Setting Rev limit

[88GtHatchback]

Im having a hard time understanding how the rev limiting works. I have an 8LD computer running the A9S strategy. Im sure I could find the answer on the tweecer forums but there down and couldnt find anything here. Here are the values that were stock:
Rev-Limit Half Fuel - OFF = 7500 RPM
Rev-Limit Half Fuel - ON = 8000RPM
Rev-Limit Maximum RPM[No Fuel] = 7000RPM
PIP Filter = 961
Can some one explain how these settings gets a limit of 6250RPM? Is there some formula for calculating the limit using the PIP Filter? What is the PIP Filter? I would like to set the limit around 6800RPM. How do I find the values to do this?

Thanks,
Clay

[Dale McPeters]

Here is one way to do it, there are others....

From EEC-Tuner Tuning Notes>

PIP
Think of this as a rev limiter using the following formula:
PIP = 6006250/maxRPM
maxRPM = 6006250/PIP
for example stock A9L
PIP = 961 maxRPM = 6006250/961
= 6250 rpms
Lower numbers give a higher rev limit.

The PIP is a sample rate frequency that limits the PCM program operating loop to a minimum rate. If the loop is sampled less then PIP times within one operating cycle (2 crankshaft revolutions), the PCM limits rpm.

With this logic, you should be able to set the pip to 1 and the car should run normally, but not limit RPM. I have tested this on an A9L processor.

[gt90stang]

88GtHatchback,

The PIP rev limiter is a pretty harsh rev limiter, kinda sounds like you've blown the motor....hate it. I prefer the half fuel on/off scalars instead. I set these both to the same RPM and the motor just stops pulling will not bad sounds. What happens is the PCM only fires every other injector giving half fuel.

Good Luck, Don

[93Cobra#2771]

Exactly, Don. Most set the PIP to max, and use the fuel limits for rev limiting. BTW, it the fuel limiters don't lean the motor out. They cut ALL the fuel to every other cylinder, thus making it a dead cylinder...

[Dale McPeters]

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