I have IJEOS MHD MBoost option, N20 option checked, N20 TMAP. ... I should to be able to measure boost pressures higher than 22 psi but this log clearly shows the boost pressure being clipped at 22 psi ...
How do you get the data logging to report more than 22 psi?
Having read through the three pages of responses I felt many readers would have a difficult time getting to a straightforward answer to the OP's question. I'm going to try and boil this down a bit. There are three steps to getting MAXboost working:
First...
You will have to voltage scale the map sensor.
And here are the two maps in TunerPro for doing that:
I have it like this with n20 sensor
Next, you do this...
I use the check box in the flash time options also, kinda thought it was required to get the logging boost pressure correct.
He's talking about the checkbox for the N20 3.5bar MAP sensor that's in the "Options" submenu during flashing.
When using the 3-cell scaling table, the stock 2-cell table is ignored.
That's why you can have the "2-cel" MAP conversion map zeroed out.
Then, last but not least, you need to make an adjustment to the "Logging Options". In the submenu for measurement units, you will also see a checkbox to activate MAXboost logging. Be sure that's checked.
Once you've done all three, your logs will be able to record boost values right up the ~37psi limit in the 3-cel MAP conversion table.
So, how well does this work?
Also, that 3-cell scaling is slightly off (it has been shown vs. an external sensor to be 1-2psi off depending on boost). I am working on fixing this.
I ran some tests on this question. And here are some graphs to show what I found. First is a comparison of readings collected through the two MAP conversion tables.
As you can see, the boost readings do read higher with the MAXboost scheme. But is that an inaccuracy? Our test car has a WMI controller by a company called Torqbyte. This controller has its own dedicated TMAP sensor, which receives boost signal from the manifold plenum. Because the Torqbyte software has a calibration feature, its readings for boost post throttle body are very accurate. Let's see how the MAXboost stacks up there.
Here is the Torqbyte's TMAP reading versus the MHD logger's value of "boost mean"
Again, it's reading a little high. But the "boost mean" value from the N20 TMAP sensor is a measurement from UPSTREAM of the throttle body. The Torqbyte sensor is reading manifold pressure. So the more fair comparison would be to the MHD value "Boost PSI". And here it is:
Pretty accurate, I'd say.
One other thing also talked about:
FYI, playing with this stuff without understanding everything fully is a quick way to an early n54 death. Might want to pay someone to rescale all your load based maps.
Boost, Boost Mean, and Boost Target will all log as scaled when using the 3-cell TMAP table. You can see it is working correctly, since your boost target is 24.2psi. In unscaled form, max boost target is 21.X - 22.1ish psi based on your local baro.
The DME's calculation for load DOES change with this modification. Here is the before/after:
Here is one last graph comparing the change in boost target values. As said above, the DME now calculates much higher boost targets for equivalent load requests.
Hope this helps.
Doug Harper
FrankenTurbo