Scott.T

iTrader: (2)

I have an intermitent lack of power only noticeable in 1st gear on fast launches.

I beleive it may be the Boost control solenoid occasionally sticking/failing.

So hence I am after the loan of a known working example to evaluate if it solves the problem.

I have tried cleaning it out with brake fluid, but the fault still persists.

The Boost gauge doesn't help either as the fault is so intermitent that by the time you look at the gauge when the prolem occurs you are back on full boost.

If it comes to it I may temporarily replace the solenoid with a bleed valve (carefully set).

AndyMc

Hi Scott

The boost control solenoid has no way of knowing what gear the car is in.If your problem is the boost solenoid I would have thought it would show up in the other gears too.

Andy

coyote

Scott,

Some Australian delivered cars (I think MY98 and 99 but not sure) would do this when the throttle was completely open in first gear. Basically the engine would produce no boost (wastegate wide open) for a split second and then boost would build normally. It seemed to happen when the car is rolling slowly with clutch fully out and then given the wellie, not so much when accelerator/clutch go in/out together. Supposedly it was meant to stop gearbox damage caused by overboosting as the turbo spun up? That was the story anyway. The only fix I've heard of for this "feature" is fitment of an aftermarket boost controller.

Scott.T

iTrader: (2)

I don't see how the wastegate can be momentarily open in 1st gear as it is a mechanical device that only opens when it reaches it's pressure limit.

It can only reach this limit if the wastegate is closed to enable the build of boost pressure.

I don't see how a Electronic Boost controller will effect this unless ?

coyote

Me neither. It never happened with my car but I know of at least 6 that reported the exact problem. A couple fitted aftermarket controllers and the problem was gone.

coyote

I'm going to take a stab in the dark here, never really thought about it before.

Let's assume for a second that the ecu senses a fully open throttle in first gear. It recognises this as a bad thing and tells the boost solenoid not to bleed any pressure so the wastegate sees actual manifold boost pressure. From memory most of the actuators have a spring that compress under about 7psi of pressure. 7psi of boost would seem like nothing if you were used to taking off with 14psi.

Pure speculation. As I said, I haven't experienced this myself although friends of mine have. I'll ask some questions for you and try to come up with some more informed info.