Tuning MAF to give SD Throttle Response
#21
TECH Addict
iTrader: (3)
[QUOTE=kingtal0n;19360886][QUOTE=moehorsepower;19360071]
the maf is the sensor/meter (mass air meter?) that measures these things. It show in the voltage graph. You simply log the maf output and look at it with ur eyes and judge for yourself if it looks all fucked up or if it looks nice and smooth.
Never mind, we will never get a straight answer, ok the output is either smooth or jagged, My question was your answer of, air perturbations and shock wave, You try to hard to post what I call exotic wording instead of just basic understanding like swirl, tumble or turbulence. but please dont answer, Im done with this thread...
the maf is the sensor/meter (mass air meter?) that measures these things. It show in the voltage graph. You simply log the maf output and look at it with ur eyes and judge for yourself if it looks all fucked up or if it looks nice and smooth.
Never mind, we will never get a straight answer, ok the output is either smooth or jagged, My question was your answer of, air perturbations and shock wave, You try to hard to post what I call exotic wording instead of just basic understanding like swirl, tumble or turbulence. but please dont answer, Im done with this thread...
#22
Banned
iTrader: (1)
[QUOTE=moehorsepower;19361422][QUOTE=kingtal0n;19360886]
the maf is the sensor/meter (mass air meter?) that measures these things. It show in the voltage graph. You simply log the maf output and look at it with ur eyes and judge for yourself if it looks all fucked up or if it looks nice and smooth.
Never mind, we will never get a straight answer, ok the output is either smooth or jagged, My question was your answer of, air perturbations and shock wave, You try to hard to post what I call exotic wording instead of just basic understanding like swirl, tumble or turbulence. but please dont answer, Im done with this thread... I go out of my way to use small words. I didnt realize shockwave was not in your dictionary, nor is it exotic in my experience, in fact it may have been chosen poorly often I am just typing these replys out quickly without proof reading. I am not sure turbulence or swirl would accurately describe what happens when the throttle valve slams shut. Turbulence really doesn't mean anything to me- the maf itself is a source of turbulence, yet we do not complain or worry about the turbulence that it creates because we assume the designers knew what they are doing. the same goes for any turbulence in the intake manifold and so forth, so it is inadequate for our measures. The air hits a 'wall' and because it has mass and behaves like it has mass, the air molecules behind the ones that 'shock' the throttle body (perhaps elastic collisions is the 'exotic' term I am leaving out?) may collide with whatever molecules just hit the throttle body and so forth, and moving backwards momentarily as the pressure spikes as high as it can in that region for an instant, thus you have a 'shock wave' of 'pressure spike' yes I believe this is accurate, more so than other choices but maybe we should both look the definitions up at this point to be sure because I have been known to create new definitions for words without realizing it (it was the intended purpose of the usage, not the actual dictionary definition, I go by so disclaimer: ask for clarification in NON technical discussions, which is what this is really). The pressure spike is brief, whatever else you call it that is close enough. You can see this spike when you let go of the handle from a pressure cleaner in water line, or when the you shut the throttle body suddenly, and it may even register on the map sensor slightly if you have one. The reversive nature of the pressure spike is short lived because A: the engine is still breathing and B: the other end of the pipe is not sealed, so air can exit via the air filter (and pass through the compressor wheel thus the compressor surge). However if there is any sensitive measuring devices in the region, it will falsely fuel the engine based on that pressure spike, which acts as a wave from the point at which it was created, "wave" with the hopes that it will impart to the reader a sense of organized pressure differentials with individual scalar quantities per unit space, you can go thesaurus up an easier word if you want for that, and it is similar I would guess to what happens when a firecrackers pops and you get a 'shockwave' in the air, a series of specially organized mathematically describable waves that are 'shocking' the air into moving abruptly in that pattern. I am not sure if this will exceed the speed of sound or attempt what velocity, but I believe that the physical appearance as the air molecules are concerned, there is a high/peak point (the air molecules closest to the throttle body would be the tightest packed for an instant and have a highest scalar physical quantity pressure) and a gradual sloping patterned overall decrease as one moves away an infinite distance from the high point, 'wave' is also correct whether the system is closed or there is a steady state (on the other side of the TB, the engine could now be 'at idle steady state' which means some quantity of air molecules per unit time is being taken up to pass the TB, which is removing molecules from the 'pressure spike side' quickly at approaching infinitely thin slices with respect to the throttle valve, while they are reversing out of the intake tract at the same time, depending how much pressure was in the 'cold side' when the TB slammed shut) Remember that the user might shut the throttle valve at any engine RPM, so we are assuming this is a traditional air-tight throttle valve. Remember that drive-by-wire is open partially at idle, so keep in mind not all throttle valves will be sealed shut completely (holding water at least) at idle speeds and I have a feeling that will influence this whole situation. Perhaps this is one more reason drive by wire was found to be superior.
the maf is the sensor/meter (mass air meter?) that measures these things. It show in the voltage graph. You simply log the maf output and look at it with ur eyes and judge for yourself if it looks all fucked up or if it looks nice and smooth.
Never mind, we will never get a straight answer, ok the output is either smooth or jagged, My question was your answer of, air perturbations and shock wave, You try to hard to post what I call exotic wording instead of just basic understanding like swirl, tumble or turbulence. but please dont answer, Im done with this thread...
Last edited by kingtal0n; 08-17-2016 at 02:35 PM.
#23
12 Second Club
iTrader: (13)
This may be other than what you think, because when
MAP jumps (like tip-in) you are temporarily put into SD
mode (the "unsteady MAP" criterion) anyhow. Because
the MAF is indeed slow and will report yesterday's news.
I'd look for other things, like SD being so different from
MAF airflow that you're getting tip-in KR or something -
or that difference, with everything trimmed in to what
steady state MAF is doing, is putting you at a bad mixture
position when you pop to SD (presuming you're still in the
same trim cell).
MAP jumps (like tip-in) you are temporarily put into SD
mode (the "unsteady MAP" criterion) anyhow. Because
the MAF is indeed slow and will report yesterday's news.
I'd look for other things, like SD being so different from
MAF airflow that you're getting tip-in KR or something -
or that difference, with everything trimmed in to what
steady state MAF is doing, is putting you at a bad mixture
position when you pop to SD (presuming you're still in the
same trim cell).
#24
Banned
iTrader: (1)
I hate to derail this thread even further, but the only way the conclusions in your provided link would make any sense would be a MAF installed pre-turbo. I can't imagine a scenario where that would be a good idea. Then again, placing a MAF post-turbo usually isn't so great on LS based platforms so...??