Would've thought someone would answer by now...hmm.
Well, while I haven't specifically tuned Corvettes, I have tuned multiple types of engine management systems...both standalone and reprogrammed oem ecu's. So, its my feeling that the same info should be the case here. That's my disclaimer though just in case.
The IAT (intake air temp) which is the same as whats being discussed here, does allow the ecu to compensate for changes in air density with both parameters being controlled. In all the ecu's and standalones I've tuned, IAT or manifold air temp, has influence over fuel and spark advance.
Now, where it may change is the amount, as some motors tolerate varying conditions differently due to combustion chamber shape, fuel system type, etc. In the systems I've worked with though, your generally look at 0 change at around 100f, then about -3 degrees at 130f, then about -5 or -6 degrees at 160+. Fuel wise, it subtracts maybe 6% at 160F+ and adds a good bit as temps go below freezing.
Knock generally has a big influence over timing, but not sure if you have that or not. Depends on how much timing retard your talking I suppose that may point to whats happening.
Would've thought someone would answer by now...hmm.
Well, while I haven't specifically tuned Corvettes, I have tuned multiple types of engine management systems...both standalone and reprogrammed oem ecu's. So, its my feeling that the same info should be the case here. That's my disclaimer though just in case.
The IAT (intake air temp) which is the same as whats being discussed here, does allow the ecu to compensate for changes in air density with both parameters being controlled. In all the ecu's and standalones I've tuned, IAT or manifold air temp, has influence over fuel and spark advance.
Now, where it may change is the amount, as some motors tolerate varying conditions differently due to combustion chamber shape, fuel system type, etc. In the systems I've worked with though, your generally look at 0 change at around 100f, then about -3 degrees at 130f, then about -5 or -6 degrees at 160+. Fuel wise, it subtracts maybe 6% at 160F+ and adds a good bit as temps go below freezing.
Knock generally has a big influence over timing, but not sure if you have that or not. Depends on how much timing retard your talking I suppose that may point to whats happening.
I also see some knock retard too. However, it doesnt account for all the spark retard I see. If I set my timing at 25 degrees and run at WOT, a scan might show I saw 17 degrees timing, and 4 degrees knock retard. What is not accounted for is a remaining 4 degrees of timing retard that comes from somewhere.
Its my belief its coming from my air temp sensor. Im considering relocating this to ambient air temperature and relying upon my tuning to account for this.
Sounds pretty possible based on what I've tuned. Hot air is hot air though...less dense=less power and hot air means more knock prone. I don't think just disabling it by accessing it to ambient air is the answer, but it's really gonna come down to the fuel your using and what the motor is gonna tolerate. You may simply remove the mat sensor and gain knock, and then be right back where you started. A better approach would be doing what you can to reduce those air temps.
Yes, sometimes its ok to leave well enough alone. Getting tunnel vision based on a particular power number always ends bad. 150f isn't bad, but isn't great either, but considering its supercharged....yeah it aint' bad.
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What is being controlled by my MAT (manifold air temp) sensor? 93 lt1 ?
