Apexi SAFC - any views on this device? - GT-R Register - Official Nissan Skyline and GTR Owners Club forum

GTR-Zilla · 7th August 2005, 10:59 PM

for the time being im running a mines ecu.. i aint got a clue what cc inj its mapped for. i know roughly that you can do some clever things regards to fueling on the apexi super afc...

any one go any experience on this, or is using one in their GTR?

tweenierob · 8th August 2005, 08:05 AM

The only experience i have of one of these was on a GTIR, it didn't work too well on that... my wideband showed very minimal changes in fuelling.

You also have to consider that the way the SAFC works, it changes the MAF readings seen by the ecu which also means ignition changes IIRC.

Rob

Not to say it isn't any good on a skyline...

GTR-Zilla · 8th August 2005, 07:22 PM

hmmm il skip that idea then

TOP SECRET · 8th August 2005, 11:56 PM

Piggy Back controllers allow stock ECUs to do things that they normally can't do, like run larger injectors or deal with boost. Remember that piggyback controllers work by altering sensor signals before they get to the ECU.

Most of the time, the primary signal being messed with is the Map Sensor. This is critically important in a Speed Density car. The Map Sensor is used by the ECU to guess how much air is going into the car, and therefore how much fuel to supply in order to match airflow. When you "lean" out a car with an AFC, you are simply decreasing the Map Sensor signal - the ECU responds to the decrease in manifold pressure by supplying less fuel. When you "richen" a car with an AFC, you are simply increasing the Map Sensor signal - the ECU responds to the increase in manifold pressure by supplying less fuel.

The change in fueling happens for a reason: if you look at a fuel table, Map Sensor values correspond with columns. When you increase or decrease the signal from the Map Sensor, you are simply making the ECU use a different column than it originally would have used.

But wait, isn't the Map Sensor used for determining ignition requirements too? When you "lean" out a car with a Piggy Back, you also in all likelyhood advanced timing. When you "richen" a car with a Piggy Back, you also in all likelyhood retarded timing. Look at trends horizontally (as MAP changes) in an ignition table, and you will see why this happens. This helps explain why so many boosted cars running on the "AFC hack" have issues due to excessive ignition advance.

The bottom line: Piggy Back Controllers suck because you cannot independently adjust fuel and ignition. Any changes to fueling will produce a change in ignition too, and often this is undesirable.

Cheers,

Simon

Jakester · 9th August 2005, 11:54 AM

Are the HKS Fcon and Greddy EManage not Piggybacks?, do they both "suck"?

TOP SECRET · 9th August 2005, 05:40 PM

No, the GReddy E-manage is generally a piggy back as well as the AFC, but you can edit fuel and ignition seperately.
The F-Con V Pro is a complete Standalone Unit, not a piggy back.
The E-Manage is, my oppinion, the best piggy back on the market. The new Ultimate should be very good as well. If you wanna go with a piggy back, try the e-manage, not the apexi stuff.

GTR-Zilla · 9th August 2005, 07:43 PM

so the f con v pro is a totally stand alone unit? why do people refer it to a piggy back unit?

AlexJ · 9th August 2005, 07:54 PM

i dont think a safc is totally evil

probably less harmfull to run the ignition map a little wrong than it is to rn with the fueling as rich as the stock map will set it if you have a free flow exhaust

PS I'm sure topsecret knows the difference between a MAP sensor and an AFM and that he knows a std gtr uses 2 AFMs and not a MAP sensor

TOP SECRET · 10th August 2005, 01:45 AM

yep i know, that wasn't a text made for skyline's only, just a small "wiki" for piggy backs generally. I won't use ever an AFC hack in a skyline. That's like put an VW Engine in to a Porsche

Every flashed PROM is better than an AFC hack, trust me.
I don't know why people do this with the F Con. If it's just a piggy back, why the hell is it soo difficult to tune it ? No no, it's a complete standalone unit like the stuff from Motec (m48 i.e.) or the APEXi PFC - difference is just that you need a wiring harness, the PFC is a plug & play unit.

7th August 2005, 10:59 PM	#1 (permalink)
GTR-Zilla Banned Join Date: May 2005 Location: London Posts: 2,099	Apexi SAFC - any views on this device? for the time being im running a mines ecu.. i aint got a clue what cc inj its mapped for. i know roughly that you can do some clever things regards to fueling on the apexi super afc... any one go any experience on this, or is using one in their GTR?

