DaveC1

Got a prova ecu fitted on my sti V2, but only boosting at 12lbs, acording to my boost gauge. Took the top off today expecting to see that the J1 resistor had been soldered back in , but to my suprise it wasn't , in fact it had been removed alltogether, not just disconected. The extra board was in place , as it should, so why arn't I boosting much higher, should be about 16 lbs. Help me

Jolly Green Monster

iTrader: (4)

Are you are not muddling lbs and psi??

DaveC1

Yes mate 12psi. Any ideas wots going on

DaveC1

Does anybody Know what the rating is of the J1 resistor so I can put it back

dj219957

My understanding was that its resistance almost nothing. I.e that of a normal peice of wire.
I stand to be corrected.

XK-R

Nope you are right.

Do you have a full decat?

Becareful of the Prova ECU at the higher end of the rev range as it has some high advance for the Jap Fuel.

Eddie.

DaveC1

Thats what I'm thinking and why I want to replace the J1 to overide the eprom board. However it did confuse me why I am only getting 12psi. I've read some where about cleening a solonoid out. Where will I find that?

Jolly Green Monster

iTrader: (4)

agree that a bit of wire will work on J1.

XK-R

You mean boost solenoid?

Do you have a full decat as this can hinder boost.

Put a switch in where the resistor was and then you can quickly alternate between the 2 if needed.

Eddie.

DaveC1

I've got a Decated down pipe and a hks back box, none of which i've done. Very loud . sounds a bit crap. I'm sure the centre cat is still there, I was thinking of replacing the system with something like a mongoose which would mean I would be fully decated.

DaveC1

I must say with the amount of noise I was a bit concerened that I might have been lacking back pressure for the turbo. Still a bit confused as to why there was a bleed valve on with an eprom board. I know there used with piggy back chips. Correct me if i'm wrong

Delboy2

A decat in most circumstances will cause the boost to rise over the target due to the reduction in exhaust back pressure which will result in the turbo spooling quicker.
The Prova ECU has a 16.47psig boost target so with the decat it is possible that it is rising higher which could explain the addition of the bleed valve as the standard map sensor 'saturates' at 17.2psig even though the boost/fuel cut is set to 19.67psig which will initiate the cut much lower

Cheers

DaveC1

I see. So why only 12psi , should I be looking at my actuator or boost solenoid

Delboy2

From the above statement I am led to believe you already have a 'bleed' valve fitted??
If there is one fitted this over-rides the oem boost control solenoid so the boost will be governed by what the bleed valve is set to

Cheers

dj219957

Correct. The reason you have only 12psi is becuase a MBC has been fitted to cap the boost. As mentioned this was proabably fitted at the same time as the decat cos the decat could have caused overboosting over the already hign 16.2psi. If you want more boost then adjust the MBC.
Be carefull

Andy

DaveC1

where bouts in Staffs. are you Andy

Delboy2

As stated above if you increase the boost using the MBC be careful because although the Prova map is one of the safer of the JDM maps the ignition map is still rather advanced and is set for use with 100Ron fuel A knocklink would prolly be very beneficial

Cheers

DaveC1

I think i'm going to take the mcb off, bridge the J1 and hopfully I should be running as standard. I totally agree with the Knoklink idea and wouldn'mind a MAF metre. Want to got this fantastic car sorted properly

Scott.T

iTrader: (2)

Are you sure you have an STi V2 and not an STI RA.
The early RA ran higher duty cycles and hence the prova map that is being talked about would under achieve.

DaveC1

Funny you should say that because I havn't got ABS which would sugest what your saying, however all ra's that year where white with a roof vent, I'm silver and Havn't. Perhaps it's a mongral

DaveC1

Things have got much more confusing. I have removed the MBC and bridged J1. Max boost is now 6 psi and flicking the switch bridgeing J1 has no affect at all. Wonder if my boost gauge is accurate. Its a collins, on tickover it reads -10 . It reads in lbf/in2. Does this all sound right?

Scott.T

iTrader: (2)

You probably havn't got the standard boost control solenoid in the vacum circuit. 6psi is actuator cracking pressure, so the switch won't make a difference.

Uou should have a hose from the turbo outlet nipple going to the brass solenoid mounted on the drivers side strut top. A hose from this returns to the actuator.

The very bottom hose (of the 3) plumbs back into the larg black plastic expansion box on the air intake.