APEXi S-AFC?
05-18-2002, 02:20 PM
#1
Rennlist Member
Thread Starter
Join Date: May 2001
Location: Crofton, MD
Posts: 1,363
Likes: 0
Received 0 Likes
on
0 Posts
APEXi S-AFC?
I am going to be dumping some money on mods soon, and was wondering if anybody ever got one of these things to work in a 951? They are very tweakable piggyback computers and would give me a lot of adjustibility to make my current software work with the mods I am going to get. You can do all kinds of cool stuff with them...change injector duty cycle, advance/retard timing, mess with the AFM/MAF signal, display gauge readouts, etc. They are supposed to be universal and work with most any fuel injected car...I have never heard of anybody using one with a 951. Does anybody know why it wouldn't work?
05-18-2002, 04:04 PM
#2
It is being targeted at the Japanese build cars, it is a Japanese company. It looks like it might work, for the price it might be worth a try.
Here is a link.
<a href="http://www.apexi-usa.com/electronics.asp" target="_blank">Apexi web site</a>
Here is a link.
<a href="http://www.apexi-usa.com/electronics.asp" target="_blank">Apexi web site</a>
05-18-2002, 07:01 PM
#3
Advanced
Join Date: May 2001
Location: seattle, wa
Posts: 72
Likes: 0
Received 0 Likes
on
0 Posts
I've been curious about this for the longest time. It seems like a much more sophisticated alternative to the ARC.
I called Huntley Racing. They told me they have used them in the past and they didn't work well. Something to do with the S-AFC being digital and the adjustments being jerky. Not sure I understood their explaination, but he assured me that the ARC that Huntley sells is a much better fuel controller for the 951 (I also asked if changing to the MAF would make a difference and the guy said that it didn't make a difference; the S-AFC didn't work well with the "barn-door" or the MAF.)
Everything I've read about the S-AFC sounds like it should work just fine. The guy at Huntley never really gave me a good reason why it wouldn't.
I'd love it if someone would tell me why these things don't work on our cars.
I called Huntley Racing. They told me they have used them in the past and they didn't work well. Something to do with the S-AFC being digital and the adjustments being jerky. Not sure I understood their explaination, but he assured me that the ARC that Huntley sells is a much better fuel controller for the 951 (I also asked if changing to the MAF would make a difference and the guy said that it didn't make a difference; the S-AFC didn't work well with the "barn-door" or the MAF.)
Everything I've read about the S-AFC sounds like it should work just fine. The guy at Huntley never really gave me a good reason why it wouldn't.
I'd love it if someone would tell me why these things don't work on our cars.
05-18-2002, 11:28 PM
#4
Race Director
Personally, if I had to do it over again, I would never have gone with the MAF route knowing what I know now. Fiddling with the ARC2 is definitely not a precision procedure as anyone who've tried will tell you. On one of my buddy's turbo 240SX, we swapped the engine over a weekend, and dyno-tuned it perfectly on Monday in less than one hour with the Apexi S-AFC. With only three dyno runs we got 325rwhp @ 15psi from 2.0ltr.
If I was to start upgrading my car from scratch again, I'd skip MAF upgrades altogether and go straight to an aftermarket EFI system as the FIRST upgrade. This will allow you to tune your car optimally for each and every upgrade after that, including 3.3l twin-turbo engine swaps later.
Or an intermediate step would be to bypass MAF and go straight to MAP using the AFM-link product from these folks:
<a href="http://www.brdevelopments.com/link.html" target="_blank">http://www.brdevelopments.com/link.html</a>
If I was to start upgrading my car from scratch again, I'd skip MAF upgrades altogether and go straight to an aftermarket EFI system as the FIRST upgrade. This will allow you to tune your car optimally for each and every upgrade after that, including 3.3l twin-turbo engine swaps later.
Or an intermediate step would be to bypass MAF and go straight to MAP using the AFM-link product from these folks:
<a href="http://www.brdevelopments.com/link.html" target="_blank">http://www.brdevelopments.com/link.html</a>
05-19-2002, 12:55 AM
#5
bypass MAF and go straight to MAP using the AFM-link product from these folks
OK, looks good but were do you get the Manifold Air Pressure (MAP) signal from? Do you still need the MAF to make this work?
