Lets start by pointing the obvious im fairly new to the tuning stuff, but as the title states I wonder if it is possible to replicate in some ways the fuel map and ignition of the Civic Vx on lean burn. I did a lot of research on here but did not come across anything like that, I currently have some extra b18 laying around and after im done with the current build id like to experiment so any input would be appreciated at this point. I understand that the civic vx had a taller tranny also so I dont expect to reach close to the same mpg with a b18 but anything better would be interesting.

 

It could be done on the high end with a chip, but I think the ecu would attempt to stabilize at 14.7:1 at low/stable throttle positions. I'm new too, and look forward to a helpful answer.

 

The s200 obd1 ecu I picked up should have that cover and I started to learn to use romeditor4. If anyone wanna recommend some link or book for tuning id sure appreciate the info.

 

There are some threads on it here. Just search stuff like "mpg tune".

Im not a tuner, but, from what ive read it's fairly simple. Go for a highway drive while using a laptop to datalog. Find out which cells you are in during highway cruising. Then you lean the fuel mixture, and advance the ignition timing in those cells. You need a wideband to monitor your air/fuel ratio.

All in all it seems pretty simple. And dont worry to much about doing harm to your motor by running it too lean for a bit while tuning. At cruise there is not enough heat or pressure in the cylinder to do any real damage. Just make sure your final tune doesnt cause any knock or excessively lean conditions.

 

its simple to get close to that but you need to understand how the whole engine works

it has a wideband-to monitor afr changes very closely and adjust while in lean burn
it has EGR valve also to help in lean burn mode by providing a mix of exhaust gas into intake which lowers the exhaust temps in return and prevents detonation

but lean burn raises emissions so its banned in cali

you can just try to locate california ecu and theres also a bin file fro crome from california legal d15z1 i used it on mine with crome chip and it was ok but nothing special. no lean burn= no gas mileage

 

I believe the EGR is for emissions only, not mpg or performance in anyway.

 

It seems EGR helps mpg by reducing pumping loss. This is the closest thing to lean burn.

 

According to what I came across it did have an impact on it but I thought its main functions was to reduce NOX, but I might have overlooked actual mpg gain there. That being said since the b series dont have egr and I was thinking more on the tuning side perspective since I dont want to add an egr valve, hate it enough on the sbc that I got rid of it. Since I still have a lot of learning to do on tuning I just wanted to know if its feasible to trigger a different fuel & ignition map like I assume the vx ecu does.

 

Reducing the NOx is a side effect of lowering the exhaust temps, which is what recirculation of the exhaust gas helps achieve. If you do some reading on the chemistry of the burn the relationship is pretty clear. High exhaust temps also destroy catalyst.

There is more to the VX system than is immediately obvious, the D15Z used stratified charge (a carryover from the old CVCC engines of the 70's-80's) to help it run acceptably at those super lean AFRs. Basically, the vtec-E systems barely crack open one of the intake vales in the "low cam" mode to prevent puddling in that port and impart swirl in the combustion chamber. Engagement of the vtec solenoid simply opened that valve fully. It also intermittently shut the lean burn off to lower the catalyst temps. Bottom line, you're not going to get a B18 to run for poop at 20:1 AFR.

BE careful with running lean in general, exhaust temps are at their highest in the neighborhood of 16:1, but if you get too much higher you start running into lean misfire and torque starts to drop off fast. If you're not making torque, you'll use more throttle to maintain a given speed, and the whole thing is a wash.

Also, lean mixtures require more timing to burn effectively due to the lowered charge density, so you'll need to be aware of that. Just leaning out the mixture won't get you too far on its own. Since the the charge is less dense, the flame front literally takes longer to jump from molecule to molecule.

Lastly, all of this really needs to be done on a load-bearing dyno so that you can have some numbers to work with. You will want to have hard numbers for your knock limits and torque numbers at your breakpoints. Really hard to achieve on the road and basically not possible on an inertial dyno (I'm still not sure why these are still so common, aside from maybe the fact that they are cheaper).

That being said, you can see minor improvements by leaning out your cruise region a little, say to around 15.2-15.5:1, depending on your setup. I like to do it using the cruise on a stretch of really flat road on a nice calm day, and I watch the MAP & TPS numbers to get an idea if my torque is falling off. Add a little bit of timing and see if that helps too. You need to be listening for knock while you do this.

Doing this, along with installing some 370cc Bosch EV14 injectors (your stock b-series injectors are 80's tech and should go in the trash!) has allowed me to get my B20Z/GSR trans 00 sedan to get about 34mpg on the highway and about 22-23mpg around town. Not too shabby for a thirsty non-vtec 2.0L with a short geared trans.

Lean burn has been illegal everywhere in the United States since the early 2000's due to NOx emissions, hence why the first gen insight was sooooo good on the highway (80mpg+ was achiveable!) but modern hybrids aren't. Some countries still have it, Australia comes to mind. I've heard you can swap and Australian spec (ADM? ) ecu into the Holden-based USDM GM cars and you will get lean burn, and as such, better mpg. Total rumor though.

