SF5 with PFC problem
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Author:  peruccy [ Mon Jul 17, 2017 6:01 am ]
Post subject:  SF5 with PFC problem


I don't know what else to do, so I'm hoping you fellas could help. I've searched countless forums and topics, but can't seem to get my car to work with the used PFC, which I got a week ago. I'll try to give as much info as possible...

Spec of my SF5 '99 EJ205:
- Stock ECU (now replaced with PFC - model GC8F 020-0683)
- Apexi SAFC2 (now removed)
- HKS FCD (now removed)
- Bee-R Revlimiter (now removed)
- Innovate LC-2 Wideband Kit
- Hybrid TD05H-20G with Adjustable Wastegate Actuator
- Blitz Dual SBC @ 1.4bar (soon removed - waiting on the boost harness for the pfc, so It will control boost)
- JECS 550cc
- Blitz SUS Filter
- Custom 3" Downpipe
- CXRacing Chargecooler Kit with 1200cc EWP
- 70mm Silicone Intake Pipe

Reason for going to PFC, apart from the fact I can tune it myself, was because I maxed my stock MAF. It could not read any more flow beyond 5000rpm. That was because I had to fool my MAF with both HKS FCD, and SAFC2. So it was maxed out @ 1.4bar above 5000rpm.

I set my base map like so:
- Lambda control off
- Boost control off
- Ignition -4‘ on the whole map
- Injectors @ 80% (440cc vs. 550cc, right?), and Latency @ 0.08ms (stock are 0.80ms, and JECS are 0.71ms, right?)
- Revlimit from 6300 - 7000rpm
- Air filter option 2 (Apexi intake - good choice for my setup - Blitz SUS + stock MAF?)
- Rest of the settings I left alone

So, I've bought the PFC from a guy which had it in his WRX. Firstly, I only switched pins 5 - 6 in the B136 connector, but the car wouldn't start. I didn't know at the time, that I also need to move pin 1 - 21 in the B134 connector, because my car has an immobilizer. OK, switched the pins, tried again, and nothing. Car started up for a second, or how much fuel was in the rail, and stalled. Same as before the switch. So I installed my stock ECU, switched back all three pins, and presto, first time start! I remove the ECU, and plug in the PFC. Again switch over three pins, and it actually started!
So, I went through the idle learning process. Car idled flawlessly, and blip of the throttle was much nicer, since I was not fooling my MAF anymore. Then I turned the boost all the way down to 0.66bar (lowest boost for the bright blue wastegate spring), and went for a drive. Throttle response was much better, just with the base map. I drove it sensibly, BUT... It stalled in a roundabout, and it would not turn over. I've been diagnosing the problem this whole week, but it just does not prime the fuel pump. I've gone though the original subaru forester 1999 repair manual. I've checked every voltage, resistance, and connection to-from the ECU - for the 12V, grounds, fuel pump, fuel pump relay, and main relay. Both ECU's have the same input/output. Car starts fine with the stock ECU, and it won't with the PFC. I've tried to start it without the immo box plugged in, and also the antenna, and with one or both. Does not make any difference. I've measured what happens at pin 1 with stock ECU, and pin 21 with PFC:
- Stock ECU has nothing when IGN OFF. With IGN ON, it gets 12V until fuel pump is priming (~2s), then voltage drops to 0, and it switches to ~0.3ohm resistance, and when the car is starting, resistance goes to ~155ohm, and stays there while idling.
- PFC has nothing when IGN OFF. With IGN ON, it gets 12V, but the fuel pump does not prime! It does not switch to resistance, it stays @ 12V, even when starting, and when it starts up briefly, it still shows 12V, and then it stalls.

Is the PFC bad? Or am I missing something here... I'm pretty sure my wiring is good, or is there something else different between WRX/SF5 wiring? Because I was driving it a few days ago, and it idled for like half an hour, and all was good until 5mins of driving. Is this my immo acting up? BTW...how is it even possible, that the PFC was searching for my key code, while driving?

Any help would be much appreciated!

Author:  peruccy [ Mon Jul 17, 2017 8:15 pm ]
Post subject:  Re: SF5 with PFC problem

Here are some pics:
From C32 goes 12V to pin 2 of main relay. I've measured this relay - Pin 2 12V, pin 1 earth, and between pin 3-5 & 4-6 there should be max 10ohm resistance. I didn't get those values. But why would the car start with stock ECU, and not with PFC?

