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Discussion Starter · #1 ·
Couple of (I hope) quick questions.
Does the 1997 900 turbo have a seperate knock sensor, or is integrated into the DI cassette (red)?
If it is seperate, where is it?
Will a bad knock sensor cause the turbo to stay at base boost? I can't find any leaks...
Thanks all
Bob
 

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Trionic 5, 7, and 8 use the spark plugs as knock sensors, so no, there is no separate knock sensor (like the piezoelectric microphone used on the C900). The DIC is part of this circuit.

If your turbo seems to be stuck at base boost, checking for leaks is the first thing to do, as you have indicated. This must be done thoroughly, as small cracks in the pressure piping will not always be visible when no pressure is present. It must include checking the hoses to the AIC, and the vac lines from the throttle body, as well as ensuring that your BPV is functioning properly. If you have plastic endtanks on your IC, ensure there are no breaches in the integrity of these. You must be certain that your wastegate is not stuck in the open position, and you must ensure that your BPC valve (boost pressure control valve) is operating correctly.

Also, make sure you have the correct NGK plugs gapped to just under 1mm, although this alone is not likely to cause the car to run at base boost only.

Are you getting any CEL codes?
 

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Discussion Starter · #3 ·
Thanks for getting to this so quickly.
No codes.
I plan to pull the hoses off this weekend (carefully) and get a detailed look for cracks etc.
Last night I found a bolt missing that attaches the throttle body down...I'm thinking that might be a leak source...heading to the salvage yard this weekend to find acouple of spare bolts...
 

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Discussion Starter · #4 ·
The wastegate seems to move nicely, and plugs are surely in need of a check-
what's the best way to test the BPC? I've seen a lot of different suggestions...
 

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There is an o-ring in there to keep that portion of the tract sealed. Could be you are losing your boost there, but does not seem like it could be enough to keep it at base boost only. Of course, the o-ring might be shot to snot now too, which could make the leak more substantial.
 
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