It's really a shame, I feel that there should be more to the equation than just what comes out of the tail pipe. Better mpg means less fuel consumed means less can be produced, stored, shipped, etc., which ultimately means less emissions overall. I feel it's a "missing the forest for the trees" kind of situation.

 

I meant when the z1 first was introduced.

what im wondering is.

does z1 really produce that much more emissions than a single cam with 35 mpg?


if calculated emissions per mile

 

Overall? Probably not. It sure isn't spewing huge HC numbers.

That was kind of the point of my comment. I feel that the lack of lean burn capability shows a shortsightedness in the way the regulations are laid out. Then again, I live in a state with no tailpipe regulations per se, so I've never actually even seen a five gas analyzer. Since they don't really apply to me, I'm not 100% familiar with how the laws are written.

 

But I guess my curiosity is more in the fuel map and ignition in this case, I understand your point of view and I really enjoy getting to know more on anything but maybe there is more to its potential then actually known. Also using forged internal could help withstand more heat then the stock cast setup. I know the vx need certain criteria to engage lean burn I wonder if it is replicable, I am not trying to say here I want learn burn at all time but as mentioned before I have 2 extra running b18a and Im starting to learn to tune so it wouldnt hurt me so much if I blew one doing some trial. English isnt my first language btw if my english sound weird.

 

the egr and wideband are there for a reason. you cant just wish for it like u in wonderland and expect it to work magically without required components.
prelude has egr system, gsr has egr port thats not machined and could be added and you can control it through neptune or hondata

if you really want to make a lean burn b series and spend alot of time when the prelude is very close to b series

 

Dude thanks for your input but I think you dont get my point here, I am in the tuning section for a reason, im not trying to reinvent the wheel here just trying to find out how the lean burn is trigger in the vx ecu and see if theres way to replicate it in the b. No need to get defensive if I dont agree with the egr crap and yes I was aware of the wideband, but there always other way to address temp, possibly water/methanol spray but im still in the studying stage since Im working on building 2 engine at the moment.

 

If you know what egr does then u would understand how the whole system works

Its triggered only at cruising speed during low load
All other times its just plain old 14.7

 

Theres other way if you read the article

And it goes further than egr and wideband

Its intake manifold design the combustion chamber design throttle body and intake diameter
Etc its all designed for that engine

 

The problem is, 'lean burn' is not just a computer tune. The engine itself was designed to burn fuel efficiently at super lean A/F ratios. The B18 does not have that design. If you go too lean, you will damage the engine.

Like has been said before, you CAN lean it out a bit (mid 15 A/F) and advance the ignition to help it burn, but thats about it.

 

I understand your trying to make sure I dont do something stupid and blow the engine but as previously stated I dont care if it does (using spare engine with high mileage). My point is there is more then one way to address an issue, Im sure the discussion were the same when then Lsvtec first came to light. I do know how the EGR work and I do understand the engine is differently designed but I dont mind doing some trial and error, I also know for a fact that nox and temp decrease when you aggressively lean the mixture and change timing more. I might not sound like I know alot since I try to not sound cocky, frenchy tend to sound like it alot hehe, but my point is they were able to build 6 stroke engine and inject water to cool the pistons and delete the radiator in early engine design so I see potential where other people may not. Again im not saying its feasible but to me its worth a trying even if I blow it.

 

You are missing the main point here.

The "lean burn" system is not just a super lean fuel tune. It is an entire system working together to use less fuel. Its not the EGR that increases the mileage, its not the tune that increases the mileage, its not the pistons, its not the combustion chamber, its not the cams, etc, etc. It is the combination of all of those things that add up to the incredible mileage that the system achieves. Without every one of those components, the system would not be as efficient.

Once again, you cannot just throw a "lean burn" tune onto an otherwise ordinary engine and expect and crazy gains. You will see a couple MPG, sure, but really nothing to write home about.

 

Lol nhaa im not missing anything, I guess im not expressing myself to well but either way ill follow up with what happened when time come, dont worry im not expecting the vx tall gear light shell mpg in a da9 with shortgear. Either way im stubborn and more interested in tune information if anyone wanna talk about that instead of anything egr related.

 

Nothing I personally said has been EGR related.

Tune related: You cant go any leaner than mid 15:1 on a stock B18 motor. And that will not yield very much MPG increase over the standard 14.7

 

As I mentioned before water/meth might help lean it even more. I remember the chart showing how at a certain point when you lean it pass like 30:1 the temp and nox start going down again. I know they wont be most likely enough power left but I dont mind trying some real test instead of just theory.

 

The engine will not support 30:1 AFR. It just wont work. Even if you get it to burn, there will not be enough energy (in the form of gas) to propel the car forward...

 

well it seems like you got enough info to try so i think this is resolved

 

Lol obviously, I guess Ill stop stirring the pot here if anyone wanna suggest me some tuning book I just ordered "Engine Management: Advance Tuning". But im still interested on finding how the ecu trigger the map even if its not replicable but thanks for not flaming me hard.