ping

[Ross Myers]

>>I had an interesting time working on a friends Turbo Grand Prix.  It came
to
>>me with a rough idle so, slapped on the Diacom and found a consistent line
>>of 7 degrees knock retard all the time, cool, a new one on me (just wait).
>>No engine noises and all things are fairly new on this car (I put in a
while
>>ago; new injectors, some sensors and such), so I swap out the ECM with a
>>known good one (that is easier than swapping the knock sensor) and still 7
>>degrees all the time.  Swap out the knock sensor and still.  Pull out the
>>(single) knock wire from both connector ends and ohm it out, good wire and
>>not going to ground, even when shaking the engine by hand.  Check volts
out
>>of ECM, fine here.  Pull out wire and visually inspect its entire length,
>>good again, check wire loom and no pinch or running near anything that
could
>>cause a false ?  Tired of this stuff I just grab some twisted
pair/shielded
>>cable and run a new wire in a new wire loom and in a different location
and
>>presto, 7 degree knock gone and been so for 8 months (also tested it still
>>work by the usual thump test, and some higher boost, as we tuned up his
chip
>>for 100 octane).  I also took the braided shield of this wire and on one
end
>>(did not want to create a ground loop) secured it to a good ground, with
>>other ground wires.
>>
>>(always up to a new challenge)
>>Jeff Middaugh
>>tystorm at email.msn.com


GM Australia has a service Bulletin out on the Holden Calibra (Made by
Vauxhall), they for some reason didn't shield the knock wire on the Aussie
cars (The Euro ones are!!), anyway, with a new shielded wire a drill and
much loss of skin and 7 hours later you can fix the problem of 'intermittent
performance loss'. Geez my ol' T/A's knock wire has splices, no shielding
and running over things it shouldn't, Diacom rarely blinks an eye at
knock... Makes me wonder.

Ross Myers