Re: Testing Knock Sensors

["Bernard Littau" <bernardl@acumenassociates.com>]

[lots of snip]

I've not seen this 0.7 bar limit in print.  Where/how did you find this out?

I thought, from the Bentley, that the MC knock sensor was ignored only below
1800 rpm.

1800 rpm makes more sense to me than a limit based on manifold presure, as
rpm measurement is direct and deterministic.  Manifold pressure is somewhat
more ephemeral.  The boost pressure sensors are not known for accuracy.

However, when my air temp sensor connection went open, and the ECU thought
it had hot hot hot air, the check engine light would consistently come on at
0.8 bar, which does tend to support some ECU state change when over 0.7 bar.
It clearly wasn't sensing the bad air temp sensor until 0.8 bar.

Does anyone know if the MAC ECU's in the MC series are based on a H8?

Best,

Bernard Littau
Woodinville, WA
'88 5kcstq