OK, looks good but were do you get the Manifold Air Pressure (MAP) signal from? Do you still need the MAF to make this work?
05-19-2002, 03:11 AM
#6
Three Wheelin'
<a href="http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic&f=11&t=000150" target="_blank">motronic tuning</a>
heres more to confuse you, look for the link to the motronic hacking.
But they are talking hotwire, is this the same thing we know as the MAF?
heres more to confuse you, look for the link to the motronic hacking.
But they are talking hotwire, is this the same thing we know as the MAF?
05-19-2002, 05:03 AM
#7
Race Director
"OK, looks good but were do you get the Manifold Air Pressure (MAP) signal from?"
From installing a MAP sensor like this:
Available from numerous sources for $60-75 retail.
"Do you still need the MAF to make this work?"
"But they are talking hotwire, is this the same thing we know as the MAF? "
The stock computer uses an air-flow and air-temp signal to figure out an injector duty-cycle to meter fuel. It can get these signals using the stock AFM and air-temp sensor with the drawback being the restrictive barn-door flow-sensor.
One step up would be a MAF (mass-air-flow) sensor which uses a hot-wire probe stretched across the air-flow. This sensor combines both the air-flow signal and air-temp data into a single air-mass signal (air-temp is usually clamped at a fixed value).
The next step up is the MAP (manifold-absolute-pressure) sensor which places nothing in the intake-stream for the least amount of restriction. This type of sensor measures the absolute-pressure in the intake-manifold and also has the advantage of never being maxed-out like AFM and MAF sensors can with too much flow. A separate computer is needed to combine the MAP signal with RPM data to arrive at an air-flow signal that is fed to the stock DME computer. The MAP also allows your compressor-bypass-valve (CBV) to operate as a BOV and vent air to the atmosphere for that rice sound (causing stumbling and possibly dying idle).
From installing a MAP sensor like this:
Available from numerous sources for $60-75 retail.
"Do you still need the MAF to make this work?"
"But they are talking hotwire, is this the same thing we know as the MAF? "
The stock computer uses an air-flow and air-temp signal to figure out an injector duty-cycle to meter fuel. It can get these signals using the stock AFM and air-temp sensor with the drawback being the restrictive barn-door flow-sensor.
One step up would be a MAF (mass-air-flow) sensor which uses a hot-wire probe stretched across the air-flow. This sensor combines both the air-flow signal and air-temp data into a single air-mass signal (air-temp is usually clamped at a fixed value).
The next step up is the MAP (manifold-absolute-pressure) sensor which places nothing in the intake-stream for the least amount of restriction. This type of sensor measures the absolute-pressure in the intake-manifold and also has the advantage of never being maxed-out like AFM and MAF sensors can with too much flow. A separate computer is needed to combine the MAP signal with RPM data to arrive at an air-flow signal that is fed to the stock DME computer. The MAP also allows your compressor-bypass-valve (CBV) to operate as a BOV and vent air to the atmosphere for that rice sound (causing stumbling and possibly dying idle).
Trending Topics
05-19-2002, 06:24 AM
#8
Racer
Join Date: Dec 2001
Location: Portland, OR
Posts: 388
Likes: 0
Received 0 Likes
on
0 Posts
[quote] The MAP also allows your compressor-bypass-valve (CBV) to operate as a BOV and vent air to the atmosphere for that rice sound (causing stumbling and possibly dying idle). <hr></blockquote>
Is it possible to put a stronger spring in an aftermarket BOV to keep it closed while idleing? Would this cure the stumbling and possibly dying idle?
Thanks,
Dan
Is it possible to put a stronger spring in an aftermarket BOV to keep it closed while idleing? Would this cure the stumbling and possibly dying idle?
Thanks,
Dan
05-19-2002, 02:34 PM
#9
Race Director
Hmm, yes and no. The stumbling and dying idle right after you let off the gas when you vent your air to the atmosphere is caused by improper air-fuel mixtures. There's a certain volume of air that flows past your AFM/MAF sensor and that volume is used by the computer to inject the proper amount of fuel. If you then dump that air out on the way into the engine, that same amount of fuel will still be injected anyway, but for a lower volume of air. Thus your mixture will be too rich, your idle will drop further than you want, and it may not recover and stall. The only way to keep the air-fuel ratio correct is to keep that air in the engine.
