Hi all,

I have a wierd problem on our Sti Wagon Ver3 96.

Between 3500RPM and 4500RPM on the move I get a strange whine which sounds like it's coming from the inlet track/air filter, in all gears mostly on part throttle/boost. If you build up boost at 3500RPM, floor it and run through the whine/rev range of 3500RPM to 4500RPM the power and torque is noticeable down. If you part throttle it through the above rev range, past the whine and then boost it say at 5000RPM the car is fine and as quick as normal. The boost is also fine and steady at 1.0 bar.

I'm going to check the inlet track for leaks on the weekend as this may be the problem but it seems strange that if you boost early on and drive through the whine the power is down, yet if you part throttle it through the whine and then boost it later in the rev range it's fine. It makes motorway journeys a pain as your always around that rev range in 5th so hard to drive through it!

Any suggestions appreciated.

Thanks

 

Going to remove filter and test drive shortly, it's a mushroom HKS one. Will see if the noise changes at all without a filter

T

 

Right ran without the filter and it made no difference, the noise is still there so it's not that. It's a strange one, at certain times when you put your foot down the power is just very flat, like there is less torque or you were loosing boost but the boost is still holding fine. Other times when you floor it from a standing start and go through all the gears it's really quick and feels fine again.

It only seems to be if you part throttle it, build a little boost, then floor it then the flat power comes into play. It's all related to this whine I hear around 4000RPM - 5000RPM. When boosting below say 4000RPM and continuing to the top of the rev range it's really flat (almost as if it's struggling), when boosting from say 5500RPM and up it's totally fine it's only when you boost lower down the rev range that it gets stuck in slow mode besy I can describe really!

Any help appreciated or if anyone has experienced any similar issues that would be grand otherwise will need to investiage on a dyno to find the issue. Could the 98RON UK fuel be effecting anything like this as it's a fresh import.

Thanks