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APC solenoid Posted by Ari [Email] (#2847) [Profile/Gallery] (more from Ari) on Fri, 11 Apr 2003 08:58:53 In Reply to: Ticking noise '90 Saab Turbo; stops when brake pressed, Jay, Fri, 11 Apr 2003 07:32:36 Members do not see ads below this line. - Help Keep This Site Online - Signup |
That's the location of the APC solenoid, the one that controls turbo boost. When energized, it allows full boost; de-energized, you only get base boost.
The click you hear is the solenoid turning on and off.
The APC system is designed to go to base boost when you press the brake pedal. Makes sense - you shouldn't need full boost if you're trying to slow the car down. When you hit the pedal, the solenoid can't turn on, so the clicking stops.
The question would be why the solenoid is clicking at idle. I assume it's at idle, because there should be no way to hear it click at speed. Depending on the year and model (such info is always helpful), it may be normal. After all, you don't need any boost at idle.
As long as you're getting full boost (needle to end of yellow/beginning of red) when you ask for it, don't worry. If you arent' getting full boost, that's a different story.
posted by 192.249....
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