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Old 09-12-2002, 05:53 AM   #1
Scooby Newbie
Member#: 24458
Join Date: Sep 2002
Location: Scottsdale
Default Apexi questions, please help

ok i have a 02 wrx and looking to install the AVC-R boost controler, i want to know if i should atempt this by myself or seek a shops help, if it can be done ill do it myself but i want to find some specific install guide for the Wrx that someone else used and could send me the link, i did go to apexi-site and downloaded all the instructions but i want it from someone else who knows,

Second i have a S-AFC do you think it is needed if i will be only running boost contol,bov,intake, & exhaust? and ill need the instructions if anyone has them for a WRX because again the stuff on the apexi site is alot of latan

third is it possible to run the apexi turbo timer (the 1 with O2 sensor and A/F meter) on a WRX that has the upgraded factory alarm? if it can be done let me know if there are any D I Y's for it or if anyone else has the experience with that unit

oh is the 1000 mile break-in for real or can i get on it sometimes?

and always any comments are a must, good or bad
if you dont like a part i mentioned tell me why so i can see whats best for me, so i can learn

Thanks JON
(im new to "WRXing") picked her up thursday allready put 700 miles on her almost done with break-in Love the car like my girlfriend.
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Old 09-12-2002, 06:47 AM   #2
Scooby Specialist
Member#: 66
Join Date: Jul 1999
Location: Vancouver, British Columbia, C
2002 Impreza WRX
Britney Edition


Dont use the apexi diagram. Aparently there is 1 error there.

Follow these instructions for ecu wiring. http://teamhelluvafast.tripod.com/

I installed the avcr myself. Wasnt too difficult. Hardest thing was getting the sensors through the firewall grommet. I probably wouldnt try installing it myself unless i had a decent knowledge of electronics and how to wire up the pressure sensor and boost solenoid.

You can find more info on the avcr install here. Just do a simple search and you can find all of this. http://forums.nasioc.com/forums/sear...der=descending

1000 mile break in period sounds about right =|
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Old 09-12-2002, 06:58 AM   #3
Scooby Newbie
Member#: 18057
Join Date: Apr 2002
Location: Sydney Australia
2001 WRX


I think you'll need some kind of ECU interceptor or replacement ECU with those mods if you want the most out of them.
This model WRX doesn't lap up the mods like the older shape WRX (aus). They certainly make an improvement, but you will find that the ECU works against the mods a little, and runs pig rich too (closed loop boost control is probably a good reason why just throwing a big exhaust on doesn't do what it did with the older WRXs.. they showed a boost increase with this, the MY02- doesn't show much of an increase).

Have a look at this article:

and see what small improvements the various bolt ons made, and what a large improvement the unichip made.
Be a little wary that this may be a bit of a "commercial" for uni-chip & the *full* APS kit... but still, I generally believe it after seeing what a kit based PIC Air Fuel meter displays as the mixture on my car at full throttle (<10.5:1... but this reading taken off the narrowband sensor is probably not the most accurate!)

I am running S-AFC (did this months after 3" MRT, resanatorectomy with new in-guard pipe, boost tweaked) and I must say, just lopping off 7-10% fuel has made a huge difference. Aus may be a little different to the US (tuned for different fuel), but I still think that your cars run VERY rich with just a few mods, and thus Unichip/S-AFC/UTEC/etc are good improvements as they reduce the fuel mixtures to around 11.5-12.5:1 which is ideal for 15-17psi boost levels.

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Old 09-18-2002, 09:51 PM   #4
Scooby Specialist
Member#: 7962
Join Date: Jul 2001
Chapter/Region: MWSOC
Location: Louisville KY
08 335i TwinTurbo
PSM 02WRX, 97 Dipped CRV

Default ...

Know any links for a S-AFC install?????

