Date: Fri, 15 May 1998 12:52:10 -0700
From: Justin VanAbrahams <jvanabranopsamnet>
Subject: Re: Looking for info on APC

Jake Russell wrote: > > It's a volkswagen with a 1.6l turbo-diesel engine. You can read all about > it on: > - VW Golf GTD: Brutal... but stuff you might learn could be useful to me. I am thinking about adapting the APC to a Merkur XR4Ti... ;) > I've found some good info from previous posts and searches on the web. Can > anyone verify or add? Apparently, the APC system was started on the '83 > 900, they made some changes in '86; or at least the brain was moved from > under rear seat to engine compartment. The components are: "black box" > (brain), wastegate solenoid + air hose plumbing, a couple sensors (intake > manifold pressure sensor and knock sensor are my guesses; are these right?) The system itself did not change until 1993 or later, when it was integrated with the fuel injection system to create Saab's engine management system, "Trionic." The system does consist of the brain, the APC solenoid, knock sensor, rpm sensor, a pressure transducer (turns vacuum/pressure signal into electrical) - and all the wires & hoses needed to hook this stuff up. This includes vacuum tubing to the post-turbo intake plumbing, the wastegate, and a pressure signal right off the turbo. Relocating the APC box (the "brain") from under the rear seat to the engine compartment also included some changes to the guts of the box, but not how it works. I would strongly recommend using the later (post 1986) system, since they are more common, likely more reliable, and there is more info on them "out there." > Does anybody know if the unit will function without a knock sensor? (I've > got a diesel which either is not prone to detonation, or thrives off > detonation, depending who you ask ;-) so anyway, I probably would try to > get it working without the knock sensor. It *should* go into failure mode without contact from the knock sensor. Since the *main* focus of the APC system is to monitor knock, I am pretty sure without a signal from the knock sensor the APC would think something serious had failed, and drop into "limp home" or "basic boost" mode. What you *might* be able to do is fake a knock sensor signal from somewhere or something else out. I am sure I have the testing proceedure for the knock sensor at home, so I could probably tell you what the knock sensor is normally reporting... > I suppose if I could find a used donor car that would be ideal; I could > just start examining the system and getting the parts I need. I'm in the > Seattle, WA area, so anyone have any leads send them my way please. No leads, but there is a site on the net detailing how a guy installed the APC system in his Volvo Turbo (not diesel). All the info you need should be there... > BTW, do the APC solenoids have a lifetime? No prescribed lifetime, but they do die. My '88 900T lost its solenoid at about 130,000, and my '90 SPG lost its at 44,000! They die - but not with any frequency or regularity. -Justin

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