Duramax LB7/LLY DSP5 User Guide
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Important DSP
5
Parameters and Tables
A0141
– DSP
5
Tune Switch Delay
This parameter is used to co
ntrol the ‘delay’ before switching to another tune will
occur once the switch has been changed from its current position. The timer can be
set to delay the switching up to approximately 7 seconds.
As an example, if the delay was set to 2 seconds and the switch was set to DSP
Program #2, the switch would need to be moved off Position #2 to any other position
for 2 seconds before the ECM will switch to the new position as set by the switch.
This could be used to automatically switch to a different tune when racing. You could
set it up with a delay of 5 seconds, so soon after you leave the line you turn the DSP
switch to another tune (maybe better suited to the top end of the track) and 5
seconds later the ECM will switch to this tune.
A0136 to A0139
– DSP
5
Staging Control
DSP
5
staging control can be used to limit fuel delivery amounts which in turn
allows you to control (or limit) power under certain conditions. The fuel limiting
table is activated by vehicle speed, throttle position and boost levels.
When table A0139 is active it will limit the fuel delivery amounts referenced to
RPM, this allows you to slowly and smoothly ramp out fuel as the engine RPM
approaches a value you might want to limit the engine to.
This function is useful for drag race staging by allowing you to launch at consistent
RPM or boost levels without trying to control the throttle manually.
The fuel limiting table will be bypassed once any of the parameters specified by
A0136, A0137 & A0138 are exceeded. Some examples below
–
A0136
(Vehicle Speed Limit) = 2MPH
A0137
(Throttle Limit) = 60%
A0138
(Boost Limit) = 18psi
With the above values, if the vehicle speed goes above 2MPH OR the Throttle
goes above 60% AND the boost levels stay below 28psi then there will be no
limiting.
If any one of the 3 parameters goes outside the limits specified then the limiting
table will be ignored. In the real world this set up (with the A0139 table set with
some low mm3 numbers) would allow you to limit boost to 18psi until the throttle
went above 60% or the vehicle speed went above 2MPH, both of which will occur
once the light turns green!
A0140
– DSP
5
Valet Mode
DSP
5
valet mode forces the ECM into a form of ‘limp mode’ which could be used
as a valet mode / reduced engine power mode. This parameter must be set to
enable to allow this to function.
Once it is enabled in the tun file, the ECM will monitor the state of an external input
to determine if valet mode is to be initiated. It is highly recommended that the valet
switch is not easily accessible so it cannot be accidentally engaged.
The wiring for this switch can be found on previous pages of this document.
