Rob Muller

I have a 1993 Scoupe turbo. The wastegate solenoid is either broken or
the hoses are connected incorrectly. When the solenoid is not
energized, the air that comes from the turbo is routed to the
wastegate resulting in low turbo pressure.

This is how the solenoid looks like:
http://members.home.nl/rob.muller/solenoid.jpg

Hose number 1 is connected to the air intake, hose number 2 to the
pressure side of the turbo and number 3 is connected to the wastegate.
Is this correct?
The solenoid seems to work fine, that is why I suspect that the hoses
are not correctly connected.
It seems far more logical if hose 1 is connected to the turbo, hose 2
to the wastegate and hose 3 to the air intake. In this situation when
the solenoid is not energized any pressure in the hose to the
wastegate actuator will bleed off to the air intake. When energized,
the air pressure from the turbo is routed to the wastegate. Is this
how it should be connected?

Maybe someone with a Scoupe turbo can have a look to see how the hoses
are connected? The solenoid is located under the battery. You can see
how the hoses are connected without removing any parts from your car.

The online service manual (thanks Hyundai, this has been really
helpful several times) is not correctly describing my car in this
particular area. In the manual, the solenoid is not connected to the
pressure side of the turbo but to the manifold. This might be
explained by model differences between the cars from the US and the
Netherlands.
http://www.hmaservice.com/webtech/iindex.asp?id=7717

Thanks in advance.

Rob

Rob Muller

On Mon, 21 Mar 2005 04:11:31 +0100, Rob Muller <rob.muller@gmx.net>
wrote:

>This is how the solenoid looks like:
>http://members.home.nl/rob.muller/solenoid.jpg
....
>It seems far more logical if hose 1 is connected to the turbo, hose 2
>to the wastegate and hose 3 to the air intake. In this situation when

I have tried connecting the hoses to the wastegate solenoid in this
way. There is no obvious overboost, the last boost led does not light
up, and there is a lot more boost. It is a different car when rpm is
above 2500.
So there is reason to belief the hoses are connected correctly now.

There is one problem: at half throttle there is more boost and power
than at wide open throttle. What can cause this?
Can this be the ECM operating the wastegate solenoid to prevent
overboosting. I would expect the boost to stay the same instead of
decreasing if this would be the case though. Does the ECM measure the
manifold pressure in order to decide to operate the wastegate or is
this open loop?
Maybe the ECM detects knocking and operates the wastegate?

Sometimes the check engine light turns on: boost too low. Maybe the
pressure is not released fast enough from the wastegate actuator hose
when the ECM pulses the wastegate solenoid?

This car has been driven real slow for 5 years, I am not sure if this
has anything to do with the problem but it might be worth to mention.
The wastegate is not stuck. The engine does not stutter or jerk at
wide open throttle.

Rob