Honda hx lean burn
 

So, I have installed a D16Y5 into my hatch, and have decided to share some information and some background about the bulid.

D16Y5- a 1.6L V-tecE engine find in 1996-2000 honda civic coupe HX model.
I have completly rebuild it with new piston, new rings, new valves and had the long block trough the machine shop. everything is put together to factory spec. All equipments are connected including AC.

1996 Honda Civic Hatch DX, no power option, wieght-in at 2200 +/-.

There is no after market part installed.

Ultra gauge is use to monitor all the data.

Lean Burn data is as followed for my car

On 5th gear @2500-2700rpm, 63-67mph, 40-43 engine load, O2 bank 2 will hit 0000, while back one would be in.0.4+/-0.10 on the ultra gauge (thank you darcane for the tip). After I get into NB, I can drive +/- 5mph as long as i keep engine load below 90%, without any quick throttle changes, I can stay in LB. I can get between 48-63mpg while in lean burn if its on a flat. 65 was my best but thats only if its flat and it only lasted for maybe a mile.

on 4th gear, I am not very good at getting in LB yet, but its about 2200-2500rpm @40mpg, same load, and O2 bank 2 will also hit 0000/LB. and the i can get around 44-55mpg accounding to the gauge.

1,2,3 does not offer LB mode so, I try to get out of them as quickly as i could without passing 2500 rpm and use the V-tecE feature and keep 4 valves partly open.

more info to be follow as I am still trying to understand and learn how to drive this car!!:thumbup:

note: I have asked this question about what LB feels like to other HX drivers, however, i do not feel any different beteeen transition from LB to normal drives, It was petty smoth except the IMPG would chnage to "off the chart" mpg once in LB!

For a test try to enter 4th gear lean burn at the 2500 - 2600 rpm mark.

If the car is all warmed up and been on for a mile or two, I seem to get in 100% of the time in 3rd, 4th, or 5th gear at 2500 - 2600 rpm. TPS 19% or less and LOD at 65 or less. Never fails.

When the car is in the proper "mood" I can get into a lowe RPM lean burn down to 1900 rpm. Once in I can remain in as long as don't:

1. drop below 1800-1900 rpm
2. make sudden changes
3. increase load or tps byond lean burn limits.

I never was able to stay in lowe rpm lean burn without using MMO though.

Cool!
Welcome to the HX world!

turborvr1991 mentioned MMO.
Marvel Mystery Oil, from car parts stores.
Bottle recommends 4 ounces per 10 gallons gas.
I use 2 ounces per 10 gallons gas.
Might need 2-3 tanks to get the full benefit.

I figured that with your fully rebuilt engine it would do lean burn down to 1800 rpm without any MMO. So my new interpretation is that the need for MMO is not because the engine is dirty - yours is CLEAN!! My guess now is that the cars were built for more standard gasoline without the alcohol and other junk included these days. Just maybe the MMO compensates for that change.

Regardless of why it works, several of us have found that it does. Try it in 2-3 tanks and see how things go for you.

And good luck!!

I am on the second tank of MMO already, not sure if its helping or not since I have just installed the ultragauge and the numbers are all new to me. I have every intension to not use MMO for a tank in the near future to see if it makes a different. I am still getting use to the driving style since I normally drives an Audi and an Evo and i have never attempt for mpg. This is all new to me and its kind of fun!!! Will update you guys on a weekly since that's how long a tank last!

Can someone refresh me on the Lb limits again??? TPS, load limits, RPM limits, thank you very much...

Nice details and specs... oddly my 1.8L corolla gets close to the same figures, but a lot less rpm at the given speeds and mine is an auto. I can't get anywhere them numbers for your 5th gear specs, but I get about the same for your 4th gear specs (mine is 45-55mpg @ 45mph)

The noticeable limits to enter lean burn seem to be:

1. warm engine driven for a mile or two at higher speeds. If I EOC, it takes a mile or two to get back into lean burn.

2. TPS (throttle position sensor) to be 19% or less.

3. LOD (engine load) to be 65 or less

4. RPM (I saved this one for last as I see two different RPM limits. AKA good mood, and bad mood.

I will start the "bad mood" lean burn. If the above conditions are met and I am at 2500 rpm, I will go into lean burn 100% of the time.

Good mood RPM limits engage around 1900-2000 rpm and can stay in anyware from 1800 - 3100 rpm. I can get into this when I first get on the highway and the engine first hits optimal temp. Once in I am able to stay in for 200+ miles If I fall out from hitting a traffic jam, it is hit or miss if I can get back in. Normally I am not able to get back in this good mood RPM lean burn.

The noticeable limits to stay in lean burn seem to be:

1. Steady throttle. try not to make any sudden changes

2. TPS (throttle position sensor) to be 12% to 30%. Go to low and it enters DFCO, go to high and it will kick out.

3. LOD (engine load) to be 90 or less

4. RPM Bad mood - 2400 - 3100
RPM Good mood - 1800 - 3100

I am still thinking it is something else. If it was a gas issue I would expect the VX to have the same problems on the newer fuel. I am half tempted to bite the bullet and get some pure gasoline from a marina to test this though.

Another thought is a clogged / high mileage catalytic converter. Has any HX owner replaced their Catalytic converter with a Dorman or OEM style? I know mine is still the 230k original HX exhaust manifold and catalytic converter.

I also ordered the OEM EGR valve to see if that makes a difference, but I really don't think it will have much of an effect. Will keep everyone posted though.

after a whole week of messing around with lean burn. I have figured out that with my car, I can get into lean burn at 2700rpm, with tps @ >15%, and load @ > 50. after entering, as long as I can maintain between 2000-3100 and the same throttle and less than 90% load, I can stay in. But the more interesting discovery I mad is that just because I am in LB, does not mean I am in the best gas saving mod. For example I found that on the highway, it is better to stay below 2500rpm about 60-62 mph in light traffic and take advantage of the Vtec-e, I can get anywhere between 48-63 on the IMPG but if i try to stay in LB, I would bounds between 20-60... this is only my third tank of gas on the new engine and new set up. I will keep updating until I figure things out weekly...

Hold on here. The one caveat with the Ultragauge (and Scan Gauge) is that it won't accurately report fuel economy in Lean Burn mode. I believe these gauges base mpgs off air flow, not fuel flow, so they are way off when it runs lean.

This is my thread trying to figure out how far off it is:
http://ecomodder.com/forum/showthrea...mpg-23441.html