Bulvot

I'm working on tuning with a new turbo. I found something that isn't documented and doesn't make a lot of sense to me. Most likely due to my ignorance on the topic.

In SharkTuner, if I create anew EPROM and select the SuperMAF, the fuel map MAF axis only goes to 236 by default. If I manually edit it, I can only raise it to 300.

If I create a new EPROM and select the regular MAF, the fuel map MAF axis defaults to 516, same as displayed in the manual.

So, what's the deal? Does the SuperMAF top out at 300 so I need to adjust the fuel map MAF axis to fit within that range? Or, is there a problem with the SharkTuner software? Or is there a setting somewhere that I'm missing?

FredR

The supermaf is calibrated differently. The software selector switch in ST2 tells the system all its needs to know so that the brains can figure out what is going on. I am pretty sure that what you are seeing is perfectly normal and nothing to be concerned about but doubtless John will confirm that for you.

With the stock MAF the output signal maxxes out on the LH unit at around 400 bhp so the MAF can still generate a signal but the LH cannot read it. The load number generated does not really matter, what does matter is how the brains understand the number generated thus the calibration factor. Hence the supermaf can read airflows somewhere in the region of twice what the stock unit can see.

Bulvot

I know that, it's in the manual. However, what isn't in the manual is what the max numbers are that a SuperMAF can deliver. I'm seeing 263 at 4k rpm and 10psi. Far above the default max of 236 that the supermaf map sets itself at.

I need hard numbers, not general theory

Bulvot

And the answer is...the SuperMAF can probably read a little above 236, but it really shouldn't.

ptuomov

There's the Bosch MAF element technical spec that gives you the range over which the MAF sensor in the 928 housing is guaranteed to be accurate. The maximum by technical documentation is 930 kg/h. As you exceed that air flow, the probability of the sensor going out of range increases, and the point depends on the operation conditions. John Kuhn, Jim Corenman, and John Speake can all give you their estimates of how far above the 930 kg/h the sensor can actually measure in most circumstances.

John Speake

In excess of 2000kg/h

Bulvot

To provide a little context, the SharkTuner logs were reporting some very high numbers from the MAF, combined with some very rich running conditions, and a max MAF voltage of 5.11v. There was significant power loss corresponding with the high MAF numbers and higher RPM and load. I started with the simple question of "are these MAF numbers right" and ended up down the rabbit hole of conflicting information from multiple people.

In order to properly determine the problem, I needed to know what numbers should or could be showing up in the SharkTuner logs. The manual doesn't address the SuperMAF numbers, and I was receiving conflicting information from others, so it was hard for me to determine the correct parameters to make an assessment from.

But, I now know for certain that the SharkTuner logs will never show a MAF voltage above about 5v, even with a SuperMAF installed. So that understanding of "normal", eliminated a major data point that had been causing me some confusion. Also, knowing that the SuperMAF can report numbers above 236 but shouldn't normally do that with my power levels, further helped eliminate the SuperMAF as being the problem.

The SharkTuner manual doesn't address this next point, but I now know that the MAF axis is supposed to be defaulted to a max of 236, versus the 516 shown in the screenshots of the normal MAF axis points. And while you can raise it to as high as 300, that really shouldn't be necessary for most situations (including mine). But, that difference again caused me some consternation when I received advice that something was wrong and I should have MAF axis points going up to 516 with a SuperMAF installed and I was advised to manually edit them to achieve that configuration. Which is impossible to do when you have the EPROMs configured for a SuperMAF.


Bottom line, the SuperMAF seems to be working properly, the SharkTuner software is awesome, and the MAF axis for a SuperMAF defaults to a max of 236 because the SuperMAF should be reporting numbers below that in most situations. It can report higher numbers, but shouldn't be doing that for most situations under 600hp.