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How the APC solenoid affects boost
Posted by BillJ (more from BillJ) on Fri, 17 May 2002 06:35:43
In Reply to: Boost problems.....(long), Harry, Fri, 17 May 2002 05:04:06
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As you probably know, in a conventional turbocharger installation, the wastegate actuator is connected to the inlet manifold so that the wastegate opens as manifold pressure rises, eventually reaching equilibrium at the maximum boost level. With the APC solenoid fitted, but not powered, this is the arrangement you have - the unpowered solenoid connects the wastegate to manifold, and does nothing else. In this condition, you have base boost.
When powered, the APC system uses the solenoid to increase boost beyond base by bleeding pressure off the wastegate actuator so it "thinks" the boost is lower and allows more boost. It is the electrically controlled equivalent of a "bleed valve", often used to increase boost manually.
So the APC solenoid is designed to increase boost from base, and the default condition if unpowered is base boost - unless the APC valve is leaking pressure to atmosphere, of course, in which case you will get higher than expected boost when unpowered.
Another suggestion (this might have been asked already): do you have cruise control and if so, does it work? There are switches on the clutch and brake pedals that shut off the cruise control while the pedal is pressed. These also reduce boost to base if they are activated. A faulty switch can cause permanent base boost.
posted by 161.71.171...
Posts in this Thread:
- Boost problems.....(long), Harry, Fri, 17 May 2002 05:04:06
- Darned "enter" key!, BillJ, Fri, 17 May 2002 17:20:02
- Re: Boost problems.....(long), BillJ, Fri, 17 May 2002 17:18:52
- Another Update...., Harry, Fri, 17 May 2002 11:19:07
- Re: Boost problems, Bob Davis, Fri, 17 May 2002 09:52:16
- First things first..., Eric Law, Fri, 17 May 2002 08:15:52
- Update, Harry, Fri, 17 May 2002 08:02:23
- Is it possible..., BillJ, Fri, 17 May 2002 06:57:13
- How the APC solenoid affects boost, BillJ, Fri, 17 May 2002 06:35:43 <-- Viewing This Message
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