this may be stupid--but is the baro sensor influenced by its location on the car. The ""weather" (pressure and temperature) under the hood is clearly different than outside?
Should the barosensor be placed outside the engine bay? Or is it more important to keep it in the same environment as the intake?
OD

 

Pressure, will be the same. temperature does not influence the baro sensor. at least not directly. Technically, pressure is directly proportional to the temperature

But the baro sensor's purpose is for measuring pressure and only. it doesn't measure things like relative humidity, temperature, oxygen content(as if you drove into an area with no oxygen(thats why we have oxy.... nevermind thats going to confuse the **** outta someone). pressure can change daily and does. i forget that factor.

 

i guess there is not enough of a pressure differential inside the engine bay to affect the sensor? I do wonder if vented hoods or the folks that pull the downward deflecting stuff from the engine fans could affect that sensor . Maybe in theory only?

If you unplug it and you are not at sea level then the ecu will pull a little timing and the a/f's may be a little richer--right?

 

Glad to see one of my threads finally getting some use! ^_^

 

Yes, it is error correction. That is sort of my point. The MAF can measure the mass of the air, but the load calculations on a fixed volume system need to be corrected for the mass that volume is capable of.

 

so what if we just set the fuel map for 220 calculated load?

 

Can only set to max load of 2

 

No, it will go to 4.00.

Something about Klein Bottles and tesseracts come to mind...

 

Ok, I get that

yeah my max calc load only goes to 2.0
but the scale on the air fuel map will go to 10.00 lol

is the calculated load on a datalog the true calculated load the pcm is using?

 

please explain.....you can set calc load max to 4.00?

 

No. Fuel tables.
To 10.00 apparently on some versions of RACETuner.

 

Ah.....thats different

 

Well you need to use that if you are making that kind of power. Contrary to some earlier comments, the system will interpolate between two points. However once you go past the last point you lose the outer point to interpolate against. So the system goes flat and only maintains the last point on the map. It does not maintain a slope between two points because unless you made a second outer point it then does not exist and has nothing to maintain a slope against.

 

Huh?

First of all, you will never "make enough power" to exceed the edge of the paper as we have discussed.
Second, the interpolation follows the delta of the last two axis references, so whatever that delta was would describe the next point that is of equal granularity to the previous value.

 

That was not my experience nor necessarily an accurate assessment of the realities that occur. If you set your rev limit to 9800, but your fuel map is still set for 9000 rpm at the last map point you will find that it can be tuned correctly for either 9000 rpm or 9800 rpm, but not at both or all points in between without restructuring the map to operate out that far.

 

If you set your rev limit to 9800 and your last fuel value is at 9000, the calculated injection value will be on the slope outlined between 9000 and the value before it.
Remember that fuel delivery is not directly correlated to the commanded value since injected volume doesn't directly follow pulse width.
As you approach the maximum available duty cycle, each additional time fraction doesn't actually equal the same amount of fuel as the same preceding time fraction.

 

What Jeff is saying is you can determine what the ECU has in the fuel map for 9800 via interpolation of the delta from the values in last two rpm cells (ie 8500 and 9000). Never said the engine will output what that value is without tuning for it.

 

I understand what he said here and in the two tuning webinars I attended. You clearly do not understand my reply.

 

Then explain yourself more clearly as he seems to have responded correctly to what you posited.

 

finally - some info we can actually understand - only took 6 months

 

For the sake of argument I am willing to concede that minor point about maintaining a slope, however as I previously asserted that slope is not necessarily correct for operating past that point or points in between and you will not get the correct results without restructuring the map to operate over that entire range. It may not show up on lesser NA applications, but again on my personal NA application with many unique custom parts my assertion is well proven.

 

I already addressed this question back in 2007.

That might be true of the interpolated values below the top row as well,
That is why you have so many overlapping correction tables.
The Ve of the engine is always changing as the RPM changes. I think it is pretty safe to say that the Ve is diminishing at a somewhat unknown rate up there. Simply continuing to add fuel at the same rate as the earlier cells that might not be diminishing as quickly is going to produce unwanted results.

 

Thank you, that is all I am trying to point out. You cannot assume the last point on the map is going to cover more than one particulr point between the last map point and the operating point that you extended out past it too. The further out you go past it the more likely this will prove out.



.

 

good work - obviously EVERYONE read it and fully understood it

 

Well, it is only obvious that you did not. Beyond that, I cannot certify...

But that is understood, just as you cannot be certain (and in fact, it is definitively uncertainty) that the fuel requirements at 6250 will be met on the slope between 6000 and 6500.
That is the "hedge" we discussed and the reason for the Ve map (amongst others) and the need to nail the MAF calibration.