8th August 2005, 08:05 AM	#2 (permalink)
tweenierob GTROC Member Join Date: Aug 2003 Location: herts Posts: 1,833	The only experience i have of one of these was on a GTIR, it didn't work too well on that... my wideband showed very minimal changes in fuelling. You also have to consider that the way the SAFC works, it changes the MAF readings seen by the ecu which also means ignition changes IIRC. Rob Not to say it isn't any good on a skyline... __________________ 599hp R35 Gtr www.trracing.co.uk T62 Going back on for track WTF!! :D Addicted to Snett!! Roll on the 24th of jan £99 rocks!

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8th August 2005, 07:22 PM	#3 (permalink)
GTR-Zilla Banned Join Date: May 2005 Location: London Posts: 2,099	hmmm il skip that idea then

8th August 2005, 11:56 PM	#4 (permalink)
TOP SECRET GTR Register Member Join Date: Apr 2005 Location: Frankfurt / Germany Posts: 45	Piggy Back controllers allow stock ECUs to do things that they normally can't do, like run larger injectors or deal with boost. Remember that piggyback controllers work by altering sensor signals before they get to the ECU. Most of the time, the primary signal being messed with is the Map Sensor. This is critically important in a Speed Density car. The Map Sensor is used by the ECU to guess how much air is going into the car, and therefore how much fuel to supply in order to match airflow. When you "lean" out a car with an AFC, you are simply decreasing the Map Sensor signal - the ECU responds to the decrease in manifold pressure by supplying less fuel. When you "richen" a car with an AFC, you are simply increasing the Map Sensor signal - the ECU responds to the increase in manifold pressure by supplying less fuel. The change in fueling happens for a reason: if you look at a fuel table, Map Sensor values correspond with columns. When you increase or decrease the signal from the Map Sensor, you are simply making the ECU use a different column than it originally would have used. But wait, isn't the Map Sensor used for determining ignition requirements too? When you "lean" out a car with a Piggy Back, you also in all likelyhood advanced timing. When you "richen" a car with a Piggy Back, you also in all likelyhood retarded timing. Look at trends horizontally (as MAP changes) in an ignition table, and you will see why this happens. This helps explain why so many boosted cars running on the "AFC hack" have issues due to excessive ignition advance. The bottom line: Piggy Back Controllers suck because you cannot independently adjust fuel and ignition. Any changes to fueling will produce a change in ignition too, and often this is undesirable. Cheers, Simon

9th August 2005, 11:54 AM	#5 (permalink)
Jakester GTR Register Member Join Date: Sep 2003 Posts: 347	Are the HKS Fcon and Greddy EManage not Piggybacks?, do they both "suck"?

9th August 2005, 05:40 PM	#6 (permalink)
TOP SECRET GTR Register Member Join Date: Apr 2005 Location: Frankfurt / Germany Posts: 45	No, the GReddy E-manage is generally a piggy back as well as the AFC, but you can edit fuel and ignition seperately. The F-Con V Pro is a complete Standalone Unit, not a piggy back. The E-Manage is, my oppinion, the best piggy back on the market. The new Ultimate should be very good as well. If you wanna go with a piggy back, try the e-manage, not the apexi stuff.

9th August 2005, 07:43 PM	#7 (permalink)
GTR-Zilla Banned Join Date: May 2005 Location: London Posts: 2,099	so the f con v pro is a totally stand alone unit? why do people refer it to a piggy back unit?

9th August 2005, 07:54 PM	#8 (permalink)
AlexJ GTR Register Member Join Date: Apr 2003 Location: TWsomething Posts: 293	i dont think a safc is totally evil probably less harmfull to run the ignition map a little wrong than it is to rn with the fueling as rich as the stock map will set it if you have a free flow exhaust PS I'm sure topsecret knows the difference between a MAP sensor and an AFM and that he knows a std gtr uses 2 AFMs and not a MAP sensor

10th August 2005, 01:45 AM	#9 (permalink)
TOP SECRET GTR Register Member Join Date: Apr 2005 Location: Frankfurt / Germany Posts: 45	yep i know, that wasn't a text made for skyline's only, just a small "wiki" for piggy backs generally. I won't use ever an AFC hack in a skyline. That's like put an VW Engine in to a Porsche Every flashed PROM is better than an AFC hack, trust me. I don't know why people do this with the F Con. If it's just a piggy back, why the hell is it soo difficult to tune it ? No no, it's a complete standalone unit like the stuff from Motec (m48 i.e.) or the APEXi PFC - difference is just that you need a wiring harness, the PFC is a plug & play unit.