bob13bt

iTrader: (9)

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?

myfc3s

iTrader: (2)

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

rx72c

iTrader: (8)

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

rxspeed7

iTrader: (5)

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

rx72c

iTrader: (8)

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.

bob13bt

iTrader: (9)

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.

rx72c

iTrader: (8)

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!

bob13bt

iTrader: (9)

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

rx72c

iTrader: (8)

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.

RexRyder

iTrader: (10)

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?

rx72c

iTrader: (8)

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