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Marc F. 06-02-2012 09:46 AM

i-VTEC hypermiling

If you have an 1.8 liter i-VTEC engine, like in a 2006 to 2011 Honda Civic, this is the thread for information on hypermiling. Questions and answers go here. This may apply to other Honda engines too, but, VTEC can be used in many different ways.

***EDIT*** If you have a different VTEC stay here! Just specify year/type/no. of cylinders etc. to help people know which system we are talking about.*******

The i-VTEC is a little different from your other VTEC engines. In a nutshell it has Eco cams that activate from 1000 to 3500 rpms when the conditions are right.

BUT WAIT THERES MORE!!! It changes to a unqiue cycle where the butterfly is wide open and the closing of the intake valves now controls the the throttling of the engine. This change is why Honda went with Drive By Wire (DBW). The butterfly needs to flick open almost instantly.

Why the weird cycle? To reduce pumping losses of the engine pulling a vacuum against the butterfly. This engine has other friction reducing features.

To help maximize your mileage keep it in eco mode, I personally started with a light to know when i-VTEC is on, here is a link to that process and a few other links to get you started:

i-vtec solenoid wiring help - 8th Generation Honda Civic Forum

2006 Honda Civic 1.8 SOHC i-VTEC engine

Also a good visual on basic VTEC:

Honda Worldwide | Technology Picture Book | i-VTEC

The thread that started this one.

Original thread

Marc F. 06-02-2012 09:55 AM

i-VTEC Light install warning,

When reading up on this and knowing a little about how eletricity works I noticed a mistake by one guy. He got an 12 volt LED and spliced it to both sides of the solenoid and got a Check Engine Light (CEL).

Splice only one side of the solenoid (black wire with a white stripe for mine) and ground the other side of the LED. Otherwise electricity tries to take the path of least resisitance, which is the LED, and the solenoid wont do its thing. CEL!

I got my 12 LED at Radio Shack and it works great. It came with red and black leads to make wiring easier.

Its not hard to do this modification, just take your time and think things through.

Marc F. 06-03-2012 01:59 PM

Does anybody have a Scangauge on a R18 in a Civic? How easy was it to set up?

The light has helped in my quest for better mileage but to understand and drive this engine to its full potential I figure a Scangauge is the cats meow.

In less than 2 weeks my daughter gets married and after that I will be looking seriously at buying one. Till then I just need info.

Marc F. 06-10-2012 10:25 AM

Ok, so it takes a very light pedal to keep it in eco mode. The other day it was very humid and I had a heck of a time getting it into and keeping it in eco mode.

Any ideas on why this is? Does humidity factor into the air-fuel ratio on honda engines? That is the only thing I could figure, it was messing with a sensor. If somebody knows the knowledge would be great. :)

If so, then that begs the question, are mpg figures in some areas, due to humid/dry conditions, lower/higher?

ksa8907 06-10-2012 10:55 AM

humidity will lower power output, forcing you to press the throttle more for the same power. yes, humidity will affect mileage. ever wonder why drag racers care so much about the temperature, pressure, and humidity? mid 70's with high pressure and low humidity means fast times.

Marc F. 06-10-2012 02:41 PM

I seem to remember that but I wanted to be sure. I never tuned a car to that level, keeping records of barometric pressure, humidity, etc.

The cycle a R18 goes in to for eco mode is low power so it makes sense to stay in normal mode when the humidy is high.

So I wonder if it is a specific sensor for humidity? I guess I will start looking around for info.

Maybe its a way to keep it in eco mode more of the time?

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