Airbox sensor

[danl]

oops, I was just re reading and noticed that I had repeated exactly what jtucker wrote in one of his posts. Sorry for the plagiarism Jason! I hope it won't hurt my political career.

[dlaing]

It's more or less pure mathematics with ancient physical algebra. Warmer air has less density. To keep the air/fuel ratio (by weight) constant, the ECU must inject less fuel at warmer temperature (and also at higher altitude, for the same reason).

 

Sadly, our bikes, like any normal aspirated engines, will perform their very best at temperatures so low we don't dare using it

 

An exemple of remedy for the problem is a charger like this one

That super charged bike would be nice, but getting back to what I am more likely to try, would it make sense to add fuel for cooling rather than following the physics of maintaining a given Air:Fuel ratio?

FWIW, I more likely to change the engine temperature fuel modifications, before changing the air temperature modifications....

According to TuneBoy, here are the fuel modifications for the two temperature sensors:

 

air temperature

 

engine temperature

(EDIT: it looks like air temperature could be in Fahrenheit and the engine temperature could be in Celsius, but I think they are both celsius?????????????)

[raz]

That super charged bike would be nice, but getting back to what I am more likely to try, would it make sense to add fuel for cooling rather than following the physics of maintaining a given Air:Fuel ratio?

FWIW, I more likely to change the engine temperature fuel modifications, before changing the air temperature modifications....

I think I heard some systems do that to a degree. I don't think it will help the power loss at warmer air temps though, just save your engine on the drag race strip.

 

According to TuneBoy, here are the fuel modifications for the two temperature sensors:

 

(EDIT: it looks like air temperature could be in Fahrenheit and the engine temperature could be in Celsius, but I think they are both celsius?

I'd hate riding at 125°C ambient for sure

 

As you can see, they didn't bother putting in any more decrease above 41°C, that makes sense in Celsius.

 

FWIW here is the air table from MyECU as delivered. This one also goes all the way to 125°C but no values is given above 50°C:

# AirT is the barometric adjustment for air temp (based on ideal gas law)
#Temp C   -30   -20   -10     0    10    20    25    30    40    50    60    70    80    90   100   110   125
AirT%   +24.7 +19.8 +15.2 +11.0  +7.1  +3.4  +1.7  +0.0  -3.2  -6.2

[luhbo]

I'm quite sure it takes the last given value to fill in the empty ones (above 50 deg).

 

Adding extra fuel to keep engine temperature in an acceptable range at higher ambient resp. head/oil temperatures could make sense, but only on first sight I'm afraid. It will cool down he head a bit, surely, and also it will help to reduce pinging. But the downside is, that these effects are a problem only under high engine loads. The enrichement would nevertheless affect the entire map and I can see no good reason for that, actually. Give me a good reason and I will change my map.

We're not using our bikes for racing, and some not so develloped countries still don't have these lovely high speed autobahnen on which you could ruin an engine on very hot days

 

Hubert

[dlaing]

We're not using our bikes for racing, and some not so develloped countries still don't have these lovely high speed autobahnen on which you could ruin an engine on very hot days

I did a track day and I am pretty sure I took a few years off of my bike in just one day.

If the A:F ratio was set across the board to 12.5:1, assuming maximum power was THEORETICALLY at 12.5:1, and the temperature compensation curves kept it there, I guess that would be OK. But, I think more optimal A:F might be leaner than 12.5:1 at cool temperatures, and richer than 12.5:1 when approaching the hottest temperatures that we might face.

Leaner when cool should improve fuel consumption, reduce emissions, reduce carbon build-up, and help the engine warm up.

Richer when hot should act as a safety against overheating related issues, mostly when working the motor hard, but I believe also in other conditions like Summer traffic jams.

[dlaing]

As you can see, they didn't bother putting in any more decrease above 41°C, that makes sense in Celsius.

Yah, I might consider modeling the map more after the My15.