18
Dual Units:
Each gauge will have a separate part number, in the form of
PTX01 or PTX02. The ones that end in “1” will be fully functional, the other
will not have the performance timer function. This was necessary to eliminate
the possibility of overloading the data bus with too much traffic. If you run
either gauge at the #1 data rate (fastest), the other should not be run lower
(faster) than #3. Both can be set to #2 or higher (slower). Knowing this, set
the PRO gauge for parameters that require monitoring at a high data rate, such
as knock retard or ignition advance. This way you will catch any transient or
quickly changing values. Slower changing parameters such as intake air temp
or engine coolant temp can be logged on the Standard gauge at 2-3 times per
second without missing anything important.
SRT
-
4/PT Cruiser Dual Units
: This set will consist of a Pro version and a
Standard version gauge. The Pro will be fully functional, the standard will not
have the performance timer. These steps were necessary due to limitations of
the SRT-4 bus. It simply cannot handle the high rate of acquisition that two
gauges running full speed produce. If you run either gauge at the #1 data rate
(fastest), the other should not be run lower (faster) than #3. Both can be set to
#2 or higher (slower). Knowing this, set the PRO gauge for parameters that
require monitoring at a high data rate, such as knock retard or ignition
advance. This way you will catch any transient or quickly changing values.
Slower changing parameters such as intake air temp or engine coolant temp
can be logged on the Standard gauge at 2-3 times per second without missing
anything important.
SRT-4/PT Cruiser vehicles using MAP clamps
: The clamp will effect the
horsepower reading, skewing it low. The MAP sensor output is used in the
equation, and clamping it will result in an inaccurate value.
Analog inputs:
On some vehicles signal ground and chassis ground are at
different potentials. Depending on how the source of the analog signal is
grounded, a voltage offset can result. For example, in our
test vehicle, an ’03
Mustang Cobra, there was a 0.01v difference between the chassis ground
which we used for a 3 bar MAP sensor, and the signal ground on the OBD2
port which our Interceptor was connected to. This resulted in an offset of -0.6
psi after the conversion was entered. We saw this with the ignition on, engine
off, where we should have seen 0.0 psi but instead saw -0.6 psi. To correct
this, we adjusted the intercept value of the analog input by +0.6 to eliminate
this error. We have not seen this grounding issue on many cars, but if you see
it on yours this is how to correct for it.
