claykos

Longshot, but does anyone know the correct multiplier factor to put on the "fuel used (raw)" channel out of the MS 3.1 ECU for use with the Motec fuel prediction? This is specifically for a 996, but I think the value should be the same for every year since it's a function of whatever units it comes out of the ECU in. I found some information online for the MS 4.3 ECU that the correct multiplier is 45.8 to get from the raw ecu value to ml. Not sure if it's the same for a 3.1??

tedean

This drove me nuts just because I wanted to figure it out. Due to racing only 30 minutes sprints and 60m enduros, I really don't use it, but still wanted to get it close.

Method: Incrementing Fuel Used Value
Raw Fuel Used input channel: Fuel Used (Raw)
Fuel Used = (raw channel + 0) x 10/1

and I set an alarm reset Alarm Acknowledge True (for 10s).

You really have to weigh your fuel in and out to get the numbers close. My values get me pretty close.

Oh, this is in a 997 Cup and these are values I put into MoTec's ADL2. Not sure if it help you.

claykos

Thanks! I don't *really* need it either (just do sprint races), but I just wanted to get it working. Guess I'll start with 10, and check from there.

HiWind

subscribed ... been puzzled by this on the ADL2 and MotecM84 myself ... ie numbers have been meaningless

Viperbob1

My partner here with an 08 Cupcar has been messing with this for over a year. He thinks there is some magical way that it will work. PMNA guy at Sebring told him no (I have been telling him for a year). I have been making small adjustments to that equation and was pretty much there. Then the owner decided that if it came at 10 it must stay at 10 (so deleted my modifications) and then just wants it to mysteriously work

amso3

I have at least 10 dash configs in my laptop. All have 10 as the multiplier

HiWind

thanks Jerry!

tedean

When a friend told me it would not work, I was more determined to figure out why. It works based on injector timing and fuel flow through each injector. Given a constant fuel pressure, the timing if each injector opening, flow of each injector and quanity of injectors, you can predict the fuel usage. Makes sense. The math does not makes sense so I started guessing. It is fairly accurate, fairly being the key word.

georgemcf

I had a play round with this a while ago. After going round in circles I had a chat to the motec engineers about it.

The only way to get it accurate is to weigh the fuel in the tank, go for a run and then weigh what is remaining. Then you can see how far off the calculated vs measured numbers are and then adjust the equation accordingly.

I gave up when the equation in my 2010 cup was close enough that i never ran out of fuel. And that equation had 10 as the multiplier.

Matt Romanowski

You have to weight fuel in and out, along with adjusting for fuel temp as the density changes.

Tommy - this is in the materials from Jorge in the Race Strategy section.

tedean

HA! Matt, you are correct, forgot, p324. I am working on the TPMS and ideal gas laws.....so had not returned to that yet. Thanks!

MoTeC Joe

Jerry is correct, these numbers are money. You can take the fuel used values to the bank as long as nobody has increased fuel pressure or changed to different injectors. My fuel strategies depends on accuracy and I have confidence in these numbers. If somehow you are not getting a accurate reading to the pumpout volume, check to see if the lift pumps are actually pumping out all the fuel. The lift pumps do fail.