Startup issue, Will not start without starting fluid.

[racinjitter]

Hi,

I recently installed nistune into an 88 Z31 n/a manual transmission ECU and I am running DSM 450cc injectors with 6.8ohm resistors. The issue I am having is that, the engine will not start with out starting fluid. Once it is started it runs until I shut it off. I tried a different .bin file that is know to work with another z31 with the same injectors. Same result.

I do not have anything on the intake manifold, all of the controls (IACV, EGR, FICD etc) are welded shut.

Is there a function that looks for those missing signals that is not allowing me to start the car normally?

Any help is appreciated.

[Bernardd]

Hi,

I recently installed nistune into an 88 Z31 n/a manual transmission ECU and I am running DSM 450cc injectors with 6.8ohm resistors. The issue I am having is that, the engine will not start with out starting fluid. Once it is started it runs until I shut it off. I tried a different .bin file that is know to work with another z31 with the same injectors. Same result.

I do not have anything on the intake manifold, all of the controls (IACV, EGR, FICD etc) are welded shut.

Is there a function that looks for those missing signals that is not allowing me to start the car normally?

Any help is appreciated.

I ran my L engine with that ecu with those same controls removed. It sounds like your startup tables are fubared. How does it run after started?

[racinjitter]

Well with the MAf not in the loop for the air intake, it runs pretty good up to 2k rpm. But it still has a few misses and hiccups.

[kenbam]

Just a thought, i have an rb20 with GTR injectors, also with resisters and find that if my battery is not completly charged, car will not fire. I put it down to cranking voltage being to low for injectors because of resisters. Cranks over fine abd fast enough but wont fire. Throw it on charger for 5 mins and it fires right up.

Going to get around to wiring up a resister bypass with a momentary switch just to get around the resisters during cranking

[racinjitter]

I was thinking of that, and I had the battery charger on the battery the whole time. I watched the ecu reported voltages and while not cranking I can vary the voltage from 12 vdc - 16.5 vdc. While cranking the ecu was reporting between 8.5 vdc - 11.6 vdc.

I also varied the base fuel pressure from 15psi to 60 psi. When I first tried to start the engine, I had the base fuel pressure at 30 psi.

During the first crank I was watching the data and the tps was reporting, and varying. But now, the tps is not showing any voltage. So I ordered a new tps sensor and I will be cutting the pig tail off of one of the spare engine harness that I have sitting around.

Would a TPS cause this issue?

[Matt]

TPS is only a switch on the Z31, and being a switch it should not report voltage on the screen so as long as you see the 'TPS idle' light when you have your foot off the accelerator pedal and it disappears when you press it down a little then it should be working fine

If not then might be a starting issue for your vehicle

What is the factory injector resistance for 1988 Z31 injectors. My R31 uses 4 ohm but thats equivalent of 1986 Z31 ECU

Whats the impedance of the DSM injectors? Add that resistance + 6.5 ohm and should match what the original 1988 Z31 injector is

If the resistance is now too large then it will be longer to open / close and may cause issues when at certain voltage levels (ie cranking). I'm not sure what my voltage is when cranking but 8 volts is getting pretty low since normal running minimum is 10 volts

[racinjitter]

Right the TPS on the Z31 manual transmission is actually a throttle switch that only tells the ecu that the throttle plate is now at idle. I didn't know that until I talked to Jason84NA2T.

I got the car running and it starts just fine now. I changed injector wiring harness back to "sequential or pre-campaign" rather than batch. I also mount the ecu, does the ECU ground through the case? Just wondering.

I can't recall the OE injector resistance off of the top of my head, but Enjoyrth (Rick) used the same injectors and resistors.

[Matt]

I keep hearing about the Nissan 'injector campaign' that was to do with lower impedance injectors and adding resistors into the wiring loom right?

The ECU case is just provides shielding against noise which will reduce when mounted against the chasis. Your USB cable shielding goes via a capacitor to the ECU casing to insulate the USB signal from noise (which causes disconnects if the noise is bad)

[racinjitter]

I keep hearing about the Nissan 'injector campaign' that was to do with lower impedance injectors and adding resistors into the wiring loom right?

You are correct Sir! When you have an 88-89 z31 and you want to run low impedance fuel injectors you must change your fuel injector harness back to original before the campaign was completed. Otherwise you will have this same issue that I did.

I completely forgot about the injector harness modifications and simply wired the resistors inline.

[Geoffy101]

from what i understand of the campaign wiring, is as follows;

prior to the change each injector is run seperately from the ECU.

The campaign wiring does not add resistors or remove resistors, it simply wires injectors 1,3,5 together and 2,4,6 together and runs them i believe from the injector drivers of 3 and 4.

This means that 1,5,2,6 injector drivers are sitting there disconnected, and that the engine is essentially running in batch mode all day long. Using the high impedance injectors there is no problem as they are in paralell and each recieve enough drive.

The problem arises when you put low impedance injectors and resistors in and you now have 6 loads in series parrallel and you get barely any voltage to the injectors.

Someone please correct me if i am wrong, but thats the way i understand it.

[vagabond]

I'm having the same problems Jitter did, but I had already rewired my Injector harness to pre campaign and added the resistors for the DSM injectors. Injectors were resized.


When the MAF is unplugged and battery has good charge the car will idle up to 2000 rpm. When I Plug the MAF in it will not idle.

This MAF, and CAS worked perfect before the conversion, so I am not certain that was the issue. Good power transitor, new CHTS harness and previously working CHTS.

The car is an 87 na, Turbo conversion and I am using an 88 NA ECU.

Would the differences in 88-89 ecu make a difference in the MAF's operation?

[Matt]

should make none in theory unless the ECU was modded for Z32

what voltage are you reading inside Nistune at idle and when you try and accelerate?

[vagabond]

I just got it to idle today, and I did not have a PC hooked up. I'll try again tomorrow with PC.

Back ground info:

New Battery (Trunk mounted)
4ga Ground wires
450cc DSM injectors with associated harness mods
ADJ. FPR @ 37-40 PSI
Stock Fuel Pump
Z31 MAF
Good Spark and fuel (cleaned plugs again today)
88 NA Nistune ECU.

[vagabond]

Didn't get it to start as of posting. Without cranking voltage is at 12.2V. Battery voltage dips between 9-8 volts when cranking. Would the Resistors, combined with the battery trunk relocation and this voltage prevent start up?

I'll need to leave it on the charger for a bit before I try again.

Also, I switched from the Stanza TB and TPS to a Stanza TB and Z31 TPS.

[bachig24u]

9 volts might just start a Carburetted engine if you are lucky.
Prolonged cranking will most likely cause electrical issues, low fuel pressure and a host of sensor faults.

If you battery can't hold over 11.0 volts for 10 seconds that it takes to fire up I doubt it's up to the task.

without any idle control system you need to either drill a hole of about 1/8 inch (start a fraction smaller if its a 4 cyl) in throttle plate or just find a way to screw the throttle plate open a few mm's.