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Date: Thu, 22 Aug 2002 07:54:05 -0400
From: KeithG <noonenopsamspring.com>
Subject: Re: My dealer hasn't got a clue, can you help? ('97 9000 Aero, Manual)
the pressure transducer or MAP sensor. It is on the RHS firewall. It is
a small rectangular piece bolted to the false bulkhead and has a small
silicone tube connecting it to the intake manifold. As I understand it,
the BPCV on these cars is a dual acting solenoid valve. It probably
fails mostly in a mechanical mode and does not seal in one direction or
the other. Electrically, it would be pretty much work or not work. and I
would think it would show some sort of odd behavior at acceleration less
than WOT as well (wavering boost, lagging accel, delayed boost, etc.) I
am just musing here, keep that in mind. I have the trionic engine
control manual for a 96-98 NG900 which is similar but not exactly like
the 9k. I do not think that this manual is much more than U$20.00 and is
available from the dealer. Basic system operation is all controlled by
the ECU (spark timing, boost, fuel injection). It does not have an Air
mass meter, but uses a Manifold Absolute Pressure transducer, air temp
sensor, throttle position and a lot of math to determine fuel delivery
and boost limitation. You say that the the ECU and BPCV have been
replaced... The wiring is 3 simple wires from the ECU to the BPCV. I
think it is also 3 wires to the MAP sensor as well. You could always pin
them out to check for continuity and ground. good luck and keep us posted.
KeithG
Lee Marshall wrote:
> The problem is not intermittent, it always happens when the engine is under
> load i.e. full throttle in 3rd, 4th and 5th, pulling from low revs, it
> happens more if the car is carrying extra weight. Thankfully I never have to
> tow anything. It is not affected by heat, road conditions or anything.
>
> I've never heard of the pressure transducer, where is it situated? It could
> have already been replaced, so much has! BTW all the hoses have been checked
> or replaced.
>
> My personal thought is that it is some kind of electronic connection
> (probably to the BPCV) that can only be tested when the car is at full
> boost, making it almost impossible to test in the workshop.
>
> Does anyone know where I could get hold of a wiring diagram for the turbo
> system?
>
>
> "KeithG" <noonenopsamspring.com> wrote in message
> news:3D63F9D3.6000903nopsamspring.com...
>
>>Lee,
>>
>>They replaced the part I would suspect 3 times. It shows you how much I
>>know... I think I would have to get to know Trionic a bit more to hazard
>>another guess. I would disagree, though, with some of the previous logic
>>used, but what do I know. Have they looked at the pressure transducer
>>its hose, fitting or its wiring? Is it possible that the pressure
>>transducer hose could be a problem or the transducer itself? From my
>>limited understanding, I would guess that the system, somehow, does not
>>know that the pressure has exceeded normal values. I could imagine a
>>pressure transducer which is nonlinear and reports decent values back at
>>idle and vacuum and becomes nonlinear and under reports pressure at
>>higher pressures. A wastegate would stand an outside chance of causing
>>this, a BPCV could do this, too. If the system is operating properly
>>(still an IF, but mostly confirmed) and still overboosts, it HAS to be
>>that the pressure signal is not reported correctly to the system. Does
>>it do this all the time? Does it do it cold and hot? Over bumps and
>>smooth pavement?
>>
>>Just some ideas YMMV!
>>
>>KeithG
>>
>
>
>
>
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