DDS DIRECT –SMT8Y DIY TUNING MANUAL www.perfectpower.com 2016/03/03
1. INTRODUCTION
Congratulations on the purchase of the SMT8Y. This piggyback unit is the result of 20
years experience in the automotive industry and is the latest design in the range of
SMT8 piggybacks.
It is similar to the Perfect Power SMT8T in size, but packs more features. In one
aspect the SMT8Y deviates from all other piggybacks: It has been designed and is
destined for the DIY market. My definition of DIY is: A person who is enthusiastic
about and understands engines and is able to work on his own engine for the
purpose of improving the vehicles performance.
The SMT8Y is a tool that can be installed to achieve that performance. This manual
will explain in a structured fashion each connection, the use and purpose of outputs,
and in general everything associated with the SMT8Y. Once the unit is installed you
will need the Let Ripp V2 software, and the DDS DIRECT SOFTWARE USER GUIDE as
well as a PC or laptop and a communication cable to get started. This manual can
also be used for training professionals because the terminology is common to all
Perfect Power LETRIPP products.
If you are an experienced engine mechanic, then you will find some of the
terminology strange, and you don’t have to read all sections.
2. HOW DOES IT WORK?
The SMT8Y ‘modifies’ engine signals. The signals are used by the ECU to ‘drive’ your
engine in a pre-determined fashion. By modifying the signals, we can change the
ECU’s response.
Example #1:
We all know that an engine runs richer when cold. So, if you want to run the engine
richer, you modify the temperature wire so that the ECU thinks that the engine is
cold. Then the ECU will enrich the fuel mixture.
Example #2:
Your engine has a Lambda loop. This means it controls the fuel mixture by a probe in
the exhaust. By modifying the probe output you can now ‘direct’ the ECU to change
the mixture to lean or rich.
Example #3:
The ignition point is derived from a crank sensor. By ‘delaying’ this signal you can
retard the ignition.
Note: The SMT8Y can also advance, but we will not go into detail here.
In most cases the ‘modification’ involves the cutting of a wire (the signal wire) and
routing the engine side (source) to an SMT8Y input. Then the signal is modified
inside the SMT8Y and presented as an output, which is then connected to ECU side of
the cut wire.
