut up metal tubing, and lots of guesswork... here's the disaster now known as my thermostat bypass hose for the heater core.

 

 

I also ran the fuel injector wiring to the ECU. Wasn't that productive of a day...

[MY1PATH]

you know you can stick those hoses in the oven at ~240+ degrees and force one end over a ~1/8 larger (1.5"+ hoses can even go ~1/4" larger) fitting and when it cools it will mold that way. so if you find one that makes all the bends you need open one end up a little.

Edited October 6, 2010 by MY1PATH

[Kingman]

Everything is on, I tried starting it and it was a no-go. Just straight cranking.

 

I'm glad it didn't start, I learned the ECUs don't take kindly to:

A) Me tapping the wrong wire for an injector, that on the TBI computer is a ground and on the Z31 computer is a 12V output. Thankfully I didn't fry the computer, that would really piss me off.

Batch-fire injectors being ran through only two switched circuits instead of 6 to carry the load. I thought I could cheat and run only 2 pins from the ECU to the injectors since mine was retrofitted at the dealer for a campaign they had. The newer computers run full sequential, the older ones were retrofitted to batch-fire since they were blowing computers left and right. So I have to run the 6 wires from the computer and splice them into the 2 feed lines for the injectors, not a big deal at all.

 

Fix that tomorrow and hopefully it'll run. I'm not too hopeful though...

 

[MY1PATH]

sequential fire is better anyway. You'll have more consistant AFR ratios and less rich spikes.

better power & better mpg

[Tungsten]

First of all, awesome work!

 

I'm anticipating a comparison of the pathy intake plenum to a 300zx intake plenum on a Z31 motor in a Pathfinder.

 

So did you move that MAF sensor closer yet or is that still holding? I missed the part that it was about 2.5 feet away on the stock Z31 application. In that case there should be a small difference moving it closer to the throttle body.

 

BTW, If the motor shakes, it won't ram the plenum into the firewall will it? That intake looks a little close in terms of clearance to me.

 

 

Here are some useful links to read (if you haven't done that already):

 

http://en.wikipedia.org/wiki/VG30E#VG30E

 

http://en.wikipedia.org/wiki/Nissan_300ZX#Z31

 

You can see what was done to the VG engine over time.

 

This new V6 (2960 cc) Single overhead cam engine was available as a naturally-aspirated VG30E or a turbocharged VG30ET producing 160 hp (119 kW) and 200 hp (150 kW) respectively. The engine was either a type A or type B sub-designation from 1984 to April 1987, while models from May 1987 to 1989 had a W sub-designation. The W-series engines featured redesigned water jackets for additional cooling, fully floating piston wrist pins, and more power—165 hp naturally-aspirated and 205 hp (153 kW) turbocharged.

 

Maybe the 5 extra hp came from the new injection method?

Edited October 7, 2010 by Tungsten

[Kingman]

sequential fire is better anyway. You'll have more consistant AFR ratios and less rich spikes.

better power & better mpg

 

It is. Eventually I will run a '87+ ECU where it will actually run full sequential and not burn up the load transistors.

[Kingman]

First of all, awesome work!

 

I'm anticipating a comparison of the pathy intake plenum to a 300zx intake plenum on a Z31 motor in a Pathfinder.

 

So did you move that MAF sensor closer yet or is that still holding? I missed the part that it was about 2.5 feet away on the stock Z31 application. In that case there should be a small difference moving it closer to the throttle body.

 

BTW, If the motor shakes, it won't ram the plenum into the firewall will it? That intake looks a little close in terms of clearance to me.

 

 

Here are some useful links to read (if you haven't done that already):

 

http://en.wikipedia....iki/VG30E#VG30E

 

http://en.wikipedia....issan_300ZX#Z31

 

You can see what was done to the VG engine over time.

 

 

 

Maybe the 5 extra hp came from the new injection method?

 

Thanks! A little bit of what I've done is sort of "for now" because I don't have a ton of money to buy all the parts I'd like to. It was painstaking taking the time to perfectly measure every wire feed, solder the connections, vinyl glue and shrink wrap them, then follow the wires with electrical tape and finally guttering. All of the wires I've ran are that way, at least I'll know there won't be any reliability issues with that part.

 

You are correct, the intake will hit the lip above the firewall. There's 1/4" of room above, under mild bumps and acceleration it shouldn't twist quite that bad but under full torque load or huge bumps it will, guaranteed. I need to rework it a little, but once the motor is running.

 

I haven't figured out the air intake routing. I'm going to just run some 3" flexible tubing straight off the throttle body, MAF next to that, and then bend it to where I want the air box mounted. The stock pieces I have simply won't allow for what I want. I have it set up now with no filter attached just for a test start and revving. To road test it I'll then need to run a secure intake.

The sequential fire VS batch-fire is a strange debate. Theoretically it should give better performance and economy, but it doesn't. Real world numbers have shown tons of times that the only net increase in economy and efficiency is at or a little bit above idle. Less atomization of fuel when sprayed into a closed valve. Above a low point, there's virtually no difference and at best 1MPG increase.

 

However to run a turbo... sequential fire is desirable...

 

I also didn't like how the fuel lines were unevenly spaced on their way up to the fuel rail, so I made some holder things with zip ties. Zip ties hold the world together!

Edited October 8, 2010 by Kingman

[Kingman]

I'm 99.999999999% positive I fried the Z computer. I rewired the injectors to match what the Z car ran, didn't help. Fuel pump quit coming on and priming like it should with the computer also, but when I plug the TBI computer in it primes like it should. The fuel system was working fine. There's also no more spark when cranking, only a spark when the ignition switch is turned to OFF.

[Kingman]

I do not understand. I put in a new computer, triple checked the wires and grounds, etc. #$!&er still just cranks. Something is not right and I can't figure it out! Now for some reason the fuel pump still won't come on, but comes on fine with the TBI computer.

 

Oh, then if put the positive lead from a Fluke meter to the 12V out for the injectors and ground the other lead, the fuel pump relay clicks and the pump comes on but never shuts off.

 

I'm so farking confused!

Edited October 11, 2010 by Kingman

[Kingman]

Okay, I'm totally lost. There's 12V going to the coil, fuel pump, CAPS, MAF, CHTS, relays, etc. The damn fuel pump still will not run and the coil will not spark. I've tried different coils and transistors too!

 

I can see the truck sitting in my garage for the next year...

[Kingman]

Hmmmm, figured out the fuel issue. It literally fell in to my hands! I was jumbling around with some wiring at the computer then CLICK hummmmmmmmmm CLICK. By accidentally jumping the safety and fuel pump relays, the fuel pump relay unstuck and powered the pump. I noticed it wouldn't always turn on so I put a new relay in and it primes every time I turn the key.

[Kingman]

AHHHHHHH!!!!!!!!!!!!!! IT RUNS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[JamesRich]

AHHHHHHH!!!!!!!!!!!!!! IT RUNS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Alright! Good persistence! Now say a little prayer of thanks. I think I would have set it on fire by now. So how does it run? You leavin rubber yet?

James

 

I just noticed the posting time, get some sleep man.

Edited October 12, 2010 by JamesRich

[MY1PATH]

Alright! Good persistence! Now say a little prayer of thanks. I think I would have set it on fire by now. So how does it run? You leavin rubber yet?

James

 

I just noticed the posting time, get some sleep man.

 

 

james doesn't sleep, I seen him txt me questions @ 3am when I'm working a 12hr night shift @ work lol.

 

Grats james, don't keep the neighbors up.

Edited October 12, 2010 by MY1PATH