scan tools and WOT

[Roger Heflin]

On Wed, 14 Oct 1998, David A. Cooley wrote:

> At 08:25 AM 10/14/98 -0500, you wrote:
> >
> >I made an interesting observation while at the track this past Saturday.
> >I made 4-5 runs with Diacom recording data.  Then I made 5-6 runs with
> >the Diacom disconnected.  Guess what?  I was both quicker and faster
> >by .1-.15sec and 1mph with the Diacom disconnected....
> >
> >Wonder why????  This is on any '87 TPI/MAF motor.  Is the ECM that slow
> >that it can't optimally control the motor at WOT while transmitting
> >data?
> 
> Diacom is probably putting the car into 10K ALDL mode.  This fixes timing,
> raises idle etc so the tunings are no longer optimal.  Timimg is no ;onger
> varied by the chip according to the tables *or* knock sensor.
> Might check with Rinda Technologies and see if they have a way to allow the
> ECM to be in normal mode while Diacom is linked.
> Later,
> Dave

Diacom has options to allow normal mode they software just defaults to
ALDL mode, so if you don't know to change it, or forget to change it,
it stays in that mode.  I don't understand why it does not leave
things in normal mode, since for what most of us use it for that is
the mode we want.

				Roger