injectors cutting out? neo ecu on LPG S1 C34 stagea

[Dan_J]

so s1 c34 nissan stagea non neo engine running r34 neo ecu with nistune, had to rewire injector loom for the different pinouts between r34 and s1 c34 ecu.
car is running( idling) on LPG vapour injection, was on a carby/venturi lpg setup before so upgraded to injection with the new injection components using the nistune to tune it.

problem i'm having is LPG injectors are cutting out while car is not in gear stationary( havent tried any driving yet) just reving out to 2-2.4k rpm, when the car is first started and quite cold i can rev the car out to redline, so it does happen after the car is warmed up or after the first warm up for the day +. to confirm the cut out i've seen on the nistune consult display that injector percent will drop while reving out and the AFR gauge will hit 22 although while just idling i've set AFR's to 11/1( too rich but doesnt change the end result when i have adjusted afr's back and forth) , also while reving out by the TH/B cable in the engine bay the pressure gauge on the lpg fuel rail will raise indicating that gas is not being injected so pressure build up happens.

i'm just trying to rule out that the problem is the nistune , although i have changed to two different sets of lpg injectors and two different LPG injection converters.

injectors are low impedance 3.0 oms etc so its not like i need a resistor pack and just to rev to redline while stationary the LPG components would flow for that purpose

have added the bin file of the tune below, although just note i've been playing with some setting to source this issue so of course the fuel map and settings in bin file doesn't look too proper

i would appreciate some ideas
thanks

[Matt]

problem i'm having is LPG injectors are cutting out while car is not in gear stationary( havent tried any driving yet) just reving out to 2-2.4k rpm

There is a normal fuel cut on decel (using the injection latency time during the cut) until it returns close to idle and then idle fueling resumes

when the car is first started and quite cold i can rev the car out to redline

Extra enrichment is added during cold starts which is adding more fuel keeping it going

so it does happen after the car is warmed up or after the first warm up for the day +. to confirm the cut out i've seen on the nistune consult display that injector percent will drop while reving out and the AFR gauge will hit 22 although while just idling i've set AFR's to 11/1( too rich but doesnt change the end result when i have adjusted afr's back and forth)

The fuel map doesn't look good but saw your notes at the end that it is for testing. You shouldn't be adding fuel like that to make the idle work. Check your MAF setup and look at the MAF voltage and TP on decel in 'stream mode' using the logger and AFR tracer
http://nistune.com/docs/Nistune%20MAF%2 ... 0Notes.pdf

Use the latency instead to increase fuel at idle and on decel where required but it seems at 1100uS you have it quite high already. Don't change the latency with voltage parameter as its not necessary.

injectors are low impedance 3.0 oms etc so its not like i need a resistor pack and just to rev to redline while stationary the LPG components would flow for that purpose

You should still use a resistor pack to avoid overloading the injector drivers in the ECU

[Dan_J]

thanks for the detailed response matt

There is a normal fuel cut on decel (using the injection latency time during the cut) until it returns close to idle and then idle fueling resumes

what i have meant to say is that when trying to reach 5-6k or redline rpm on low-mid throttle or at WOT, that the injectors will cut out on acceleration not decel, this happens at about 2-2.4k rpm much like limp mode

The fuel map doesn't look good but saw your notes at the end that it is for testing. You shouldn't be adding fuel like that to make the idle work. Check your MAF setup and look at the MAF voltage and TP on decel in 'stream mode' using the logger and AFR tracer
http://nistune.com/docs/Nistune%20MAF%2 ... 0Notes.pdf

i plan on ruling out the stock AFM that i'm running by swapping it out with another although i will do a log in stream mode and on accel

Use the latency instead to increase fuel at idle and on decel where required but it seems at 1100uS you have it quite high already. Don't change the latency with voltage parameter as its not necessary.

i've had a problem with the car leaning out and stalling when ever my twin thermo fans were en-gauged, although not much voltage drop at the battery was shown after a test with a multimeter, so adjusting the voltage parameter fixed this

injectors are low impedance 3.0 oms etc so its not like i need a resistor pack and just to rev to redline while stationary the LPG components would flow for that purpose

You should still use a resistor pack to avoid overloading the injector drivers in the ECU

correct, i must have gotten the differences mixed up, i will be wiring resistors into the injector loom to each injector. my electrical know how is average so would i need a 9-10 oms resistor on each injector?

would running low impedance injectors with no resistor cause this strange cut out by any chance?

[Matt]

what i have meant to say is that when trying to reach 5-6k or redline rpm on low-mid throttle or at WOT, that the injectors will cut out on acceleration not decel, this happens at about 2-2.4k rpm much like limp mode

One problem you are probably having is using an R34 NEO ECU in another vehicle without the traction control module fully functioning. Dare say you have error codes at the moment which will cause premature fuel cut

What I suggest is read the 'NEO tuning' document on our website and disable filter flags for Traction Control System (TCS) and boost sensor

Also set your boost sensor miminum voltage to 0 volts since I assume you do not have this connected. Increase your boost limit and TP max limit tables also

If that doesnt work I suggest changing your board to an 0V810 4WD stagea image which does not have ABS/TCS requirements which is what we do for any transplant

i've had a problem with the car leaning out and stalling when ever my twin thermo fans were en-gauged, although not much voltage drop at the battery was shown after a test with a multimeter, so adjusting the voltage parameter fixed this

You shouldn't be trying to adjust the tune around a electrical related problem. Although you measured the voltage at the battery you should be measure at the ECU or watching the battery in consult to see how far it drops. Check all grounding points since usually poor grounding results in strange voltage related issues if the battery is holding the power up otherwise

I'm not sure if using the low impedance injectors and overdriving them would directly cause the cut (I would like to think not) but cannot rule it out. About 8-10 ohms sounds about right if the NEO injectors are 14 ohms. I would need to measure some to check or you can look up online

[Dan_J]

so i've made some progress with different injectors however they are still low impedance at 3ohm or so. the problem i'm now having is when i do wire in 10w 10ohm resistors the injectors wont work at all so i wonder if the neo ecu is different and it needs 5w resistors or something more specific?

car will start and run with no resistors although after a few starts the injectors wont fire which i figure would be the injector drivers being over loaded. how do i check to see if the injector drivers are damaged and where on the ecu are they located?

thanks

[Matt]

One of the black chips on the R34 ECU is for the drivers. You need to trace the injector driver outputs via PCB tracks to the chip to locate exactly which one (I am not sure since its been a while since I fixed a NEO ECU)

10 ohm / 10W should work fine in theory, or just get some proper high impedance injectors to match the ECU