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Old 09-19-2002, 01:04 AM   #5
Scooby Newbie
Member#: 18057
Join Date: Apr 2002
Location: Sydney Australia
2001 WRX

Default S-AFC Install

It is fairly easy to do.
It has a loom that connects all down at the ECU.
The following are the connectors that are bridged/tapped on the existing ECU loom:
Ground (power)
Ground (sensors)
Throttle Pos Sens
The MAF wire is chopped and has 2 connections, one into the S-AFC loom, and one out of the S-AFC loom into the ECU MAF in.

There is another trick to get a Air/Fuel/O2 voltage reading with the S-AFC.. it is called "the blue wire mod". Connect the unused (only used with cars with 2 MAFs) blue wire of the S-AFC to pin B-17(white) on the ECU loom, and you can get a very accurate voltage readout coming off the rear O2 sensor in the "Sensor Check" screen of the S-AFC. Just make sure in the settings window you choose single MAF, or else you are going to average your O2 sensor and MAF sensor readouts as the MAF signal and I can't imagine the car would like that too much!

All the wiring diagrams, installation instructions etc are on the apexi-usa website, here is the MY02 Subaru diagram (among others): http://www.apexi-usa.com/productdocu...afc_udpate.pdf

The only change that I did was wire one of the S-AFC grounds (the wire that the instructs say "must be mounted closer to the ECU than the power gnd") onto the sensor ground on the ECU B19, Red/Black, referenced here: http://www.northursalia.com/m...ng/wrxpin.html . When it was wired to the S-AFC documented ground (about 1 inch from the ECU), I had the TPS jumping around a bit (and all the other readings in the sensor check window). The S-AFC seems to work out what 0% throttle and 100% throttle is by putting the range of voltages it gets into memory, so what was happening was, I would be driving with my foot partially on the throttle, and the S-AFC would say "0% Throttle"! When I moved this ground, now the TPS is perfect. The reason for this problem I believe is that the Subaru grounding system isn't the best (and YES, I have done a bit of a grounding mod, adding a large ground from battery to chassis, and left side manifold to battery), and the ECU main ground has small voltage drops on it when firing solenoids/coils/injectors (sounds like the grounding mod thread should also talk about improving the ground to the ECU ) These voltage drops don't impact devices that only care about getting a +12v pulse, but are major for trying to read small voltages off the TPS, O2 etc. It was actually my LED O2 meter that I re-wired to the S-AFC earthing point when installing this S-AFC that pinpointed what was causing this prob (I thought maybe the S-AFC registers 0% for small throttle openings due to poor accuracy or something..), because the LED 02 meter was jumping all over the place like crazy compared to where I had it earthed before (the Subaru dash clock... I wanted to move it from here, because turning on the lights would drop the readout by 3 LEDs!). and NO, I am not talking about its "normal" behaviour of moving up and down while doing normal driving, this normal behaviour is a smooth transition between rich and lean, not rapid and random jumping that was occurring when on the ECU power earth.
Summary of this paragraph: The ECU Sensor Ground, B19, is perfect for grounding the S-AFC (sensor wire only!) and the LED Air/Fuel Meter ground(different project to S-AFC...).

The only real problem with the S-AFC is that it has a "Low throttle position" map and a "High Throttle Position" map, and it interpolates anything in between. So if you have a situation where you want to add fuel with low throttle (for some reason, the WRX runs extremely lean under low throttle positions in closed loop, but I don't think you can add fuel in this situation as the closed loop control works against it... I am still trying to add a bit, just to get the MAF readout tweaked), then take out fuel for higher throttle positions, you have to think about the ratio and how much difference there will be between the two throttle positions compared to if you leave the low throttle position at zero... look at the main pdf, it has a diagram explaining the interpolation.

Hope this helps, any more queries, I will only be too glad to answer.
p.s. I haven't had the S-AFC dyno'd yet, I am still trying to get my hands on a wide band Air/Fuel meter, to calibrate/verify what I am reading off the rear O2 sensor. I have knocked off 10% of fuel, and the rear O2 voltage still goes over 0.95v under WOT.
But it is a genuine LARGE improvement on the performance, much more improvement than my first mod of bolting up the MRT turbo back.

Last edited by tonymy01; 09-19-2002 at 01:13 AM.
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