Rb25det neo tuning and injector size

[skyboy318]

Ok I have a rb25det neo like in the description, iv found that the base map runs pig rich. Now I run a z32 maf stock injectors. My question is iv always been told neos have 320 cc injectors but when I hit factory size on the injector size option it says 380 cc. That could be the answer of why I'm running rich.

[Matt]

NEO engines have 380CC injectors (normal RB25DET have 370CC)

The factory button just pulls the injector size out of a list of injectors for each vehicle. The injector size is not kept in the ECU

Whenever a resize is performed it will adjust the K constant (or Total injection multiplier in FP ECUs).

Hold the car at cruising speed and adjust K/TIM until AFRs are around 14.7:1 and near zero trims (STFT/LTFT gauges). Then check AFRs over the rest of the map

If you have changed to the Z32 MAF then you need to rescale the load TP scales, or if you have FP ECU then adjust K constant until the vehicle operates within the current TP scales (and offset fueling required by adjusting TIM parameter)

[skyboy318]

where do i find the stft/ltft gauges to see if they are zero. also how will i know or figure out how to rescale the load tables. sorry im new to this and want to learn.

[Matt]

Please read the 'Nistune software users manual' for details on the gauges (FTS/FTL are the proper names) and Nistune tuning guides about scaling is covered in detail (Nistune.com > General Documentation)

[skyboy318]

ok i am at a loss. im trying to get my car running right but unless im at stock psi its like im hitting a brick wall like MAF cut but that would be impossible im running z32 maf and wanting to run 12 psi. everything is stock but around 3500 rpm it cuts in and out in and out if i run more than factory wastegate. please help idk if its a tuning issue or what. i need to add i have the map/boost solenoid turned off in nistune but still plugged in. could that be the issue.

[Matt]

Okay you should probably start again. What is your ECU part number showing in Nistune?

If AA50F for example then load
ER34_RB25DET_AA50F_MT_FP_maps.bin (Feature pack)

If AA500 for example then load
ER34_RB25DET_AA500_MT.bin (non Feautre Pack)

Then do Operations > Resize MAF (Z32)

At this point you will need to either
1. Feature Pack: Reduce K constant until load cursor just touches last column of fuel map (increase TIM)
2. Non Feature Pack: Reduce increase TP load scale points until load cursor just touches last column of fuel map

If neither works then find where you got the MAF from. Many fakes which floating around that just dont work

[skyboy318]

Ok downloaded base tune from rom pack, did the maf change to z32. Car runs sluggish as all get out. Could this be a k constant issue? Under load it's running 10.0 AFR. It feels almost like the timing is retarded or something.

[Torque]

Does the car run fine with the OEM MAF?

If 'yes' chances are that your Z32 is either damaged or a fake.

Take a log of he MAF / timing values were the car starts to run 'funny'

[Matt]

After doing the Z32 MAF resize, the scales of the ECU will be set to suit the maximum HP of the Z32 MAF (around 550hp) but if your car is not 550hp (well it wont be with those injectors) then it time to rescale the TP load scales for fuel and timing

However if you have feature pack, instead reduce K constant (and increase TIM accordingly)

Currently I suspect you may only be accessing half of the scaling within fuel and timing maps

[skyboy318]

Ok after further study load scaling is off. My map trail is going past the 160 which is what the fuel load table is set. When I check how far the load goes it's max at like 196-200. Another thing I found weird is my ign timing load scale is set 208. Shouldn't the fuel map and ign timing load scale be equal? Also I was scaling up k constant when now I know I should scale it back. Could that explain why under boost it goes pig rich at the sign of boost? I was going to ask about throttle enrichment but if it's a k and Tim issue that will be easier to fix.

[Matt]

Some ECUs have different scales for fuel and timing. Fuel scales do not go as far, so the ECU uses the fuel values in the last column from 160 .. 208 and upwards.

Normally we make the timing and fuel scales same range (upto 208) to make tuning easier

So you have feature pack (with TIM parameter?). Changing from RB25DET to Z32 MAF will increase K significantly. Yes you will need to pull it to a lower value so you are reaching below 208 (and increase TIM to get fueling back on track)

[skyboy318]

That makes alot more sense now thanks for the help and patience.

[skyboy318]

Ok so my k constant is set at 540 and Tim is set at 522 it's running alot better still rich but haven't messed with fuel map yet runs stronger than ever at 13.5 psi. So does those settings sound correct? Also I have 1000 cc injectors waiting to be put in once I get my bigger turbo so for future reference once I put those on k needs to be made higher like on what the original setting of 600 and what not ?

[skyboy318]

Matt do you know how much psi of boost is safe with factory injectors? I have a rb25 turbo with steel components instead of the ceramic ones?

[Matt]

Should not be running rich, but 14.7:1 on cruise will get you in the right range. I cannot tell you if the settings are correct, you need to watch your gauges and those will tell you. Or take a log doing gradual pull (if safe to do so) and also cruise and post here

With the 1000CC injectors you will have a lot flatter fuel map once those are in

K should not need adjustment with injectors, only the TIM parameter. Injectors do not affect load referencing in the maps

Factory ceramic turbo about 12psi. We saw no gain pushing it to 14psi on my R34 NEO. With RB25 turbo I dont think you will max the factory injectors, but will probably detonate firstly