What is i-VTEC?
i-VTEC is an operating mode in 2006+ Civic engines that reduces pumping losses during some low engine load conditions (like steady cruising). Reduced pumping losses improves fuel efficiency. There are other variations on i-VTEC, but this post only covers my experience with the R18 engine in the 2006+ Civic.
Technical Overview of Honda's new R18 i-VTEC Implementation
Honda Worldwide | New 1.8l i-VTEC Engine
Why should I care?
It can improve your fuel economy! Gas engines are notoriously inefficient. Ideally, you want the engine running at peak efficiency or not at all. One of the more advanced hypermiling techniques is to alternate between these two states. Also known as pulse and glide, this maximizes your fuel economy. i-VTEC essentially adds a second efficiency peak that you can use. If driving conditions limit use of traditional P&G, try Pp&G (Pulse, pulse, and Glide). The second pulse is a weaker pulse with i-VTEC engaged. It's probably not as efficient as P&G in most situations, but it can help minimize your impact on surrounding traffic since your speed won't vary as quickly with the weaker pulse.
When is it active?
How can I monitor it?
- The engine must be warm: 60C (140F) or higher
- Engine speed must be 1,000-3,500 rpm
- Low engine load such as is used in cruising conditions
uabcar has figured out a way to splice an LED into the car's wiring so that it lights up when i-VTEC is active.
uabcar's DIY on 8thcivic.com
Alternatively, you can monitor i-VTEC with a ScanGaugeII. Unfortunately, you have to compare two different gauges to figure out i-VTEC: LOD and any of TPS, MAP, or IGN. Each of TPS, MAP, and IGN makes a noticeable jump when i-VTEC engages and disengages. Watch the following video to see what I mean. Sorry for the poor quality.