Supercharged/Turbocharged The increase in air/fuel pressure above atmospheric pressure in the intake system caused by the action of a supercharger or turbocharger attached to an engine.

Why am i adding so much fuel up top?

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Old Dec 11, 2010 | 06:18 PM
  #1  
MaximaSpd85's Avatar
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Why am i adding so much fuel up top?

setup:
dek, 5 speed
v2 w/ 2.87 pulley
440 injectors
z32 maf
walbro 255
AFPR, set @ 42ish psi with vacuum line off
EU

On the EU i tune by duration. From 3k to about 4900rpms the afrs are in the high 10s solid. My adjustments are at most +5m/s of fuel.

After that, the AFR rises slowly, and at around 5700 rpms it shoots up quickly over 12 so i back out. On my map i have adjustments of +12, +14, and +16m/s from 5k to redline. Adding more is working, although its not making a big enough difference anymore, but i mean dang, is that right? Do i just keep adding? Ive never run into such drastic adjustments, and im surely not maxing out anything (injectors, maf, etc) Whats the next step here? Keep adding? Raise pressure even more? or is there something i need to look into?
Old Dec 11, 2010 | 07:10 PM
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mastercater7's Avatar
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Have you tried adding fuel using duty cycle instead of duration?
Old Dec 11, 2010 | 08:54 PM
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put the vac line back on the fpr so it can adjust at a 1-1 rate with boost
Old Dec 11, 2010 | 10:15 PM
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MaximaSpd85's Avatar
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the vacuum line is on, i was just under the impression that your pressure read differently with line on vs off.

and na, i havent tried duty cycle instead of duration. u think thatll help?
Old Dec 12, 2010 | 11:04 AM
  #5  
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Originally Posted by MaximaSpd85
the vacuum line is on, i was just under the impression that your pressure read differently with line on vs off.

and na, i havent tried duty cycle instead of duration. u think thatll help?
It might since the EU can only add 20 ms of injector pulse IIRC. Since you have 440s the duty cycle will allow more volume of fuel. Also you can set up the auto-tune if you want, when you're using DC.
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