My VG30DETT swapped z31 cranks but won't start.

[ZettoSanIchi]

Is no one going to even mention the skateboard used as a hood prop rod??

Seriously, I would definately look at that fuel line, as stated the way its plumbed the filter is AFTER the injectors and everything.

What do you mean your ECU wasnt dead, you just had to turn the screw clockwise.... so it will go into diagnostic mode, but wont let the car start?

Yeah so apparently the fuel lines were swapped so I fixed that. And that's exactly what happens, it'll go into diagnostic mode and still won't start.

[NolimitZ32]

A few things:
1. Have you actually confirmed fuel, compression, leakdown, spark?
2. Have you checked that the injectors are opening (clicking) by removing and spinning the CPS?
3. Post up the entire ECU number not just the 22, I just want to check something, if you don't mind.

[ZettoSanIchi]

A few things:
1. Have you actually confirmed fuel, compression, leakdown, spark?
2. Have you checked that the injectors are opening (clicking) by removing and spinning the CPS?
3. Post up the entire ECU number not just the 22, I just want to check something, if you don't mind.

I have confirmed fuel, and no spark. I don't know what leakdown is. I haven't checked for compression.
I've also done a cas test and tested the harness.no clicks but harness is good.
The ECU numbers are as follows:
23710 41P01
A18-000 M63 7724

[NolimitZ32]

1. Leakdown: http://www.hotrod.com/articles/cylinder ... wn-tester/
2. Since there is no clicking (injectors opening) with the CPS cycling I would start by checking the output on the CPS itself, then if present by tracing the signal wires from the CPS back to the ECU to make sure that the wires aren't damaged. From there you can check to see if the ECU is outputting signal to the injectors. All in all your ECU may be fried and you need a new one (they're pretty cheap)
3. The ECU number is for an early production (07/89-08/89) JDM TT MT Z32 so the ECU matches the engine.
4. Sounds like the guy may have just told you a bunch of BS and in fact the swap you have is not nearly as convoluted as it first seemed. Check out my sig, follow the troubleshooting procedures in the FSM, if that doesn't get you anywhere we can discuss more options but at this point I believe that there is a straightforward solution to your problem.

[Zinprogress]

[Zinprogress]

As what nolimit said, next place to check is the cas input output. Getting codes was a good thing for sure and no, a knock sensor circuit will not cause a no start. If cas was giving an input output to the ecu then you would have injectors clicking. If you can get the injectors to click then you can move onto the ptu.

[ZettoSanIchi]

As what nolimit said, next place to check is the cas input output. Getting codes was a good thing for sure and no, a knock sensor circuit will not cause a no start. If cas was giving an input output to the ecu then you would have injectors clicking. If you can get the injectors to click then you can move onto the ptu.

I've already replaced the PTU and that didn't change the way the motor cranks and cranks and cranks. while working on my car a guy with a JDM FD RX7 told me the way it sounds when it cranks is indicative of a weak starter, or rather a weak ignition system(battery, cables, starter). He was having the same issue with his RX8 and replaced the starter and it fired right up. So I have a brand new starter in my room waiting for me to get back from out of country.

[Ace2cool]

Dude that ECU looks beat. There's corrosion all over it. You need to pop the case on that thing and see what level of corrosion is inside cause I'd be looking toward that direction.

[ZettoSanIchi]

So I went to Japan and sent my car to a specialty Z shop, Fairlady Motors. They said its the trash wiring job that's keeping my car from running. I'll update you guys when I get back and pick up my car. Thanks for all your help.

[ZettoSanIchi]

Hey guy. It's been a while but I took my car to a specialty Z shop here in Washington and they completely re did all the wiring and it actually starts! But... It won't stay on. It just cranks over, fires up runs for like 2 seconds and then dies. I checked the fuel pump and its working, I checked for fuel pressure and it's fine, plugs and coils are brand new. Right now the intercooler is disconnected and I chalked it up as "it won't run well without base boost and a MAF" so I just need to get the intercooler and MAF connected so it'll idle.. But I've seen the car run fine without any piping or the MAF connected. I'm really wanting to take this beauty to NissanFest on the 21st.

[Ace2cool]

If the MAF is plugged in it's metering zero air. Meaning it's compensating by running the injector at 0% duty cycle. Get everything hooked up and it will run I'd bet. Or if you're just trying to prove it can run without a MAF, unplug the MAF and it'll run on a closed loop feedback system, but quite poorly.

[ZettoSanIchi]

Ok. Thank you. I’ll get it all hooked up this weekend. I’m going to have to delete my headlight buckets to run the IC piping straight and without the crazy bends that the PO was trying to do. I’ll let you guys know.

[DCaff300ZX]

So I went to Japan and sent my car to a specialty Z shop, Fairlady Motors. They said its the trash wiring job that's keeping my car from running. I'll update you guys when I get back and pick up my car. Thanks for all your help.

Great choice with Fairlady Motors, Doug and Eric do great work. Saw your car there, VERY interesting. Doug should also have some helpful advise towards making it all work right.

[ZettoSanIchi]

Hey everyone I'm having a major problem with my twin turbo swap again, I'm having idle and bog down issues that seem to be dependent on the mass air flow sensor.

When the mass air flow sensor is unplugged the car will run under 3000 rpms and idle just fine, when it hits 3000 rpms the car cuts throttle and fuel, but i think that is just because the car is running in limp mode and limiting throttle cause it doesn't know how much air the engine is getting.

When the mass air sensor is plugged in the car struggles to idle with the brand new maf plugged in and to keep the car alive some feathering of the throttle is necessary to keep the engine alive and even above 3000 rpms it just seems like it wants to come back down and die.

The engine harness and mass air flow sensor are brand new, the wiring is custom from the guys at UP Garage/Fairlady Motors (read about them they do good stuff) and I bought an oem replacement from Enjuku Racing. I can't seem to figure it out.

[NolimitZ32]

Signs point to a big boost leak somewhere. Do a smoke test if you have the means. Or it could be that they used wire taps instead of soldering which ALWAYS causes issues.

[ZettoSanIchi]

Signs point to a big boost leak somewhere. Do a smoke test if you have the means. Or it could be that they used wire taps instead of soldering which ALWAYS causes issues.

Alright! I’ll check all of my piping when I get off work. For a while I was running dual intakes with the MAF on one side, and it worked fine with a Z31 maf. Should I switch it back? It seems like both of the new Z32 Mafs I bought don’t change anything. I’m going to take my car to Intec Racing in Kent and see what they say. After I try to figure it out of course

[NolimitZ32]

You can't just change/add/delete MAFs without tuning. If you're set up to run a divorced intake with a single MAF that means you're tuned to double the metered air for fuel calculations. If you were tuned for a Z31 MAF then your K-value will be way off for the Z32 MAF. If you've had no tuning and just started swapping MAFs you need to go back to what worked or get tuned for what you have/want.

[ZettoSanIchi]

You can't just change/add/delete MAFs without tuning. If you're set up to run a divorced intake with a single MAF that means you're tuned to double the metered air for fuel calculations. If you were tuned for a Z31 MAF then your K-value will be way off for the Z32 MAF. If you've had no tuning and just started swapping MAFs you need to go back to what worked or get tuned for what you have/want.

Good info. I’ll switch it to the original setup. I need to get it tuned real bad, even when it was working alright, it was running super rich. Do you know about EPROM tuning?

[NolimitZ32]

I do.