LETRIPP II XMS4A DIY MANUAL V2.1 www.perfectpower.com 40
PERFECT POWER XMS4A – Engine Management System DIY MANUAL V2.1
24.2 IGNITION ADJUSTMENT VIA SOFTWARE
You must set the ignition to be at 10 degrees at idle. So in the ignition map (F2) where the car
is idling set the tuning cells to 10. Check with the timing light what the ignition is on now. If
the ignition is at 10 degrees, well done, you can go to the next section. If it is not then you
need to adjust the ignition reference (ShiftF1). For adjusting retarded timing make the ignition
reference less. E.g.: go from 60 to a 55. For adjusting advanced timing make the ignition
reference higher. To get the correct ignition timing curve consult your engine manufacturer or
have a professional tuner set it up for you. Incorrect ignition timing can damage your
engine!
Note: The ignition reference must always be higher than the ignition point. The ignition
outputs are turned OFF if you have a reference of 30 and an ignition point of 31!
25. TIME TO START THE ENGINE
You are going to adjust timing, and fuel. You will load different maps into your XMS4A. If you
are unable to get the engine started go to section 28. Once the engine is running there are
some things that will need to be done, so let’s get to it! Having the following items displayed
in the LetRipp software will help a lot.
• RPM
• AMP
• Injector m/s
25.1 FIRST THINGS TO DO WHEN CRANKING THE ENGINE
Under first time cranking you must check that you have rpm. Normally it is between 180 and
220 rpm. The amp reading should be between 0.85 and 1.0 bar with the ignition on. Under
cranking the amp reading should drop slightly and with the engine running it will drop down to
the lower multipliers. Check the injector m/s time under cranking to be between 5-6 m/s.
There are three ways the engine will startup.
Good/acceptable.
The engine idles between 800 – 1000 RPM and it sounds smooth.
Revs too high.
Adjust the throttle stop or set the ETC so the engine idles at an acceptable RPM.
It almost wants to start.
Increase the fuel range.
When the engine starts you will need to stabilize the RPM if it is erratic. Adjust the throttle
stop (if it has one) to bring the rpm to 800. Get the fuel injection milli seconds (ms) between 2
to 3 m/s. Adjust the fuel range or the amp gradient to get the injector m/s right.
25.2
FIRST THINGS TO DISABLE WHEN THE MOTOR IS RUNNING
Disable the fuel engine temp and fuel air temp tables for now. We will use them later in the
manual. Disable the ignition map’s amp, engine and air tables. Disable the “AMP Extra. En” in
the system def.
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