CA18ET S12 won't start (flooded)

[tamiya]

Hi,
I fitted a nistune type 1 board on my nissan s12 ECU (33F01). It worked nicely with stock injectors. (All the engine is stock)
After upgrading stock injectors (270cc) to 600cc ones, I can't start engine anymore. Spark plugs keep getting carbon fouled.
In this post I will briefly tell what I understood during the multiples readings of various Nistune provided documentations.

When flag "start sw" is active, "fuel map" is not used
It is the "Crank enrich" that is used with "temp enrich".
"Crank enrich" is a list of injection duration in ms for a given temperature. The colder it is, the longer the injection duration.
"temp enrich" is a factor applied to crank enrich value, according to coolant temperature

Once engine started, we stop cranking, "start sw" flag is going off and ECU is now reading the standard fuel map.

Here is the procedure I follow.
- opening Nistune, selecting S12 vehicle and opening main ECU file related to my engine.
- connecting consult with F4 after turning ignition on
- resizing injectors with dedicated feature from 270cc to 600. Resulting K const is 104. I left "adjust cranking tables" ticked so that engine can avoid flooding during cranking. The computed value seems OK in cranking table as it is 55% lower than what it was originally.
- i modified injector latency as it seems to be a common rule that the larger an injector, bigger latency is invoked. It was 550us stock, I entered 850us.
- I reduced "Min Load (TP)" values by 55% as my injectors are larger.
- synchronizing all this with ECU and it won't start. I get a few "fires" starting but not enough to keep it running and it stalls immediatly. Plugs are not wet but carbon fouled..
All my ignition circuit is almost new and ran 1000kms nicely. Timing is spot on.
Honestly I don't know where I am supposed to look at now... My wideband sensor is telling me that it's lean while I crank but as plugs gets fouled, I dont trust it :/
Temperature sensors are reading correct and plausible values.

If anyone have an idea, I will be glad to try it !
Thanks

[Matt]

I started from factory 30F00 and came up with K=82 constant (since injectors are about 1.2x stock ones)

Try this lower number. I'm not sure how you got K=104

[tamiya]

Hi Matt,
I'll give it a try thanks.
This difference might be caused by the fact that my ECU is a 33F01 and I am using a 33F01 main image instead of the 33F00 that you used for your screenshot ?
Did not knew that such a small change in K constant could cause a non-starting engine condition

EDIT : I compared 33F00 and 33F01 roms and I can see pretty large differences between both of them. K const is a bit smaller on the 33F00 one, this might explain why you find such a difference between my value and yours. Also, 33F00 is for a car with 02 sensor and a catalyst but my 33F01 did not come with a 02 sensor neither a catalyst.

[tamiya]

Still not starting
It catched pretty quickly but stalls immediately.
Please find attached the .bin

[tamiya]

A little video to show what's happening.
Brand new plugs gapped to 0.8mm.
Timing is still spot on.

https://youtu.be/wBHLK7PCFu8
Injectors are these ones https://www.ebay.fr/itm/153814226101?mk ... nl%3Dmkcid

[Matt]

I'm wondering about that 30F00 ROM file! I don't think that is factory. I think it has been tuned (changed)

So we will stick with the 30F01 file then. Normally they should be very similar to each other (just a revision change)

I'd try giving it more fuel in the crank enrich table

Once you get it to 'kick' try reducing K if you think it is flooding. Were the injectors flow tested?

[tamiya]

Thanks a lot for your answer.
I will try this in the morning (as it is 3:42am here, I think my neighbors won't appreciate my tuning experiences )
The only thing that did not get tested in my setup are those injectors. As they were brand new, I trusted them blindly.. and a problem is that my OEM injectors died in the removal process so I can't fit them anymore to give it a try.
I will keep you posted.
Again, a huge thanks for your help.
Have a nice day!

[tamiya]

So it starts with some brake cleaner.
Injectors really seems to be guilty...
However, they "tick" when using a stethoscope.

I unmounted Injectors and they aren't clogged. Spray pattern is decent and a very similar between all fours.
Unfortunately no one wants to flow test them as they are some hose barb injectors and they do not have the required material to test them.

However, they require a lot more current to open them than OEM injectors.
A few months ago, I had a similar test with OEM injectors and a single AA 1.5v battery was sufficient to open all 4 injectors wired in parallel.
This time it was impossible. Current draw was too important so I had to use a 4V high amp power supply to open them.
They all got 2.6ohm impedance.
I am suspecting the wiring or ECU now... or maybe a few of them was "stuck" as they are brand new and my 4V power supply unlocked them ?

[tamiya]

EDIT : merged this post with previous one.

[Matt]

Ticking just means that the solenoid is opening the pin. So all four are spraying with your testing which is good.

The idea of lowering K constant is to reduce injection time for the larger injector, based on actual size vs previous size

It is a bit of a concern that more current is required for these

The fact that the car starts from initial crank means that it is either running from previous fuel in there (or some of the current fuel during initial crank). To test that, pull the fuel pump and crank until it doesn't crank further. Then set K constant to 0 (no injection almost) and then it will just run from crank enrich and it should just cough and stop (but not flood)

After that set K to say 50 (half of the current value) and see if that gets it going

[tamiya]

Ticking just means that the solenoid is opening the pin. So all four are spraying with your testing which is good.

The idea of lowering K constant is to reduce injection time for the larger injector, based on actual size vs previous size

It is a bit of a concern that more current is required for these

The fact that the car starts from initial crank means that it is either running from previous fuel in there (or some of the current fuel during initial crank). To test that, pull the fuel pump and crank until it doesn't crank further. Then set K constant to 0 (no injection almost) and then it will just run from crank enrich and it should just cough and stop (but not flood)

After that set K to say 50 (half of the current value) and see if that gets it going

Thanks for replying.
Should I set min to load to 0 ?
At the moment I do not have successfully started the engine.
I am getting an oscilloscope by Friday so I should be able to watch injector pulsations. I am receiving a set of OEM injectors tomorrow also.

[tamiya]

So it started with some brand new OEM injectors.
I tried everything with the "600cc" from PEC and it ain't started.
I might give the "DSM 450cc" a try as they seem pretty common in S12 CA18ET tuning community... Or I will switch to a new fuel rail with standard injectors.
Thanks for everything Matt.

[Matt]

We would not set min load to 0 since that may result in MAF undershoot and low TP values which will cause stall conditions

Good that its going with the OEM injectors, if 450CC is common (GTR ones are 444CC but need dropping resistors) then that should work