05-19-2002, 03:43 PM
#10
If I am doing the exchange rate for New Zealand correctly, the AFM Link and the Tuning module is around $200US. I will drop them a Email and confirm this.
Not a bad price for complete control of your AFR. Did anyone look at the Link Turbo module? It controls the timing and boost.
Not a bad price for complete control of your AFR. Did anyone look at the Link Turbo module? It controls the timing and boost.
05-19-2002, 06:11 PM
#11
Got a responce back from England! I thought they were in New Zealand... not much help.
Dear Sir,
We are not in a position to assist your situation from England. Please
consult the Link Electro Systems distributor in the US.
regards
BR Developments
Here is a US link
<a href="http://www.link-electro.co.nz/home.html" target="_blank">Link US </a>
Dear Sir,
We are not in a position to assist your situation from England. Please
consult the Link Electro Systems distributor in the US.
regards
BR Developments
Here is a US link
<a href="http://www.link-electro.co.nz/home.html" target="_blank">Link US </a>
05-20-2002, 01:52 AM
#12
Three Wheelin'
Hey Danno,
you said if you had to do it over again you go to an EFI, then you mention the apexi; SO would you rather have the MAP and the apexi VS the MAF??
Kokeln uses the stock flapper with the set up which is supposed to give 415??hp. This is one of the reasons i havent jumped on the MAF bandwagon.
but then systems like motec and haltech arent exactly a bargain and since this is just my street/traveling car, i dont think it will be needed.
But if I dont ( or you didnt) go with the MAF and/or the aftermarket EFI(atleast the expensive ones) what would you do?
Im up to experimenting <img src="graemlins/jumper.gif" border="0" alt="[jumper]" />
you said if you had to do it over again you go to an EFI, then you mention the apexi; SO would you rather have the MAP and the apexi VS the MAF??
Kokeln uses the stock flapper with the set up which is supposed to give 415??hp. This is one of the reasons i havent jumped on the MAF bandwagon.
but then systems like motec and haltech arent exactly a bargain and since this is just my street/traveling car, i dont think it will be needed.
But if I dont ( or you didnt) go with the MAF and/or the aftermarket EFI(atleast the expensive ones) what would you do?
Im up to experimenting <img src="graemlins/jumper.gif" border="0" alt="[jumper]" />
05-20-2002, 02:58 AM
#13
Race Director
"you said if you had to do it over again you go to an EFI, then you mention the apexi; SO would you rather have the MAP and the apexi VS the MAF??"
Actually, I mixed up a couple of comparisons there with the 240sx example. It already comes stock with a MAF sensor and the Apexi S-AFC simply piggybacks on to massage the air-mass signal. I was really making a comparison between the ARC2 and S-AFC in regards to piggyback-controlling a MAF sensor.
"Kokeln uses the stock flapper with the set up which is supposed to give 415??hp. This is one of the reasons i havent jumped on the MAF bandwagon.
but then systems like motec and haltech arent exactly a bargain and since this is just my street/traveling car, i dont think it will be needed."
This was mentioned a couple of times these past weeks. It's the fact that the air-flow signal is ignored by the DME under high-RPM/full-throttle conditions anyway. It simply uses a look-up table of RPM vs. injector-duty cycle.
That's because things would really get confusing in a 415hp car with the stock AFM. If you monitor the AFM, you'll find that it will max out with a clipped signal at 4.95v or such from 3500rpm onwards! Not much use there...
This ignored air-flow signal is also why MAF kits have minimal benefits over the AFM when parts are taken individually. Most of the benefits in MAF kits, I assert, are from the free-flow intakes with K&N filter, higher-boost from upgraded turbos, and higher boost-levels from upgraded controllers and more fuel from custom chips that happen to accompany a MAF sensor upgrade most of the time. You may notice that with MAF kits, every time you adjust your boost (change flow patterns) that you have to adjust your full-load fuel-maps?
This is why the aftermarket EFI systems go with a MAP sensor. They can continously compute actual air-flow conditions in real-times by sensing manifold-pressure and calculating an air-mass with RPM and air-temp data. Then an appropriate amount of fuel can be dispensed to match that air-mass. If you change boost-levels, add different air-cleaners or exhaust, you won't have to change your fuel-maps because the extra flow is automatically sensed.
