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Re: apc issue Posted by Ari [Email] ![]() ![]() In Reply to: apc issue, 9000man, Sat, 23 Jul 2005 12:20:18 Members do not see ads below this line. - Help Keep This Site Online - Signup |
A lot more information is needed.
For the BPC solenoid, the middle pin is tied to 12 volts. The two other pins go to the ECU. The ECU switches these pins to ground. The BPC is a valve with an adjustable position. The ECU pulses one side to ground to move the valve one way, and pulses it to ground to move the valve the other. These are pulses at about 800-1200 hz (cycles per second). Tying one side to ground will burn out the valve, so don't. A properly operating BPC will 'buzz' when the engine is running. If it isn't buzzing, it could be a bad BPC solenoid, or a bad ECU.
If you stick a voltmeter on either one of the outer legs when the engine is running, you should see a voltage greater than 0 and less than 12. That's because you're looking at a bunch of pulses. Since the meter can't read that fast, it will average them.
Let's start with a few basics-
What year and model car? It's got a three wire BPC, so that narrows it down a little. But more information always helps.
How many miles on the car, what kind of shape is it in, and has it always had a base boost problem, or is it a new problem? Did you just get the car with the problem?
You've checked for vacuum leaks. Let's start with the easy stuff - What octane are you running? Have you tried running the highest you can find (93 or 94 in the US) and see if that helps? How do the spark plugs look? Are they the right kind, gapped properly? Air and fuel filters fresh?
Is the knock sensor loose? How are the motor mounts? Shot motor mounts can cause the knock sensor to think the engine is knocking.
But let's start with the year and model.
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