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Hi all,

Like most of the new members here I've been poking around for some time. I started out trying to get more mileage out of my '03 4x4 Ranger with the 4.0l engine. I bought an SGII and that took me from 17.5 to 19.5 with the help of this and other web sites. Not good enough. Not convinced with the benefit of all the technology in the hybrids I started looking for a Civic VX, HX or CX and ended up with a '98 HX w/57k miles. Now it's time to get serious.

The VX/HX Civics seem to have a lot of uniquenesses, although not as many as a hybrid, that are not well understood. When the VTEC kicks this is straight forward, when lean-burn kicks in this is somewhat less clear. I know members 99HXCivic and VTEC-E are Civic lean-burn guys, hopefully I can learn much.

Regards,
Dennis

Welcome, Dennis! How long have you had the car? Is it a manual or automatic transmission vehicle? What sort of terrain, traffic, and temperatures do you normally travel in?

Right Lane Cruiser,

I've owned the car for just under a month although I've only had it on the road the past two weeks. With the car being almost ten years old, although only 57k, I changed out all the fluids, new muffler, new spark plugs, adjusted the valve clearance, etc. Basically all the maintenance items. It is a manual, the CVT was not an option in my mind. I'm in South East Michigan so the terrian is fairly level, kind of out in the country so traffic is not too heavy and we have four full seasons. My first tank I pulled 42 MPG while still learning the car, I'm thinking I could get into the upper 40s eventually.

I'm thinking I could get into the upper 40s eventually.

Shoot for 50 and keep us posted on your progress.

With lean burn you should be able to get into the 50s pretty easily. I would think you could hit the 60s if you throw the book at it. Especially if you do a lot of highway driving.

I'm on the edge of breaking into 50s in a del sol si, doing almost exclusively stop and go driving. So that should give you and idea of what is possible.

You have a lot of stuff going for you with that car. With some effort you should be able to get well beyond the numbers that i'm capable of.

Excellent to hear! Koreberg is right -- you have a great car and it sounds as though you have ideal terrain and traffic to work with as well!

Because of lean burn the SG won't be able to determine your fuel economy correctly but one thing you can do to help insure you are in a good lean burn zone is to accelerate gently and when up to speed, back off the pedal ever so lightly while maintaining speed. You want to find that minimum pressure on the gas pedal that will keep you at speed. Drive with load over any slopes and keep your speeds down. 55mph should be very good mileage-wise, and 60mph won't be too bad either.

I still think the SG is useful in your case -- just know that when the car is using lean burn it could be as much as 30% more efficient than what the SG shows. You can still use load, TPS, water temp, and 12V status when driving to help you maximize your results. :)

You'll want to throw FASing into the mix whenever you can -- that's where monitoring the 12V status is important. I'd also be REALLY interested in finding out what a vehicle that won't drop out of lean burn until you hit it REALLY hard can do with P&G! I can't push the Insight in lean burn because it promptly falls out of it...

Sean,

I started monitoring the O2 sensors with the SG to identify lean burn. It appears bank 1, sensor 2 is the wide band sensor. Cold it reads 127, once warmed up it varies wildly under 100 with the throttle, when the throttle evens out there is a reading between 5 and 9, then when it drops to 1 then 0 and there is a noticable lack of acceleration. This appears to be what I will call full lean burn. When it "pops" out of 1/0 there is a noticable surge. This is getting to a question... It seems like to get into "full leam burn" there is a specific RPM range, between 2300 and 2600 RPMs. Do the lower O2 reading indicate partial lean burn with partial MPG gains or is it all or nothing?

Dennis

I don't really have enough knowledge about this to answer you completely (Ben??) but I can tell you that at least with the Insight and the HCH-I 5spd there is a range for lean-burn and it isn't limited to the range of RPMs you've listed. I'm often cruising in my Insight at not much over 1k RPM in 5th and between 125 and 150mpg at 35mph or so. There is an upper limit on the Insight lean burn -- it will drop out when you get to mid or upper 50s without a tailwind. I believe I've seen somewhere here that your car will stay in lean burn up to about 70mph or so.

I'm not really sure what to make of your O2 sensor data... (Ben?? Thoughts?)

Its a completly different engine, but the d15b vtec supposedly does lean burn from around 0-3k according to this guy.
http://asia.vtec.net/article/d15b/

I would imagine that the other lean burn vtec engines are similar.

As for the other stuff I really don't know enough about scan gauage or vtec-e engines to say tell you anything useful.