Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum - View Single Post - greddy E-manage ultimate/engine management systems????

Kingtal0n · 08-09-2012, 07:18 AM

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jk, dont search. ask here and people that are bored will be happy to explain (again) for the (improper integral) for x=1 to infinity times pie

Electronic "piggy back" devices, such as, SAFC, E-manage, F-ConV, EMS, etc...

ANYTHING that works with the OEM ecu to adjust fuel or spark...

Is a BAND-AID. It might get the job done, but it also might fall off and/or ooze blood everywhere.

dont ooze blood everywhere. Dont use a piggyback.

Ok, seriously, I get to troll you a little due to the nature of the question.
More info (less troll):

An E-manage or SAFC type of piggyback fuel adjuster modifies the input MAF or MAP voltage (which is generally 0-5v) to adjust the amount of fuel the ECU injects. This would work perfectly fine 100% of the time if IGNITION TIMING was not also affected, and if fuel MAPS were perfectly linear.

Fuel maps are not linear. Ignition timing is affected. A piggyback is a great thing for a MINOR adjustment in fuel, but not for actual TUNING. to properly tune an engine you will need full control over the ECU, such as with a Stand Alone computer (power FC).

Examples of when a AFC (air flow converter) is OK to use:
I have a 2.0L SR redtop engine with 370cc injectors and a T-25 turbo.
I upgrade the turbo to a T-28 and install slightly larger injectors (440CC).
It is OK to use a SAFC to compensate for these larger injectors in the mean time while I am waiting for my true stand alone to arrive. I also retard the timing at the CAS a few degrees in the mean time just in case.
Therefore, the AFC is a band-aid, while i wait for a real tuning solution to arrive.

Examples of when NOT to use a AFC:
I have a 2.0L SR redtop engine with 370cc injectors and a T-25 turbo.
I upgrade the turbo to a GT2871r and intend to produce 400RWHP.
The injectors are now 740CC. IT IS NOT OK to use a AFC to adjust the OEM ecu to work with these new large injectors!
I can dial them in to the point that the engine might run and drive around.... but if I produce any boost pressure, there is an enormous risk of blowing the engine due to too much timing and/or lean spots that are undetectable due to the MAF's non-linear voltage.

MORE info:
A maf sensor uses a PARABOLIC voltage curve, that is, A trinomial such as ax^2+bx+c is used to determine the airflow vs voltage output.
therefore, for EXAMPLE, If we shift the voltage from 5V to 4.5V, we might tell the ECU to inject 4% less fuel.
But if we shift the voltage from 5V to 4V, we tell the ECU to inject 11% less fuel.
and we shift the voltage from 5V to 3.5V, we tell the ECU to inject 23% less fuel.

Do you see how the voltage is NON linear as expressed with FUEL? A small voltage increase from 3V to 3.5V can be a very large increase in the amount of air the engine is moving, but a shift from 1.5V to 2.0V could be a very small increase in airflow. It is primarily for this reason that AFC do not offer true tuning solutions, are are merely bandaids.

08-09-2012, 07:18 AM	#2
Kingtal0n Post Whore! Join Date: Jul 2005 Location: South Florida Age: 42 Posts: 4,829 Trader Rating: (17)	SEARCH! jk, dont search. ask here and people that are bored will be happy to explain (again) for the (improper integral) for x=1 to infinity times pie Electronic "piggy back" devices, such as, SAFC, E-manage, F-ConV, EMS, etc... ANYTHING that works with the OEM ecu to adjust fuel or spark... Is a BAND-AID. It might get the job done, but it also might fall off and/or ooze blood everywhere. dont ooze blood everywhere. Dont use a piggyback. Ok, seriously, I get to troll you a little due to the nature of the question. More info (less troll): An E-manage or SAFC type of piggyback fuel adjuster modifies the input MAF or MAP voltage (which is generally 0-5v) to adjust the amount of fuel the ECU injects. This would work perfectly fine 100% of the time if IGNITION TIMING was not also affected, and if fuel MAPS were perfectly linear. Fuel maps are not linear. Ignition timing is affected. A piggyback is a great thing for a MINOR adjustment in fuel, but not for actual TUNING. to properly tune an engine you will need full control over the ECU, such as with a Stand Alone computer (power FC). Examples of when a AFC (air flow converter) is OK to use: I have a 2.0L SR redtop engine with 370cc injectors and a T-25 turbo. I upgrade the turbo to a T-28 and install slightly larger injectors (440CC). It is OK to use a SAFC to compensate for these larger injectors in the mean time while I am waiting for my true stand alone to arrive. I also retard the timing at the CAS a few degrees in the mean time just in case. Therefore, the AFC is a band-aid, while i wait for a real tuning solution to arrive. Examples of when NOT to use a AFC: I have a 2.0L SR redtop engine with 370cc injectors and a T-25 turbo. I upgrade the turbo to a GT2871r and intend to produce 400RWHP. The injectors are now 740CC. IT IS NOT OK to use a AFC to adjust the OEM ecu to work with these new large injectors! I can dial them in to the point that the engine might run and drive around.... but if I produce any boost pressure, there is an enormous risk of blowing the engine due to too much timing and/or lean spots that are undetectable due to the MAF's non-linear voltage. MORE info: A maf sensor uses a PARABOLIC voltage curve, that is, A trinomial such as ax^2+bx+c is used to determine the airflow vs voltage output. therefore, for EXAMPLE, If we shift the voltage from 5V to 4.5V, we might tell the ECU to inject 4% less fuel. But if we shift the voltage from 5V to 4V, we tell the ECU to inject 11% less fuel. and we shift the voltage from 5V to 3.5V, we tell the ECU to inject 23% less fuel. Do you see how the voltage is NON linear as expressed with FUEL? A small voltage increase from 3V to 3.5V can be a very large increase in the amount of air the engine is moving, but a shift from 1.5V to 2.0V could be a very small increase in airflow. It is primarily for this reason that AFC do not offer true tuning solutions, are are merely bandaids.