But isn't the point of Mivec to give you more power AND improve fuel economy at the same time?

From Mitsu:
In the pursuit of pure driving enjoyment, potentially incompatible goals like fuel economy, environment-friendliness, and clean driving have all been achieved.

 

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Translation:

under 3500 RPM = better mileage

over 3500 RPM = more power

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Maybe the AT runs under 3500RPM at 80Mph... but yeah, mine is way over 3500RPM at 130 Km/h (80 Mph).

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Okay guys... well I'm off on vacation! I'm out the door at this very moment... Thanks for the info... and I'll let you know what I learned from my MIVEC testing.

Back in a week!

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yeah for auto it runs like 3100-3200 rpms at 80 mph for me

 

yeah! what he said! ^

 

there is a reason why us Auto Ralliarts are engaging the mivec at higher speed that you 5speed guys....our ratios are different and our final drive ratio is higher ...for a full comparison of ratios go to generationmivec under "newbies check in here first " the easiest way to find specs thanks to Diamondwhite...

 

Better fuel economy below 3500 (the intake valves open at inequal lifts, to swirl the intake air/fuel, for better combustion). After 3500, they both open further so the air/fuel can get in easier, so it pulls MORE air (and thus, more fuel) in after 3500. Increasing power, but also wrecking gas mileage.
As for autos, they don't hit 3500 until after 80MPH. Mostly because of the final drive (the final gear, 4th in the autos and the final gear, 5th in the manuals is a similar ratio, I think.)
So it's weird, the autos have a higher top speed too, even though they have 1 less gear

 

That's my daily commute.
It's not just people from IL. I've been making that drive for almost 7 years, I know where they like to sit. If I were driving as fast as the FIBs at that point, they'd pull me over, too. I always slow down to about 70-75 when I get to the state line on my way home.

 

If you do the math, the ATs are going 86.4mph at 3500rpm, and the MTs are only going 75.4mph.

rpm/highest gear ratio/final drive ratio*PI*diameter in inches/12/5280*60=mph

Probably not the easiest way to get the speed for a given engine rpm, but that's what I came up with, and it seems correct.

 

I hate you...LOL
I'm lucky to get high 20's even if i shift below 3500. Of course, don't do any freeway driving, highest I go is about 65. My average is about 24.

 

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Well, now I've got the answer to my original question anyway...

When I left for my vacation, I unplugged MIVEC and drove almost exactly 300 miles on a full tank two times in a row (unfortunatlely, with heavy use of the A/C). It's not that bad IMO.

When we got back, I left the MIVEC on... and drove almost exactly 300 miles on a full thank (with generous use of the A/C).


Conclusion: don't bother turning it off for highway driving. And don't turn it off for city use either... the engine kinda chokes around 5000 RPM, which is quite unsettling when driving a car that you usually push to 4500 RPM in normal conditions. I often forgot about that when passing and shifted down to 4th for better power... only to have the engine choke on me.

Therefore, I think the only way to affect your mileage through any tweaking of the MIVEC would involve a custom controller for it... a product that would also let you had power to your engine at some other moments.

So let's all pray to the god of mods so that he sends gifts our way... Rob???

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the thing is....
our mivec as of today "cant be controled"
the only "way" and this just my opinion (not a tecnical advise) to "modify" is to make the oil flow faster and at a greater rate/ pressure so the triggers can engage "sooner"
i know is kind bs what i just wrote is just an hipotesis....

 

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Isn't the MIVEC activated/controlled by an electronics box? You seem to suggest it's kinda automatically engaged by the way of oil pressure flowing more rapidly as the engine revs up. But that can't be the case since I only had to unplug one of the connectors to stop it from engaging the more agressive setting...


BTW: Considering the fact that my fuel consumption didn't improve when I disconnected MIVEC... and also taking into account the fact that the engine kinda chokes around 5000 RPM when you unplug it, I wonder if the ECU is not supplying more fuel than needed to the engine? Can it be pumping fuel in at the same rate as it would be if the valves were fully oppenned? If so, it's no wonder it begins to choke at 5000 RPM... the fuel to air ratio is probably way off. I know the ECU should compensate for that when it gets out of range inputs from the sensors... but I wonder if it just wouldn't eventually hit the operationnal limits of it's program and then begin dumping to much fuel in the engine. Just thinking out loud here...

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^^ were dealing with a lot of factors but have not so many facts...
consensus is that is "oil pressure" activated...
lets hope someone come up with an answer....