WTF?: Legacy BC5 Cuts out @ 9psi

[THUNDA]

Heya guys, sorry just thought it would be better suited to post here

Basically the problem is once the boost rises to 9-10psi it cuts

it feels like the same cut that you get when you overboost to 18psi ~ and the factory ecu cuts the fuel

anyone know what the problem could be? boost solenoid? (have tried with it unplugged also and it doesnt make a difference)

the car has just had a full service, 4 new spark plugs and 1 brand new coil pack installed due to mis firing and car is running mint other than it boost cutting at 9-10psi

help!

0210666306 or just post on here

[BC5RA]

Do you have a check engine light?

Possibly in limp mode.

[THUNDA]

Yeah but what plugs do i plug in for it to flash? black plugs or green plugs? and do i plug them both in, ? limp mode? maybe i should reset my ecu tonight?

[BC5RA]

Don't bother, some may disagree but disconnect your negative battery terminal and leave it for ten minutes and reconnect.

It's not strictly speaking the correct way of resetting but it will get rid of your check engine light and fault.

[BC5RA]

Limp mode from my experience hits a soft limiter and will run about 9psi and 4500-5000rpm.

This was with my Series 2 RS, it could be limp mode with the Series 1 will manifest itself differently.

[THUNDA]

oh, i disconnected both my battery terminals and pumped the brake a few times and was going to leave it overnight, should i put the terminals back on then remove the negitive one and do it your way or will my way work?

[BC5RA]

Connect them up and start it now if you can be bothered.

[THUNDA]

connected them in the morning, no difference, still cutting @ 9psi, my boss recons the knocking sensor would have fucked out, what do you guys recon? the engine doesnt knock at all its a very tight engine because of its low kms and good service history

[Koom]

 THUNDA said:

it feels like the same cut that you get when you overboost to 18psi ~ and the factory ecu cuts the fuel

Are you still on a factory ECU or is it chipped?

From memory the factory boost cut on the series 1 BC5 is around ~12-13 psi isn't it?

[THUNDA]

Nah, 18psi ish

[THUNDA]

Factory ecu

But not running factory boost controll solenoid at all, like its not even in the car, but never had any problems before, it hasnt been in the car for around 2months

Just spoke to a guy at subaru parts connection he said its most likely to be the knock sensor or the boost solenoid, i've been reading up about knocking sensor problems all morning, and it sounds like a match, man i really should be doing some work, but i just wanna get this fixed ay >_<

[Bazza-NZ]

 THUNDA said:

Nah, 18psi ish

Its 15psi isn't it? well mine cuts out at exactly 15psi

[THUNDA]

Oh ok, 15 sounds about right, i had the boost gauge reading off the wrong vacuum line when i got that reading, havnt hit boost cut up untill a few days ago when this 9psi boost cut shit started

[BC5RA]

It could be a faulty knock sensor.

If your getting a code then you should check it.

[THUNDA]

yup, getting code 22

its weird, now when i put my foot right to the floor (i like, NEVER, do this) it boosts 14ish but only on 3cylinders, i.e; feels like its fouling on the amount of fuel getting pushed in there but still going - then it will boost cut after a few seconds

o well, ill order a new knock sensor on monday, unless i can source one tomorrow

bah, what a hassle

[BC5RA]

Code 22 - Knock sensor.

Seriously these cars are OLD; many things will contribute to poor running.

[THUNDA]

o yup sweet thanks for that

you dont have a spare sensor laying around do you?

its weird even though these cars were made on 1989 and are old, they just dont feel old lol

maybe its just because im stuck in the 1988-92 era (i love heaps of cars made in this year, s13 is probly one of my fav cars to drive then legacy definately )

[BC5RA]

No i don't sorry.

Maybe you should take a trip to pick a part, no point in spending money on new part's if your selling it.

[Bazza-NZ]

 THUNDA said:

o yup sweet thanks for that

you dont have a spare sensor laying around do you?

its weird even though these cars were made on 1989 and are old, they just dont feel old lol

maybe its just because im stuck in the 1988-92 era (i love heaps of cars made in this year, s13 is probly one of my fav cars to drive then legacy definately )

If twin turbo ones fit then i have one sitting around, otherwise pick a part would be your best bet,

[THUNDA]

Just paid $90 for 2 knock sensors, both from subaru parts connection, both have warrenties, tried both of them, neither of them make a differnce, OMFG ARGGGGG

i guess next bet is to change air flow meter?

argg... someone wanted to buy my car for 3k today but its not worth jack shit if its not fixed

its weird it fouls @ 9psi then cuts like 1 second later, i can hold boost between 5-8psi then as soon as it hits 9psi it cuts. @#$#%@#%@#%@#

[Guest]

not sure if you need to but did u reset ecu after trying the sensors?? if you had cell 22 come up then there is definatly a problem there...I wouldnt trust buying second hand knock sensors most the time they give the wrong one...I went through the same hassle of trying all sorts of knock sensors from subits, waiuku car spares and trade me...until I just went brand new from wingers and it went allgood after that. They are abit overpriced i think it cost me $120 back then last year...wat did the plug on the knock sensors look like? were they the same as the plug from your original one? not sure if tht matters but the guy from wingers pointed that out to me when I bought mine.

[THUNDA]

yeah but im not getting a code now, and yes have tried to reset my ecu

yes both knock sensors had identical plugs to mine and plugged straight in.

thats why i bought 2 as to assure there would not be any problems as the car is ment to be sold today

[BC5RA]

If you've not replaced the AFM then get a hold of a mates and test it.

[Guest]

+1