SteveMy96wrx

Hi,

As above, I'm trying to trace an overboost issue with a import pre-facelift WRX wagon. The only mod is the Polar performance/ScoobyECU chip - everything else standard, new plugs, new coil packs, new lambda.

Overboost is occuring under heavy load.

Currently I'm looking at the restrictor pill as a possible cadidate - it's bore is 1.9mm, anyone know if this is correct or has it been drilled?

Many thanks!

joz8968

iTrader: (13)

1.9mm! I'm sure the OEM size is anywhere between 0.8-1.2mm (can't remember TBH). I suspect it HAS been drilled.

If so, then yeah, it will overboost with an oversized hole.

SteveMy96wrx

Hi there cheers for the reply. I suspect it has as well, the confusing thing is finding the exact sizes for each model since they vary.

I've just found a print out from the polar performance site (now down unfortunately) which suggests it should be 1.5mm - can anyone confirm the size for a JDM prefacelift wagon?

joz8968

iTrader: (13)

Do you know the 2-digit code of your car's ECU? You can check underneath the passenger footwell. That way, we'll know what the boost target is supposed to be then go from there... (FTR what's your gauge boosting to?)

BTW, you defo don't have a BCS-bypassing bleed valve or MBC fitted by a previous owner, do you?

SteveMy96wrx

Not that has been fitted since it was shipped to the UK! The boost target for the factory ECU was raised by the ScoobyECU chip, firmware is upgraded to Z4 and the listed boost target is 10.8 according to the polar performance bumf, though there's no guarantee ScoobyECU have tweaked the map to more.
FTR, going shopping for a boost gauge .. :-)

hpoolsteve

iTrader: (4)

Im sure it shoiuld be 1.2 mm as standard

joz8968

iTrader: (13)

Oops, only read the bit about the pill - didn't realise a ScoobyECU was fitted. Sorry.


Yeah, boost target is around 1.1bar ( I assume you meant 1.08 and not 10.8? ).

Re lack of boost gauge: are you hitting the "brickwall" fuel cut then, when under heavy load/WOT?

SteveMy96wrx

Cheers for that, now looking for a part number lol

joz8968

iTrader: (13)

That's what I thought too.

SteveMy96wrx

Hmm seems it IS standard? Good thread here:

https://www.scoobynet.com/technical-...locations.html

seems to suggest size should be 2mm

BOB RAWLE.....

MY93-96 ... 3 port solenoid 2.0mm restrictor fitted into the vent pipe between solenoid lower port and intake

MY97 (Euro) ... 2 port solenoid 1.2mm restrictor fitted between the turbo and the tee piece

MY97 (JDM) ... 2 port solenoid 0.9mm restrictor fitted between the turbo and the tee piece

MY98 (Euro) ... 2 port solenoid 1.2mm restrictor fitted between the turbo and the tee piece

MY98 WRX (JDM) ... 2 port solenoid 0.9mm restrictor fitted between the turbo and the tee piece

MY98 Sti 4 ... 3 port solenoid 1.5mm restrictor fitted between the turbo and the solenoid adjacent to the solenoid top port

MY99 (Euro) ... 2 port solenoid 1.2mm restrictor fitted between the turbo and the tee piece

MY99 (JDM) ... 2 port solenoid 0.9mm restrictor fitted between the turbo and the tee piece

MY00 (Euro) ... 2 port solenoid 1.2mm restrictor fitted between the turbo and the tee piece

MY00 (JDM) ... 2 port solenoid 0.9mm restrictor fitted between the turbo and the tee piece

MY01-05 (Euro) ... 2 port solenoid 1.2mm restrictor fitted between the turbo and the tee piece

MY01-05 STi ... 2 port solenoid 0.9mm restrictor fitted between the turbo and the tee piece

MY06/MY07 both WRX and Sti 2 port solenoid 0.9mm restrictor between turbo and tee piece

joz8968

iTrader: (13)

Ah, okay.

Test the w/g is functioning okay by temp. running a bit of vac pipe between it and the comp bleed nipple. It should boost to to around 0.5bar/7psi. If that checks out, return that back to normal... then reconnect the J1 resistor in the ECU so as to run the OEM map, rather than the ScoobyECU chip's one. If that boosts to the OEM target, then yeah, suspect the ScoobyECU chip to be at fault...

SteveMy96wrx

comp bleed nipple?

joz8968

iTrader: (13)

The little outlet port on the turbo's compressor cover.

It goes to the w/g via the boost control solenoid. When you carry out the above test you are simply bypassing the BCS's/ECU's control of the w/g.