scooby46

iTrader: (2)

I have an 360ish bhp v2 sti classic impreza. The boost is controlled by a avcr boost controller. The boost on setting 'A' is set to 1.4bar. On the weekend i relocated the boost solenoid in the engine bay and had to put some old vac hose on as the orignal hose wasnt long enough.

So i took the car for a spin and when i floored 2nd, 3rd and fourth i got an almighty boost and a loud whine from under the bonnet.I then looked at the AVCR and it showed that i hit 1.86bar! It shouldnt go any higher that 1.5 bar.

So i checked the hoses and found that one hat a split in so i replaced them all with band new pipes. Now when i take it out the boost is controlled (hits 1.4bar) but i get a violent jolt and the engine light flashes once! and that hits just over 1bar when it does that

Im not sure what it could be, some people said its boost creep, some say that i need the restrictor pill in the hoses, some say the baileys single piston dump valve is ****/fooked.

Any help would be greatful

cheers

scoobian

sounds like you've hosed it wrong or the hosing isnt up to thejob
go back to scratch, I rckon!

scooby46

iTrader: (2)

ive got the hoses the right way because i checked with my mapper. on the solenoid it goes;

com to actuator
no to compressor housing.

So i think that the hoses are all in the correct place now. But it still doing it.

scoobian

possibly the old hoses are bulging and upsetting the settings
or maybe the hoses are just too long now and thats interfering with the boost settings?

scooby46

iTrader: (2)

im not sure realy, thats what i need to know.

Slowboy Racing

Not quite sure from the above if you’re making or not making boost.

You don’t need the restrictor pill when running the AVCR, if the DV was leaking you would not make your desired boost target.

You mention you relocated the Solenoid? I would suggest you start by putting this back in the original location with the original pipe lengths as the problem seems to have stemmed from this.

pat

I'de be looking at the MAP sensor plumbing. It's easy to dislodge the pipe from the pressure sources switching solenoid. Just follow the pipework from the MAP sensor to the pressure sources switching solenoid, then out of the other side of that back to the inlet manifold.

scooby46

iTrader: (2)

My boost settings are
A - 1.5bar currently only reaching 1.4bar, sometimes 1.3 + 1.2bar
B - 1bar currently only reaching 0.8 bar

When the boost solenoid was in its original postion it was sat on its side. I was told that this wears the internal parts of the solenoid out quicker so thats why i moved it to an upright position. Ive chopped and changed the old pipework so theres no chance of it going back on.

I noticed that the car jolts on hard boost (with a flash of the engine light) in both setting 'A' and 'B' but doesnt when its switched off.

scooby46

iTrader: (2)

Im not sure if mine has a map sensor bud. Isnt it on the 96 impreza onwards?

pat

All turbo Imprezas have MAP sensors, the OE ECU uses its readings from the MAP sensor to control the boost pressure. It is found on the driver's side suspension turret next to the wastegate control solenoid. The vac line enters the BOTTOM of the sensor and loops round to the pressure sources switching solenoid, which has three ports; one for the MAP sensor, one that goes to the engine and one which looks like it has a dinky little silencer on it

scooby46

iTrader: (2)

ok ill have a look at that later and see if the hoses are ok.

scooby46

iTrader: (2)

hoses all seem fine. spoke to a mechanic today and he reckons its overboosting. How can i investigate this?

pat

That does not make sense. Previously the car was running 1.4 bar without hitting boost cut, yet now it won't go over 1 bar before hitting the cut. So, if the AVC-R is controlling the boost again, then it should be making 1.4 without cutting. Something else must be responsible for the fact that now it won't allow over a bar of boost without cutting!

Now an STI 2 (GC8C4ED) comes with a normal MAP sensor for that year that cannot read 1.4 bar. This means one or more of the following must be true :

• The sensor has been replaced by a later one
• The sensor has been replaced AND the ECU has been adjusted
• The sensor is original but the ECU has been adjusted or replaced
• The sensor is original but a bleed was introduced to stop cut

That's not an exhaustive list but you get the idea

In the first instance the ECU is being fooled into seeing lower boost than there really is, hence avoiding the cut.
In the second instance the ECU has been told about the new sensor and has also been told that 1.4 bar is OK.
For the third there are two possibilities... either the ECU is one of the rare ones that never flag a sensor fault; in over a hundred ECUs I've seen one or two, so unlikely but possible, but it wouldn't cut.... ever. The other option is that the ECU has been replaced and told to ignore the sensor (eg PowerFC without boost control turned on).
The final option is a bodge that can be used if you're confident that the map is fine; bleeding some of the pressure away from the sensor will raise the boost cut proportional to the amount bled. If there was previously a leak and you inadvertently repaired it, you may have reinstated a cut that was accidentally disabled prior to the move.

It would be useful to know what ECU is in the car etc... is it stock, has it been mapped etc ?

scooby46

iTrader: (2)

Im running an Apexi pfc ecu. The boost is controlled by the AVCR boost controller. It was mapped by JGM and he set everthing up. I remember seeing the standard map sensor still connected to the loom. Not sure if this is correct. The car was running fine untill i relocated boost solenoid and replaced the boost vac hoses. I may have inadvertenly plugged in something i shouldnt have. I.e the original map sensor.

pat

Normally when a PowerFC is fitted and you want to run over 1 bar of boost with the original sensor you just have to disable the boost control and also the boost cut in the ECU, you just trust the external boost controller to keep the boost at sensible levels. If you have the boost control kit option, that comes with a new solenoid and sensor that can read more boost, with it fitted you can run more boost AND still have the safety of a boost cut. It does sound like you don't have the kit though, so if the ECU is boost cutting then it suggests it is on the original sensor but the boost control wasn't turned off (possibly because it wasn't reading to start with anyway, hence no problem) but your best bet is to have a word with Simon, he'll have the map there and can tell you what causes are possible, and which ones aren't whereas I can only list every possible cause...

scooby46

iTrader: (2)

ok thanks for your help pat

blacrat00

Hi i got sti 96 v2
mine doing similiar, i set my boost to 1.6 psi,,,,, not sure what that is in BAR. but still upto 18psi to 6900 revs.

driving me mad or is 18psi ok
JJ