Custom PCM & Injectors Questions

[Bob Tom]

Hi, Grumpy.

At 08:32 AM 3/27/00 -0500, you wrote:
>Which PCM?.

The PCM is a '96 Mopar Performance hi-po computer.  My vehicle
is a '97 Dakota 318 with 19# stock injectors, MP camshaft,
and better breathing and exhaust modifications.

>Customized by who?.  For doing what?

This computer was custom programmed by a company in AZ by the
name of Z-Industries (I believe) for an owner of a Ram SS/T
360 with a Paxton SuperCharger and N2O.  The goal was to increase
performance for the 1/4-mi. track.  The first computer sent to him
with the custom program was erroneously put on a Dakota computer.
At the time, he was told it was for a '97 and, hence, my interest
and one of the main reasons for buying it.  (MP has never put out
a hi-po PCM for the '97s).  The '96 and '97 Dakotas are both OBD-II
compliant but went through a major exterior design as well as major
differences in how sensor outputs reach the dash gauges.

I do not have the technical specs of the custom program but
I was told that it was calibrated to run with 30# injectors,
calibrated for 160F coolant thermostat (stock is 195F with
most performance Daks running 180F tstat), all delays were
removed to give instantaneous throttle response, rpm and
speed limiters were raised, tranny shift rpm points were raised,
idle rpm raised, prevent detonation for 10lb supercharger boost
and 150hp N2O shot, etc.

While my surface knowledge of efi is enough to tell me that
running this PCM on my vehicle is a gamble, I took the chance
and am taking the time to put it through careful road tests with
a scanner. 

At idle, scanner outputs show that timing has been advanced more
than the MP hi-po PCM and pulse width of 19# injectors is shorter
than with the MP PCM (I'm looking to see if the scanner can
output duty cycle data).  In closed loop, the o2 sensor is doing
its job bouncing readout of rich and lean with longer stays at
rich.  At WOT (open loop) and initial startup, it shows rich.

As previously stated, under sudden WOT at any rpm, there is a
sustained 'bogging' with the 24# injectors, and hence the return
to the 19s.  Gradual changes in throttle position does not
cause this problem.

>> Generally, are there any effects on the life expectancy of
>> running the stock injectors with this PCM? 

>> Also, the computer has been programmed to remove all delays.
>> What are possible delays that can be removed?

My questions were more of a general nature since I do not have
any tech specs of the custom program.  It seemed to me that, if
a program is calibrated for 30# injectors, pulse width would be
different than a program calibrated for 19# (or 24#) injectors
as well as duty cycles (???)  I have complete zero knowledge on
delays.

I've tried accessing the archives to see if there is anything
in these subject areas (does not have to be specific vehicle
related) but have been unable to access them lately.

If there are any sites in which I can get a little deeper knowledge
into engine/fuel management, I would appreciate any references.

Thanks for taking the time to reply.

Bob
----------------------------------------------------------------------------
To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes)
in the body of a message (not the subject) to majordomo at lists.diy-efi.org