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Salutations:
Actually - the resistance isn't perfect, but not shorted out completely either. You are Trionic if you have an ignition cassette instead of spark plug wires and a rotor and there is one final set of tests before condemning BPC:
Get someone to turn on the ignition while you are listening to the BPC - but don't start the car. If the solenoid clicks, verify that it is actually using it's air passageways as outlined below.
If it doesn't click (and sometimes even if it does) - then the coils may be too far gone (despite correct resistance) or the control disk and/or vent ring is jammed and/or broken (hence the buzzing). Unplug your BPC from the wiring harness until you can have your APC computer tested to make sure it isn't (or isn't going to be) fried as well.
If you got a good click on power up - remove all the hoses from the BPC (mark them carefully) and light up the ignition again without turning on the motor.
Using a length of 1/4 hose - you should be able to blow through the top nipple on the solenoid (marked C) and feel the air come out the bottom nipple (marked R) - but very little air should pass to the middle nipple (marked W). With the solenoid closed (key off or solenoid unplugged), C to R air circuit should be mostly closed - but you should have air flowing freely between C and W (Wastegate).
If you are seeing something else against above tests - then is it likely that your BPC is in fact knackered (broken/jammed control disk - near dead solenoids) and will need to be replaced.
Check the routing of the hoses (it sometimes happens that they get messed up). Top to bottom - C goes to the nipple on the turbo's compressor, W goes to the wastegate actuator (the small drum on the side of the turbo with the rod and hose attached to it), R goes to the main air intake closest to the filter.
If everything check outs correctly - then you may have a bigger problem with the APC computer or the wastegate. The first problem will require a electrically savvy shop with the proper tools to check the loom and the computer. If the second problem - your wastegate actuator could be spent - so have it checked again too.
The BPC unit should fail deliberately to base boost when something goes wrong with either the electrical or air circuit (free air to W regardless of pressure) so that you don't blow up your engine.
If you are over-boosting - you really need to fix it soon so you don't destroy the engine, turbo or attached pressurized devices (safety valves, intake manifold seals, cruise control, BPV, intercooler, wastegate actuator, etc, etc.)
If the BPC is in fact the culprit, I will happily pay postage to my bench for the dead one when you decide to replace it. I am testing some repair ideas to destruction and need a small supply of broken BPC valves to work on before I write up the final details.
It may be that BPC units are repairable before they get too far gone, but I'm not sure the repairs I have in mind substantially decrease lifespan or interfere with proper air circuit balance once implemented.
Dexter J
posted by 24.222....
, Fri, 20 May 2005 04:59:10
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