Mods that help gas mileage?
Former G35driver Vendor
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Joined: Jul 2004
Posts: 3,054
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From: Los Angeles California
CKwik,
That's true, Ve changes should have little affect on A/F ratio, but it seems the VQ has a way of running leaner as VE mods are piled on.
I have often wondered about this and as you said the ECU is monitoring A/F in a closed loop mode via the O2 sensor and MAF with the goal of keeping a constant A/F for a given RPM/load.
But still it seems the engine runs leaner with the VE mods. It may be that the ECU balances a compromise between the factory presets and what the MAF/O2 sensors are calling for.
In the case of the Stillen CAI, I wouldn't call that a VE mod at all. The stock air box already flows too good to make a tangible improvement on. Pressure test's support this. I would say the Stillen CAI is more analogous to a MAF claibration tweaker.
and I'm always skeptical of Stillens claims.
I've never come across a specific reason to be skeptical of what they say but I guess I'm just a skeptic.
That's true, Ve changes should have little affect on A/F ratio, but it seems the VQ has a way of running leaner as VE mods are piled on.
I have often wondered about this and as you said the ECU is monitoring A/F in a closed loop mode via the O2 sensor and MAF with the goal of keeping a constant A/F for a given RPM/load.
But still it seems the engine runs leaner with the VE mods. It may be that the ECU balances a compromise between the factory presets and what the MAF/O2 sensors are calling for.
In the case of the Stillen CAI, I wouldn't call that a VE mod at all. The stock air box already flows too good to make a tangible improvement on. Pressure test's support this. I would say the Stillen CAI is more analogous to a MAF claibration tweaker.
and I'm always skeptical of Stillens claims. I've never come across a specific reason to be skeptical of what they say but I guess I'm just a skeptic.
Last edited by Hydrazine; Dec 20, 2004 at 02:35 PM.
Registered User
Joined: Dec 2003
Posts: 2,514
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From: Marietta, Georgia
The cruise mpg is set by the front O2 sensor/ecu ability to maintain a 14.7AF ratio during non acceleration.
Ethanolized gasoline fools the ecu into running richer [decreased mpg] due to the oxygenate [patial preburned thus the O in formula] in the gasoline.........about a 3-5% decrease. Try to avoid this fuel if you can. Under acceleration the lower BTU content also requires more fuel for the same power so even acceleration mpg suffers by 3-5%.
Ethanolized gasoline fools the ecu into running richer [decreased mpg] due to the oxygenate [patial preburned thus the O in formula] in the gasoline.........about a 3-5% decrease. Try to avoid this fuel if you can. Under acceleration the lower BTU content also requires more fuel for the same power so even acceleration mpg suffers by 3-5%.
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