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If you want to get picky- Posted by Ari [Email] ![]() ![]() In Reply to: When is an APC a BPC ?, mark, Wed, 8 Sep 2004 20:11:21 Members do not see ads below this line. - Help Keep This Site Online - Signup |
In the early years of the turbo, The Automatic Performance Controller (APC) used a solenoid mounted on the radiator as part of boost control. Remember the old 900 with "APC" on the back? That was a solenoid, and it was an On-Off affair. Energized was full boost, de-energized was base boost. No real in-between. Two wires. Officially called "Solenoid Valve" in the EPC
In the '89-90 time frame, when the switch was made to Direct Ignition (DI), the device was changed to what the EPC calls "Boost Pressure Control valve." This is a three-wire device that uses high frequency pulses to adjust the valve position. So the system can select the range of boost pressures between Base and Full.
OK, so what? Technically, the BPC is the 3-wire device, the APC solenoid the 2-wire. However, they do the exact same thing, just in slightly different ways. And people use them interchangeably. Since the object of a name is good communications, APC or BPC, folks will know what you're talking about, and you'll understand them. And that's the whole idea.
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