I am having problems with overboosting in 5th gear. I am running a Greddy ProfecB boost controller set at 1bar. The unit has 2 settings, low boost and high boost. Now through the gears in low boost, it holds it’s set boost even in 5th with no problems what so ever, however, when I put on high boost 1st-4th it holds it’s boost, but in 5th gear it overboosts to about 1.4bar. I’ve recently contacted GReddy , and this was their reply::::” If it works fine in the other gears, it is most likely an inherent problem with the engine size and wastegate sizing or exhaust back pressure.”
I’m also running a HKS induction kit with a Nur SpecR and d/p and a Blitz bov
Can anybody advise me on what steps to take, could it be that I might need a new wastegate??

Cheers.

CRAFT

 

Is there a gain setting you can turn down?

 

I had the same problem,get a wastegate,that should sort it out..

 

What Boost is it you're holding in "low boost" mode in 1st - 5th, what Boost are you holding in "high boost" mode in 1st - 4th?

What ECU do you have on what MY?

Matt

 

I would say if it's working in "Low Boost" mode at the same Boost as "High Boost" mode is not working then it's a problem with the Boost Controller......

Matt

 

agree

 

Set the low boost to 15psi and high boost to 12psi (if you can do that). If it creeps up over 12psi in 5th on the high boost run then its got to be the Boost Controller.

Justin

 

Justin, never thought of that I'll try this weekend.
BTW, what is 12psi & 15psi in bar?

Cheers peeps!!

CRAFT

 

0.828bar and 1.035bar

Matt

 

Optimax and downpipe will give quicker spool up necessitating different setup.

 

Cheers John, wasn't aware something as minor as petrol & d/p could affect it so much. Ya learn something new every day

CRAFT

 

Right then, it’s a 94 WRX, running a standard ecu. In low boost it’s set at 12psi(bar?) and in high boost it’s set at 15psi. I normally
leave it in low boost for week driving and change to high boost at the weekend. I now have it permanently set on low and have increased the low boost to 15psi(1bar?) with no problems in 5th in low boost!!
The controller ProfecB has a sharp or mild dial which is used to alter the wastegate boost response. I have tried this
but with no joy. I have had a local tuning company come out with me whilst going through the gears, and he thought it might be getting to much air. I had it set up last year and it ran no problems until recently. Back in february I had the d/p fitted and tbh I can’t remember if it started then or before, I’m pretty sure before.

CRAFT


[Edited by CRAFT - 3/5/2002 7:29:39 PM]

 

Right then, set it up today. Seems to be working fine, however, the controller seemed to be set way to high. I've now got it in high boost set up on 15psi, and it holds boost in 5th no problems at all, and also the settings on the **** are about 4 notches away from the original position So now the set up is-low boost 12psi, and high boost-15psi. What could have caused this, ant ideas? Could it be that I have fitted a downpipe and running optimax, as I haven't touched it since it was set up last year!!
Anyway, hopefully no probs from now on, and any answers to the Q's above would be grateful, just curious!!

CRAFT

[Edited by CRAFT - 3/9/2002 5:43:36 PM]