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Fuel System Problems - Injectors Needing Too Much Adjustment

The Mafia

By The Mafia,
in Engines & Forced Induction

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The Mafia Grand Master

The Mafia

Posted
Posted

Hi Everyone

I've got a bit of an issue. I have to increase my injector correction too much in order to get my car to run properly. Here are the details:

Nismo 555cc injectors

Bosch 044 completely rewired to the battery

Fuel Rail Checked

PowerFC Settings:

stock 370cc / nismo 555cc = 0.666666667 x 100 = 66%

nismo 0.71ms - stock 0.52msec = 0.19msec

The correct settings are 66.6% and 0.19ms lag adjust

66% and 0.18ms Lag time adjust = Car won't start

66% and 0.18ms Lag time adjust AND massive injector increase in idle load cells = Car starts and runs, heaps lean everywhere else.

72% and 0.18 ms Lag time adjust = Car starts and runs, and map is consistantly good for fuel

66% and 0.45 ms lag time adjust = Car starts and runs, and map is consistantly good for fuel

Ok here are the catches.

1. Same problem with Nismo injectors, and Factory injectors. So its not the injectors.

2. Changed out the fuel pump twice. Same problem.

3. Changed the FPR, same problem.

4. FPR is getting good vacuum signal.

5. No Boost leaks.

6. Same problem on RB25DET stock, and RB25\30 with cams.

7. DaleFZ1 had the EXACT same setup (Injectors, Fuel pump, AFM, ECU, etc, and set to 66% and 0.18ms lag adjust and he had no problems.

Here are most likely the only things that could be wrong now:

1. Injector Voltage. Multimeter says they are 12.3 \ 12.4 volts

2. AFM?? Could this have an effect? And why?

3. Kink in the fuel line? I'm hesitant on this one because the problem can be replicated at idle. A Kink would only effect mid to high load? Plus, with the doctored injector settings, the car runs ok with plenty of fuel up top.

This is really a pain in the bum. Any input would be greatly appreciated.

jarrod83 Community Regular

jarrod83

Posted
Posted

This is not really a solution.. just a similar comparison.. when i had nismo 740ccs in my car.. even tho they were twice as big as standard.. 370/740 = 50%.. i had to set them to 55% to get my tune similar to the stock injectors and fine tuned it from there.. i never really got the idle perfect it would be rich oneday lean the next.. either a air leak or you may have to relearn the idle.. i was just too lazy.. it runned fine. ill check the injector times for you in an hour

Jarrod

kjb_r33 Experienced

kjb_r33

Posted
Posted (edited)

I think your doing it wrong, the calcs your doing are if your going backwards, to the 370's.

I think the lag time for the nismo 555's is around .7 to .8 of a sec.

*edit*.

Seems as if im way off base and your not after the actual lag/void time.

Too used to nistune

Edited by kjb_r33
The Mafia Grand Master

The Mafia

Posted
  • Author
Posted

thanks for the responses.

I've tried to idle learn a number of times, but it didn't make a difference, because just remember that the rest of the map is super lean on the "correct" settings.

jarrod83 Community Regular

jarrod83

Posted
Posted

Im a bit confused to your reference to the "correct settings", as i thought the % was just a trim to the overall base injector duty cycle.. whats wrong with increasing the %?.. when i was running 27psi i had to turn the % up a bit more than the 55%, i always thought that correction was just to get your tune in the ball park of your old injectors so it can be driven to a shop and tuned?? Im probably wrong tho :)

Jarrod

JonnoHR31 Grand Master

JonnoHR31

Posted
Posted

66.5% and .18 are the correct settings for nismo 555s

check fuel pressure. i know you changed the reg but i had the same problem, tried 3 different regs which worked fine before i put them in my car, later discovered they were all dead after seeing my car. cracked the shits and bought a tomei reg and it fixed everything

T04GTR Grand Master

T04GTR

Posted
Posted

tunes dont just fall away. either its a injector problem, or its a faulty ecu. (that is if it was fine and now it isnt..)

from the sounds of it you may need to do some swapsies with some friends who have the same afm...

The Mafia Grand Master

The Mafia

Posted
  • Author
Posted
66.5% and .18 are the correct settings for nismo 555s

check fuel pressure. i know you changed the reg but i had the same problem, tried 3 different regs which worked fine before i put them in my car, later discovered they were all dead after seeing my car. cracked the shits and bought a tomei reg and it fixed everything

I am looking into this too. I need to find myself a fuel pressure guage. It will be a quick one because as I said earlier, the problem is right on idle. And is always there.

tunes dont just fall away. either its a injector problem, or its a faulty ecu. (that is if it was fine and now it isnt..)

from the sounds of it you may need to do some swapsies with some friends who have the same afm...

Injectors are perfect. I've put factory ones in and they have the same behaviour.

Adriano Grand Master

Adriano

Posted
Posted

Are you trying to run your previous rb25 fuel map with the rb30 and just adgust the scaling? That should work if the afm is the same, however the rb30's do seem to need more fuel? Is o2 feedback off, maybe the initial start has killed the sensor? Definately get a fuel pressure gauge on it to be sure. At the end of the day if the car runs consistently well with the settings you have put in it i wouldnt be overly concerned. Do you have a wideband you can leave on it for monitoring?

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