"But if I dont ( or you didnt) go with the MAF and/or the aftermarket EFI(atleast the expensive ones) what would you do?
Im up to experimenting "
Ideally, I would still go with an aftermaket EFI as the first upgrade. Simply because I know I will never stop upgrading and the EFI system is probably the only thing that will be carried over with each successive upgrade.
But as an alternative to the $tandard MAF upgrades, I would test out the Link ElectroSystems AFM-link product along with a GM MAP sensor and keep the stock DME.
Actually, I mixed up a couple of comparisons there with the 240sx example. It already comes stock with a MAF sensor and the Apexi S-AFC simply piggybacks on to massage the air-mass signal. I was really making a comparison between the ARC2 and S-AFC in regards to piggyback-controlling a MAF sensor.
"Kokeln uses the stock flapper with the set up which is supposed to give 415??hp. This is one of the reasons i havent jumped on the MAF bandwagon.
but then systems like motec and haltech arent exactly a bargain and since this is just my street/traveling car, i dont think it will be needed."
This was mentioned a couple of times these past weeks. It's the fact that the air-flow signal is ignored by the DME under high-RPM/full-throttle conditions anyway. It simply uses a look-up table of RPM vs. injector-duty cycle.
That's because things would really get confusing in a 415hp car with the stock AFM. If you monitor the AFM, you'll find that it will max out with a clipped signal at 4.95v or such from 3500rpm onwards! Not much use there...
This ignored air-flow signal is also why MAF kits have minimal benefits over the AFM when parts are taken individually. Most of the benefits in MAF kits, I assert, are from the free-flow intakes with K&N filter, higher-boost from upgraded turbos, and higher boost-levels from upgraded controllers and more fuel from custom chips that happen to accompany a MAF sensor upgrade most of the time. You may notice that with MAF kits, every time you adjust your boost (change flow patterns) that you have to adjust your full-load fuel-maps?
This is why the aftermarket EFI systems go with a MAP sensor. They can continously compute actual air-flow conditions in real-times by sensing manifold-pressure and calculating an air-mass with RPM and air-temp data. Then an appropriate amount of fuel can be dispensed to match that air-mass. If you change boost-levels, add different air-cleaners or exhaust, you won't have to change your fuel-maps because the extra flow is automatically sensed.
"But if I dont ( or you didnt) go with the MAF and/or the aftermarket EFI(atleast the expensive ones) what would you do?
Im up to experimenting "
Ideally, I would still go with an aftermaket EFI as the first upgrade. Simply because I know I will never stop upgrading and the EFI system is probably the only thing that will be carried over with each successive upgrade.
But as an alternative to the $tandard MAF upgrades, I would test out the Link ElectroSystems AFM-link product along with a GM MAP sensor and keep the stock DME.
05-20-2002, 03:59 PM
#14
Advanced
Join Date: May 2001
Location: seattle, wa
Posts: 72
Likes: 0
Received 0 Likes
on
0 Posts
This thing about the air-flow signal being ignored is really interesting. Does this mean that all air/fuel controllers that intercept and "massage" the AFM signal are only good to about 3500rpm on our cars?
It seems that the ARC, S-AFC, and even the AFM-link would not work in the higher rpms using the stock DME...or am I missing something, do these systems somehow keep the DME from ignoring the air-flow signal?
It seems that the ARC, S-AFC, and even the AFM-link would not work in the higher rpms using the stock DME...or am I missing something, do these systems somehow keep the DME from ignoring the air-flow signal?
05-26-2002, 05:54 AM
#15
Three Wheelin'
Join Date: Feb 2002
Location: Arlington, TX
Posts: 1,493
Likes: 0
Received 0 Likes
on
0 Posts
Danno,
Can you help explain this, because I don't see how the AFM Link is any better than the S-AFC for tuning the midrange RPM, but I'd still need something for WOT, which is when I'm gonna want that HP and nice AFR anyway.
Can you help explain this, because I don't see how the AFM Link is any better than the S-AFC for tuning the midrange RPM, but I'd still need something for WOT, which is when I'm gonna want that HP and nice AFR anyway.