From pin 1/21 goes 12V to pin 3 of fuel pump relay. When pump is priming, it has 12V for ~2s, then it switches to resistance. With PFC it does not switch to resistance, it shows 12V all the time, that is why my fuel pump is not priming...

Here is a diagram for injectors. If I remove my immo box with stock ECU, car starts for ~2s, then the ECU shuts down injectors...

PFC does not show any errors in commander

Fuel pump relay




Main relay

I've triple checked before purchase, if I have the correct PFC for my car. I think I do:

And this is the effing immo box! Unfortunately, I don't have a diagram for this



I will also write to Apexi-USA, if they will be able to help...

Author:  peruccy [ Sat Jul 22, 2017 7:09 am ]
Post subject:  Re: SF5 with PFC problem

Still can't get my fuel pump to prime! I've tried used but 100% working main relay and fuel pump relay = same. I also tried a brand new recharged to max battery = same. So I compared measurements between stock ecu and pfc for injectors:
- Stock ecu connection between B136 pin 9 (positive) - B134 pin 18/25/31/32 (injectors) = ign off 11ohm / ign on 12ohm / both times against ground
- PFC connection between B136 pin 9 - B134 pin 18/25/31/32 = ign off 12ohm / ign on 11ohm / both times against ground
- Resistance is a bit higher than it should be as in the book

- Stock ecu B134 pin 18/25/31/32 - to ground = ign off 0,36ohm / ign on 0,85ohm and against ground
- Pfc B134 pin 18/25/31/32 - to ground = ign off 0,50ohm / ign on 0,85ohm and against ground
- Again, resistance is a bit higher than it should be as in the book

- Stock ecu B134 pin 18/25/31/32 - led lamp = ign off nothing / ign on negative is on and same when cranking
- Pfc B134 pin 18/25/31/32 - led lamp = ign off nothing / ign on negative is on and same when cranking

- Stock ecu B134 pin 18/25/31/32 - positive = ign off 0,46V / ign on 12V
- Pfc B134 pin 18/25/31/32 - positive = ign off 0,01V / ign on 12V

Tomorrow, I will re-wire my injectors. If that won't help, I will try to measure injector drivers in the ecu. And if that turns out ok, then I'm at a loss... Only other thing would be, I'm missing a wire somewhere. Thing is, I had HKS FCD + BeeR Revlimiter + Apexi SAFC2 (I think there were 14 wires all together), wired to my ECU harness. I removed them, fixed my wiring, and installed PFC. It is possible, I forgot a wire somewhere...

Is anyone willing to take a pic of their MY99 WRX ecu pinouts? At least 20cm of harness, so it will be visible which wires are connected. That would be mega!


Author:  peruccy [ Sat Jul 22, 2017 7:21 am ]
Post subject:  Re: SF5 with PFC problem

Also, I've compared MY99 WRX pinout, and MY99 SF5 pinout. Can someone explain, why on one side of the manual it says B136 pin 1 (for immo), and pin 2 (without immo) is ground for control systems. But on the other side is says B136 pin 1 is MAF signal, and pin 21 is Lambda signal?
MY99 SF5 Pinout 1/2

MY99 SF5 Pinout 2/2

MY99 WRX Pinout 1/2

MY99 WRX Pinout 2/2


Author:  peruccy [ Sat Jul 29, 2017 8:02 am ]
Post subject:  Re: SF5 with PFC problem

After many many hours, and a help from an electrician, we found the problem. First problem was a bad injector driver (yPA1556AH), which I replaced. The second problem is, that there is a constant connection between A1 and A21 on the board (pin 1 & 21 in B134). We tested the stock ECU, and it has two paths for A1 (if code present or not), and no paths for A21. They are not connected, and everything works fine. Power for pin 3 of fuel pump relay goes against ground, as does power for injectors for pin C8 & C9 of B136. But in PFC, both A1 and A21 are connected, and the path ends with the transistor. We can't see where does the path go... We tested all the diodes around transistors, and all are good. Anyone know the path for A1 & A21 in PFC board?

Something else is fried, we just can't seem to find it...

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