Hey, I thought the internal map sensor on a LT8S only read to 20 psi. I just read the product spec sheet on their website and it says "max readable boost with standard map sensor - 25 psi"

My LT8S is about 5 years old, has their been an upgrade to the internal map sensor? Or has it always been 25 psi max?

 

To my knowledge, it has always been 20psi. Im sure the extra 5 is for boost creep?

 

map sensor can read 25psi.
BUT tuning points only go to 20psi.

 

plus what ever a map sensor says it reads at ie... like a 3 bar map is only good for 2 bar of boost due to 1 bar being accounted for vaccum to atmosphere pressure

 

The above is correct.

Microtech have a 2.5 bar map sensor in all units unless requested otherwise.

the 3 bar has tuning points up to 28psi

4 bar up to 45psi.

 

Ok cool, I was just wondering what would happen if I cranked it up past 20 psi. I wasnt planning on going to 25, just didnt want the ECU to cut the fuel or spark at 20.

Is that what would happen? A fuel or ignition cut after the MAP sensor is maxed out? Or does the ECU just run the values set at 20 psi?

Im guessing I should make the 18 and 20 psi cells a few steps richer, to compensate for 21-22 psi.

 

it just runs the car at the values in cell at 20psi.

Also do another thing.

Put a 1/4 inch fuel filter in your Vaccum line. It will settle the signal down on your vaccum line going to the microtech and make its better tune!

 

Damn, really? I will definately try that! You mean one of those little cheap universal carburetor filters, right?

 

yep.
SOmething ive been doing recently.

Lets you be able to pinpoint bad spots in the tune without having to change a whole section of it.

 

So if I want to run 25 psi with 2 bar map sensor, I can just max out the injector ms at the 20 psi tuning point?

 

YEP
But that means when its actually at 20psi it will be rich.