Re: '88 5000CD TQW engine knocking

[ptimmerm@mashtun.JPL.NASA.GOV]

>Intermittently, the digital boost guage will stop functioning and read
>0.0, or 0.1
>Once this happens, the engine will knock under hard acceleration
>(pinging begins at about 3800rpm).  No warning lights come on.
>When the boost guage is functioning properly everything is great!

Well, it's pretty clear that the pressure sensor, or it's associated
hardware have an intermittant failure going.  When you get zero out
of the pressure transducer, you get no boost retard out of the 
computer, and that gives you knocking.  So everything matches up.
We have some guys doing conversions to aftermarket pressure
transducers, because the stock ones fail when subjected to big
pressure spikes, as seen with big boost cars when going off throttle,
such as shifting.  you could also have something bad on the main board
in the ECU.  Doesn't sound like your in the US off A, more like the UK.
I suspect Phil can steer you right if your in that neighborhood.
If I am wrong, and you are local to the US, I am sure that one of
the Scotts (m or j) would be happy to help out.

paul timmerman