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Posted by IrieTom [Email] (#1032) [Profile/Gallery] (more from IrieTom) on Fri, 28 Sep 2001 01:08:44 Share Post by Email
In Reply to: Hiss noise from dash when boosting.... normal????, Dylan, Thu, 27 Sep 2001 22:26:50
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I experienced the same thing- the rubber diaphragm inside the overboost cutoff switch has worn out and cracked. Find the vacuum hose connected to the back of your turbo boost gauge in the instrument panel and follow it back to the overboost cutoff switch. It's under the dashboard, right behind a few relays above your shins. The device has two vacuum hoses and two wires connected to it. This is your culprit.

The good news: Your performance is not limited by this. Actually, the OverBoost switch, when functioning, deliberately limits performance by cutting off the fuel delivery when the intake pressure (turbo boost) reaches a certain point. When the fuel cuts off, it feels like somebody switched off the ignition right in the middle of a heavy acceleration run. Whaaaaaaaa-ooh!! The seat belt grabs you before you hit the steering wheel.

The bad news: You risk blowing up your motor IF the turbo somehow starts boosting uncontrollably. The chances of this are low, but the O-B switch is there for a reason. Personally, I've replaced and tweaked mine so it cuts the fuel at a higher pressure than the factory settings.

Find yours, and replace it... Eventually.

Don't worry about killing your motor unless you use maximum turbo boost everywhere you go. Just make sure your turbo gauge doesn't hit the pin. This can be achieved by reducing the pressure on your gas pedal when the needle starts sweeping across the red portion of the gauge.



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