antus wrote:Actually air temp makes negligible effect on air density for purposes of fuel tuning. Air quantity is relevant but the MAF does handle that and output the correct data. Air temp is needed for spark timing as hot air will detonate sooner. I did think that density made a difference too, but then I did an efi-live tuning course and they set me straight on that.
I just had a thought? Does MAFs contain a temp sensor built in for the purpose of correction of the output of the MAF itself?
As a general overview of mass sensors wiki to the rescue: https://en.m.wikipedia.org/wiki/Mass_flow_sensor
There have been many types, from the old spring loaded trapdoor to the modern card type.
antus wrote:Actually air temp makes negligible effect on air density for purposes of fuel tuning. Air quantity is relevant but the MAF does handle that and output the correct data. Air temp is needed for spark timing as hot air will detonate sooner. I did think that density made a difference too, but then I did an efi-live tuning course and they set me straight on that.
I just had a thought? Does MAFs contain a temp sensor built in for the purpose of correction of the output of the MAF itself?
Yeah they do, that was what i was getting at to begin with...
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vlad01 wrote:not according to my understanding of physics, air density changes a significant amount.
Take air speed into consideration, that is why I "agree" with Antus' previous post. Yes air density changes but air speed is high enough to not let it change alot thus the effect on fueling may not be as much as you and I would think.
Can you show the equations and your workings?
I never claimed to have an equation or workings. What I am saying is the air is not subject to heat for long enough for it to change drastically. Consider how fast the air is flowing into the engine and how much time it would take for a change in temp and the corresponding change in density to occur. Density changes because of expansion (heat causes expansion) but the 2 things do not occur simultaneously so the air could heat up but not enough to change density. Remember between the throttle body and the inlet valve the tract is virtually a closed system.
vlad01 wrote:I just had a thought? Does MAFs contain a temp sensor built in for the purpose of correction of the output of the MAF itself?
Yeah they do, that was what i was getting at to begin with...
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In this instance it is only used to calculate how much air is flowing into the engine. In later MAFs the air temp sensors also do the exact same thing as the IAT and MAT do.
It is all about tooling and cost.
antus wrote:Actually air temp makes negligible effect on air density for purposes of fuel tuning. Air quantity is relevant but the MAF does handle that and output the correct data. Air temp is needed for spark timing as hot air will detonate sooner. I did think that density made a difference too, but then I did an efi-live tuning course and they set me straight on that.
I just had a thought? Does MAFs contain a temp sensor built in for the purpose of correction of the output of the MAF itself?
Yeah they do, that was what i was getting at to begin with...
Was good to get some different opinions on it all. Reminds me of something I've thought of doing. I plan on getting set up to tune LS1's in the near future and have thought about re locating the IAT sensor into the intake as per a proper MAP based system. When going MAFless obviously. Not sure how flexible the software is in that area on those PCM's.
