Do MAFs adjust richer as gears go up? Tuners & members please respond: Truth Squad
 

TPP posted that there is no way around our stock MAF setting AFRs a little richer in each successive gear. Is this true? If so, does the change richen up the AFR's enough to even matter?

Here is what what was said:

Well, you want it to richen up when load increases and it does richen up to protect the motor. I'm not sure what you're getting at with this. :confused:

My answer here:

https://www.evolutionm.net/forums/sh...55#post2621655

dryad, are you telling the truth?

Yes I am

With turbocharged cars, the maf or map sensor is obviously the preferred reference for load as we all know that the throttle position basically means next to jack with a turbo hanging off the side (short the accel enrichment, etc, etc). With that said, yes, as you run through each progressive gear you will generate more load as well. As to whether or not you run richer in each successive gear depends on the mapping in the ECU and what the factory does as the car encouters those higher loads. So is the question does a stock ECU in the evo enrich in each progressive gear? I'd say yes, but I'd think its not really concerned with the gear, but rather the ecu enters those higher load cells in the same rpms in addition to the increased coolant temps associated w/ WOT through a few gears.

{thumbup}

I know when i use to tune with LS1 Edit the MAF would make small adjustments as the gears went up to accomodate for the load but that was with a draw trough MAF not one of these weird Vortex Units.

Not only that but i was also able to set the rate of adjustment in each gear within the MAF tables.

Don't know if it helps much.

I try ans Stay away from MAFs as much as possible speed density is a much better way in my opinion.

I was the First LS1 Stateside that used a speeddensity tune (thanks to some helpfull tuners down in australia who have been doing it for abot 3 yeras now)

The MAF only reads airflow which really is a measure of load.. your engine management uses that information along with air temp, TPS, engine temp, etc to calculate the load on the engine, which is higher at each higher gear, the maps are generally based on load and RPM and therefore will adjust richer based on the higher load it reads, however its not directly a factor of the MAF, and "Raising the maf reading" using an S-AFC or any other device that changes the MAF output, raises or lowers the percieved load which in turn would alter air fuel ratio or timing indirectly.

If speed density was the best tuning option for street cars (and it isn't), manufacturers wouldn't go through the extra expense of using MAF-based systems - and they all do.

Speed Density is a simplistic concept, and is most applicable for a static system. 'Static' can be defined as that which does not change, and this applies to engine hardware, altitude, engine wear, weather, etc. Obviously, one can encounter any or all in a street vehicle over the course of many thousands of miles. In short, speed density is relatively 'dumb' because it relies on assumptions. It certainly can be used in street applications, but there are limitations that must be accepted. Furthermore, it's been demonstrated here there is no discernable power detriment to using a MAF in a 500+whp EVO, so the notion that speed density 'makes more power' is speculative and baseless within 99+% of typical EVO applications.

As noted above, a MAF makes a direct, real-time measurement of engine load, which is essentially corrected volumetric efficiency. If there is an A/F fluctuation in higher gears, it isn't due to an imaginary shortcoming inherent to MAFs. It is due to programming, which is entirely the result of human input, and is easily changed.

MAF based systems are the best for Reliability, drivability, and Gas Efficiancy.

However the MAF becomes a restriction @ high horsepower becuse of the limited range a maf can read.

True.


That is true, but since this has been demonstrated not to be the case for the EVOs up through at least the mid 500hp range, this renders it effectively a non-issue.

Assuming you are using the one data point from a recent post here, it is pure speculation to say that a speed density system makes more or less power than a system with a MAF sensor.

Absolutely, there are issues with the stock MAF, however their not really a restriction issue, but that the Evo's MAF is based on aerodynamic principals that can be upset by moving more air than its designed for, or causing turbulence. There **ARE** very good alternatives out there besides Speed density. Which offer the ability to read airflow required for 1200cfm (600 or more whp) and aren't based on aerodynamics which are prone to error at air velocities that high.

With that said, 90% of ALL The evo's DON'T NEED A SPEED DENSITY or even an upgraded MAF CONVERSION.. sure its nice, but most are doing it for the wrong reasons, and you do sacrifice the flexibility and drivability that a MAF system offers.

As far as I can tell, most of the people obcessed with speed density, seem to be focused on VTA BOV's or have made changes to their cars that they can't work around with the tools they have available.. Which is totally understandable, but not the right reasons.

Thats where i have found the problem to be is in the design of an intake pipe for use with GT series turbos that simulate the airflow pattern of the stock pipeing.

On of the best MAF's i have ever used is the GM. 78mm MAF out of the 02 and newer ZO6 it can support 800 whp effectively, only probelm with it is it's composite contruction causes it to "explode" if the BOV does not open quickly enough. (this happend to a car i was tunning with 15psi on a Procharger F1C)