93 Single Turbo Legacy Issue

[THUNDA]

Heya guys

am having a bit of trouble with my legacy

its a nz new single turbo ej20 manual wagon.

I recently have installed a boost controller (hehe)

it is just a bleed type, i.e; bleeds pressure off wastegate actuator to trick the system into thinking there is less pressure in the intake manifold.

when i turn the boost up to 14psi, the car boosts perfectly most of the time, but every now and then it misses during boost at about 5000rpm, then carries on as normal.

the miss is like its miss firing due to lack of spark, but could it be lack of fuel?

because when it misses a cloud of black smoke comes out the back

it never misses on standard boost though

and sometimes takes ages to start? but not when its just been turned off then back on.

car was serviced 1500kms ago, but it doesnt state whether or not the spark plugs were replaced, but id assume they were not replaced seeing as though the reccomended plugs cost $20ish each

[wildturkey]

 THUNDA said:

Heya guys

am having a bit of trouble with my legacy

its a nz new single turbo ej20 manual wagon.

I recently have installed a boost controller (hehe)

it is just a bleed type, i.e; bleeds pressure off wastegate actuator to trick the system into thinking there is less pressure in the intake manifold.

when i turn the boost up to 14psi, the car boosts perfectly most of the time, but every now and then it misses during boost at about 5000rpm, then carries on as normal.

the miss is like its miss firing due to lack of spark, but could it be lack of fuel?

because when it misses a cloud of black smoke comes out the back

it never misses on standard boost though

and sometimes takes ages to start? but not when its just been turned off then back on.

car was serviced 1500kms ago, but it doesnt state whether or not the spark plugs were replaced, but id assume they were not replaced seeing as though the reccomended plugs cost $20ish each

What boost were u running b4 u installed the boost tap?......at 14 psi u might be getting close to factory fuel/boost cut threshold. R u running standard ecu?.........if you turn the boost down to say 13psi or 12 psi.....do u still get the same prob?

[Wiretap]

Sounds like it could be detonation, either that or you're colliding with boostcut due to creep... either way, pull it back a little unless you want cornflakes.

[BC5RA]

There could be a number of reasons for this issue;

Hows your AFM? they don't need to throw a code to have issues.

Are you still running the standard coils, How does it run when its cold?

Boost leak can cause this as well, You should trace your intake path to throttle body and check for cracks, also check you up pipe, even a bad batch of fuel.

 Wiretap said:

Sounds like it could be detonation, either that or you're colliding with boostcut due to creep... either way, pull it back a little unless you want cornflakes.

Care to explain that?

[Hailz]

Chances are your computers sensing more boost than whats normal and cannot lower it buy using the wastgate because your boost tap is in the line now so its cutting spark to try and drop it down hence the puff of black smoke (un burnt fuel), it would probably have put it in limp mode now because of it hence your slower start ups, a mates wrx done the exact same thing at anything over 13psi, all I can say is that your best bet is to, A- Lower the boost your running B- remove the tap completely and put up with slightly less grunt than before or C- get an aftermarket computer setup of some sort to override the high boost signal that your current computers getting.

A simple equation you can do is,

Higher boost + no mods to support it = rattle rattle bang boom!

Might pay to reset the computer and see what that does too.

[Andrew NR]

I'm running 12psi in my BF5 GT quite happily. Boost cut is at about 15psi, I found that out first hand when I installed my boost controller wrong and it free boosted. Are you running the stock turbo? if so it may be running out of puff after 5000rpm and that's why it seems fine after 5000rpm.

[ReubenH]

Well, for a gen 1, that's awefully close to boost cut. Could be just hitting cut, then the boost will taper off in the higher revs. Just a thought.

[THUNDA]

it runs fine when its cold and starts sweet it just takes awhile to turn over sometimes (longest is like 4-5seconds)

boost cut at 14psi? ive had about 6 or 7 of these old legacys, i do the same things everytime and none of them have run like this, these cars dont just go "BOOM" if you turn the boost up, hell you guys are making these cars sound like they dont have strong engines! if only you all knew how much thrashing i have dealt to these cars (lets not dance around it) and NEVER had one blow up on me, maybe its because i never fuck around when it comes to servicing the car.

runs sweet at 10psi, as soon as it goes above that it starts to muck around.

[THUNDA]

also sometimes the car smells like petrol (when running), i.e; not all of the fuel is being burnt.

standard coils as far as i know but its likely they have been changed considering the car has done 250,00kms

Anyone got a spare green sticker afm they wanna lend me or sell me?

[Drunkenmonkey]

where in auck are you i got my gen 1 it likes 11 psi but hits cut 12-13 and becomes unhappy

[THUNDA]

didnt you come to my house with shale to pick up that GT?

maybe it was someone else

Central auckland area

[THUNDA]

fuel filter has been recently replaced (its shiney...)

and fuel pump has a good earth and full power (not really any other way to check if its functioning perfectly but wouldnt be surprised due to its age if its failing)

is it true you can just resoilder the joints in your afm (circuit board) and it will run like new again? have heard this from many people now

[Hailz]

 CUDDAS said:

HAS anyone used CRC AFM cleaner?

Yeap works a treat!! I've used it in all my injected cars and definately makes a difference, I use it on the Legacy about every 6 months as I've got a oiled K&N in there and it does run smoother after you've done it.

[Drunkenmonkey]

nup wasnt me and yeha i have re solder the joins and it worked sweet but the guy who brought it off me did have an advert up asking for another one lol