Date: Tue, 14 May 2002 08:52:59 +0100
From: "Andrew Hookins" <>
Subject: Re: My dealer hasn't got a clue, can you help? ('97 9000 Aero, Manual)

Lee, The APC solenoid is mounted on the radiator/fan cowling on the right hand side (looking from the front of the car to the back). It has three rubber/silicone hoses and an electrical connector. This page from Townsends Imports gives the location: Your looking for part number 179 (BPC valve) My OEM pipes are stamped with the letters C, R and W to aid identification: (C)harge, from turbo output, (R)eturn, to turbo input and (W)astegate. I suppose a blocked charge hose could also give you this problem. Inspect each hose and check that they are all in good condition, remember that the charge and wastegate hoses see boost pressure and so my have a leak that only opens up under pressure. I think that removeing the electrical connector from the solenoid keeps the charge - wastegate path permanently open, BUT CHECK THIS WITH SAAB FIRST. Doing this will allow you to run the car at base boost only (about 6 psi I think). This will rule out all mechanical and leaky/blocked hose problems. If you still get overboost problems then you could try fitting a hose from the charge side of the turbo directly to the wastegate as in this picture: Again, this should give you base boost only. NOTE: You will have to bung the return path. If this fixes it then the problem could be with the APC solenoid, the TRIONIC ECU or possibly the wiring harness. Hope this helps. AndyH "Lee Marshall" <> wrote in message > On Mon, 13 May 2002 08:27:34 +0100, "Andrew Hookins" > <> wrote: > > >Lee, > > > >Yes I was more or less repeating meme meme... > > > >Is the over-boost protection fuel cut-off mechanism active > >when the over-boosting occurs? If you're not getting fuel > >cut-off then this would suggest MAP sensor to me. > > I am only getting what feels like fuel cut off (it feels like you have > just hit a brick wall) once the boost has gone past the end of the > gauge. > > > >If there is a leak in the hose to the MAP sensor that only > >opens under high boost then most of the time fuel metering > >will be correct, but would tend to lean out in this over-boost > >condition (BAD). If the MAP sensor is faulty who knows > >what is happening to the fuel metering. The MAP sensor > >_could_ be just be reporting a reduced pressure or may > >simply stick at some arbitrary level and not report higher > >pressures. In any event, I think that a problem here would > >allow over boost conditions without fuel cut-off. > > > >If there is a leak between the APC solenoid and wastegate > >actuator then fuel metering won't be affected. If the problem > >is here then you would get over-boost rapidly followed by > >very obvious fuel cut-off. > > That would be it then. Where in the engine bay would I find the pipe > between the APC Solenoid and the wastegate actuator? I presume one end > would be on the turbo? Where is the APC Solenoid? > > > >AndyH > > > > Thanks for your in-depth help!

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