Thanks for reading!

I've been having an issue with my PFC, tuned at a shop with datalogit. It was fine for about a month but now I am intermittantly getting situations where the car will just die when driving, as well when this happens it will not start for 10-15 min but will turn over just fine. It seems to turn over and get good ignition a couple times and then turn off again. Throttle position has no effect when I try to start the car after this happens. The car will also very randomly have this starting issue after I go to start it up when it's warm - for example after turning it off to put gas in it. It never has an issue starting in the mornings or any other time it's been sitting for awhile.

It runs perfectly when it's running and runs completely fine with the stock ecu.

Anyone have any ideas of where I should start in terms of looking for a solution to this? I have the datalogit hardware and access to a laptop and could run the program but I don't know what I'm doing with the values and would hate to accidentally wipe the tune.

I have physically inspected the PFC board and there is nothing obvious like a blown capacitor or the like. The shop has had no issues tuning it so I can't believe there would be something wrong with the circuitry. I'm trying to make sure there isn't something wrong with a sensor somewhere before I have them look at the PFC again about this issue.

Car Info:

MY98 STi Type-RA V-Ltd
EJ20K (completely stock) - the PFC is to tune for Canadian gas as I was knocking a bit under load with the stock ECU.

Can you hear if the fuel pump is running when the car is having issues?

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MY00 WRX. 89 Prelude. 99 CRV

I think I can still hear the pump clicking and the initial whirr, yes.

Make sure you have a good 12v and ground to the ecu. Have seen a few cut out. Iv just wired a relay in and has solved the problem

could also be a fuel pump controller if you have a 2004+ car

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Marti


Car: C Red S13 Silvia 2.3l 400+rwhp-SOLD
Daily ae82 4age corolla (light mods)-Sold
Daily:SWB GQ Patrol
Will be a 03-04 STI next

Pfc's cutting out on Subaru's? not likely..... on Skylines with PFC D-jetro's perhaps?

And he has a 98 as he said....

O.p: check the pfc's board for corrosion where the plug pins meet the mainboard - GC8's are prone to leaking water on to the Ecu which gets all kinds of gremlins started.

Use some aerosol contact cleaner on the main board, the ECu pins & Plugs - Also do the main engine harness plugs under the hood.

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Thank you - I will.

So, to confirm. You have refitted the stock ECU for a long term test and the fault is gone? (other than the detonation)

It sounds like possibly a dry solder in the PFC ECU board or possibly one of the pins in the ECU is not connecting reliably in the socket where it plug in to the 3 yellow connectors?

Another common fault is the fuel pump plug under the rear seat cushion (right hand side)
It's usually partially covered with black tape, 6 pin connector with 5 wires. Check it's not melted. Although if this was faulty it would still be evident with the other ECU.

Another idea I use when diagnosing intermittent faults like yours is to rig up a 12 volt lamp to the fuel pump power and earth at the back seat connector. Leave it in a visible location. When the car cuts out you can easily inspect the power supply is good or bad.

Thanks for this reply!

I have fitted the stock ECU back and have had no issues. I had the stock ECU on for months before the PFC so I'm not too worried about detonation when it's not being tracked.

It has occurred to me that it could be a loose connection, but I don't understand why it would right itself when I haven't physically done anything by the ECU itself. I've also sat with the car idling and pulled on all the wires ETC trying to reproduce the fault - haven't been able to.

I took a look at the board and didn't notice anything unusual (on the PFC). I'll have a hardware engineer friend take a look at it as well.

That's a fantastic idea with the check lamp - I'll rig it up. I agree it would be suspect for it to not be giving me the same fault with the stock ECU.

Thanks again for the great ideas.

Take me for a spin in your car next time I'm in Vancouver, I love that city!

Yes!!

Japadog <3.

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