LS9 Map sensor hack on a 2.5 bar OS.

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09-12-2014
IDRIVEAG8GT

LS9 Map sensor hack on a 2.5 bar OS.

Not sure if you guys will find use for this or not, but I've been doing some testing on an E38 with a 2.5 bar OS. I asked support if they were able to build a 3 bar OS for my application, and it unfortunately won't happen.

Anyways, the issue I was having is that as soon as I'd push the OS beyond 24 pounds of boost (pegging 255 kPa) the ECM would get all pissed off and shut the throttle, kill the fuel, and the timing, then light everything back off like nothing ever happened. So finally I decided that I needed a way to limit what the ECM can see. In which case just by one kPa,

I played around with it for awhile and found a new calibration you can use to run an LS9 sensor and limit it at 254 kPa. This cured my issue, and even if I turn up the boost to 28 psi the ECM stops at 254 kPa, in which case my boost referenced fuel system takes care of additional fueling.

Linear: 254.00 kPa
Offset: 7.60 kPa

This is the new cal.

I figure that now if anyone wants to run an LS9 MAP sensor on an E67 ECM, they can now do it with this calibration.
09-12-2014
DSteck

All that does is basically rescale the sensor readings.

If you disable the high voltage test for the MAP sensor, it won't freak out with the correct data.
09-12-2014
IDRIVEAG8GT

I have absolutely no idea what this one's issue was, but it obviously wasn't happy at all about it even with the volt test disabled. It set the code for it one time and I turned it off, but it didn't do anything. This is the only way that works so far.
09-12-2014
DSteck

Did you disable the actual test or the DTC?
09-12-2014
IDRIVEAG8GT

I disabled the actual high voltage test.

You're talking about the flip switch located in the MAP Calibration section correct?
09-13-2014
PST

Hmmm, I recently saw this in a 10 Vette file cal'd by lingenfelter. They rescaled the piss out of the map making it report a fraction of actual kpa. I put it back to normal, and even with big boost pressures, no issue at all.
09-13-2014
MikeOD

Do you have the boost fuel cut set to enable? The highest KPA value you can put in there is 256, and it defaults to 255 when you apply the OS.
09-30-2014
IDRIVEAG8GT

Quote:

Originally Posted by PST

Hmmm, I recently saw this in a 10 Vette file cal'd by lingenfelter. They rescaled the piss out of the map making it report a fraction of actual kpa. I put it back to normal, and even with big boost pressures, no issue at all.

Well when I rescaled this I took into account the offset, which makes the sensor report the correct kPA. Not sure why Lingenfelter hacked it up like that.

Quote:

Originally Posted by MikeOD

Do you have the boost fuel cut set to enable? The highest KPA value you can put in there is 256, and it defaults to 255 when you apply the OS.

Yes I set it to disable at 256 kPa. I went through every possible scenario of what could be making it do that. Something in the OS just doesn't care for the MAP to be be pegged. Maybe it was trying to roll back over into the lowest kPa column in the tune?
I never thought to check for that. In all honesty though it works well so far, and I was more happy to see that this calibration takes a positive offset so E67 guys can play nicely with this sensor.