Running a gutted stock MAF with the flash ECU.

[Greg E]

This is actually quite easy to tune! Well when you gut the MAF, quite literally more air goes around it. This means that each pulse stands for a greater airflow number. All you have to do is adjust the MAF Adder value for this extra air. Leave the MAF Scaling table alone.

To keep your injectors and fuel table accurate, you just need to adjust the MAF comp values. How much or little can be calculated easily with the fuel trims and a wide band.

Live tuning would be very helpful for this...

[Blackmount]

Subbed- Also This is why alot of people who "gut" their maf's usually end up having running issues later down the road? (Because of scaling)

[Greg E]

Well... When you gut the MAF you should be able to fine tune it with any 1% increment piggy back. The thing is though, who know what air turbulent effects this has on the MAF. The reason this only works "okay" is because you're not telling the ECU to add/take away fuel, you're increasing or decreasing the HZ value the ECU sees so you have to speed it up or slow it down into an area in the MAF scaling table where the look up has the correct value you need.

To further complicate the issue, remember there's is the MAF smoothing table which is yet again another correctional value multiplied after the scale and adder are combined....

The only reason people have had decent luck with it is because closed loop works well enough at fixing all the airflow errors you get as a result of this setup.

[futurevr4man]

So do you think people running blow thru with a maf-t may need to rescale our mafs slightly? Maybe the lower resolution is off which is causing our lean spike? Maybe I should post in the other thread...

[Greg E]

Yes. You must do this even when running the stock MAF. Hard intake pipes, innercooler, bigger turbos, exhaust, head work... All those things change your engines particular VE. Not even getting into engine wear... This is why no tunes can be copied into another car and keep the fuel trims happy. Every engine has a different VE curve.

[Greg E]

In the case with the MAFT, the GM sensor reports much less airflow than a stock MAF meaning your HZ numbers are usually lower than what you would see out of the stock MAF. So right off the bat, your scaling numbers aren't accurate anymore.

[futurevr4man]

Hmm. I haven't even touched the maf smoothing table yet.

[futurevr4man]

Would a logical test be:

Hook up stock maf, datalog and record airflow from a constant source (hair dryer) then do the same test with GM maf/maf-t and compare/adjust?

[Greg E]

What I did was leave the stock MAF, ran a 3rd gear pull (on the road in front of my house), then let the car idle.

Then I swapped in the MAFT (draw thru) left it zeroed out, ran 3rd gear on the same exact stretch of road, logged idle again. The HZ readings were lower.

With Toni's car (MAFT in blow thru) his car sees even less airflow than mine did. For reference my 9b car was pushing 220load when I did the 12.87. Toni's car was seeing only 190 load and his car ran a 12.5.

There is no way his car is pushing less air than mine. It put down 450whp...

[futurevr4man]

But I cannot run on stock maf, not really an option on my build. I figured comparing maf values to maf values is reasonable though