I guess stock Maxima ECU has been 'jammed' in this 14.7 - in all closed loop circumstances. Maybe manipulating no-load cruising would be worth the money?

Comments on this article, pls:

"...won’t running leaner than standard mixtures at high loads kill the engine - or the exhaust? The answer is: not if you’re a normal road driver.

...unplug the oxy sensor(s) and then tune the complete load range to whatever mixtures you want.... fuel consumption improvements of 15 – 20 per cent are quite possible with little or no change in performance.

(In everyday driving, nearly all cars hold what’s called a stoichiometric air/fuel ratio, where close to 14.7 kilograms of air are mixed with each kilogram of fuel.)"

http://www.autospeed.com/cms/A_3022/article.html

 

that's kinda cool actually. it's not a static change in AFR as you'd get with dropping fuel pressure... rather it reverts to more powerful, richer mixtures that make the most power at WOT but goes lean at low throttle. amirite?

 

I guess so. I am listening here and want input from racing tuners = is the globbal warming warning "DANGER & Co = son, too lean!" ... an oil sheik lie? Or can I manipulate O2/MAF and cruise as suggested with 16, up to 20:1 ratio and not burn my pistons, CAT?

 

in extreme racing applications (300+BHP/liter) i have seen lean condition literally EXPLODE an engine. like a large part of the engine came flying out the hood......

 

Yes. Still that wouldnt matter on highway: biggest concern after being slammed in cell would be: how long still before u get the lawyers.

The question is fuel $avings, std commute and how lean is too lean? ... and is there too lean? Racing equations wont apply here as used power hovers at 10-20%, excess heat etc limitations nowhere to be seen. ...like the article claim was, go up to 20:1 w/o problems.

 

Leaning out the mixture too far raises combustion chamber temps which increases detonation.

 

The article cries for exact definition to that too vague expression. Like sellin TEMP and receivin torq...

 

you can NOT be exact with the definition.
what is to lean in denver is not to lean in chicago.
it will also vary by vehicle as combustion chamber designs vary and their point of detonation will as well.
14.7 is what they have decided is the best all around safe ratio for as you like to put it "blondies"

 

well his article has it where the less throttle you are using, the leaner it gets. so maybe (from 0% to 100%, by 5% increments):
.0%...5%...10%..15%.20%..25%.30%.35%..40%..45%..50 %.55%..60%..65%.70%..75%..80%.85%.90%..95%.100%
18.0_17.0_16.0_15.5_15.0_14.8_14.7_14.5_14.3_14.1_ 13.9_13.7_13.5_13.3_13.2_13.1_12.9_12.8_12.7_12.6_ 12.5

 

a 6 speed tranny

 

meh if i had a 2nd gen gearset in mine i'd be good to go. i just hate how it's like
1st.....................2nd................3rd.... ....4th.5th <--3rd gen 5spd
1st.....................2nd................3rd.... ......4th....5th <-2nd gen 5spd has 4th and 5th further out

 

50mph im holdin 2 grand rpm

 

and in 4th? it's not a whole lot different. 3-4 is OK on the 3rd gen tranny but 5th is too dang close to 4th that the clutch has to pick the rpm back UP because it fell faster than i could shift, if i shift w/o touching the gas pedal.

 

Pls note that low rpm is beyond the scope of this thread. Blondies of Denver are in...

If that article is true, and u can safely cruise leaner while using 20% less fuel, then we all are with the blondies pissed by oil sheiks. And they have bought off all racing fanatic blondies into their chorus: WARNING! ...is their sales $ong...

If and when 99% vehicles spend cruising with 20% more than they should, then this issue is a intl conspiracy: computers, sensors, can take care of blondies & Denver - but now they have been intentionally fixed to that 14.7 to keep oil lube flowin on all gvmts, big oil companies happy

We - you - are being robbed extra 20% - every day via this 14.7 hoax

 

I can see this discussion taking on a monstrous characteristic, but here's my take on it:

In general, engine designers will know the material temp bounds in order to guarantee structural integrity and material reliability/durability of the motor's components - in particular heads/blocks/pistons etc involved in the handling of high temp combustion gasses/products.

It will surely be their goal (given their abilities) to outperform any other design in order to give their own survival (as a company and a means of putting food on the table) the best chance in the world - as such I don't really think this conspiracy thing can be viewed as serious because there are simply too many variables, for a non-engineering involved person like us lot (certainly me), to make a completely informed judgment on that.

Example:

If I were to get involved with mixture tuning I would approach it using the methods one sees in the manual control (done by the pilot) of mixtures on smaller airplane engines - ie - One monitors the exhaust gas temp of the individual cylinders (ideally want them all the same but any IM will have imbalances due to design restrictions), while optimizing power, then start leaning it out till you have a misfiring/lumpy engine while at a fixed engine load and speed (worst cylinder found) and then tweak the mixture control to run slightly richer - this is where you then run while at a fixed engine load and speed to obtain max fuel efficiency and material parameter safe operating ranges - again only for that particular engine load and operating conditions.

I would thus say that without knowing quite a lot of design parameters of the materials present in the motor, a person is basically doing a crap-shoot mixture control modification if you run at anything other than the safe (ito extracting max power from any given amount of fuel while still looking after the integrity of the motor) around 14.5 stoichiometric ratio.

Sure you can be lucky and by experimentation arrive at a point where you can run at a particular load/rev/environment/fuel etc etc combination and possibly run 20:1 (or whatever) without any mechanical damage, but its going to be so time consuming and engine specific/driver/fuel/environment/etc specific that any gains to be had by running leaner (?) than 14.5, will quickly be negated before you even start tuning en-mass.

Certainly, I don't think that its even remotely possible to devise a suggested mod that will be safe to run "leaner" than about 14.5 on a particular motor, that will suit also any and all 3rd gen motors, locations and driving styles.

In the end you are governed by the around 30% efficiency (ito extracting max power out of any fuel present) of the Carnot cycle as seen in the typical fuel burning internal combustion engine and the fact that you need a certain amount of oxygen to burn all the supplied fuel in the cylinder - iow - if you want power from fuel you have to supply fuel

 

Survival for a designer means also globally indestructible = be within known safe boundaries -and- youre not fired b/c 'rules' were broken.

Fuel ratio can be turned leaner until engine doesnt work. The known negative possibly disastrous effects are excess heat and knock, emissions. When using only 10% of engine capacity, this possibly (read the article) isnt even a problem ---> totally opposite to race induced claims. These averse variables are all dependent on circumstances, can be detected, and ratio quickly adjusted accordingly. (This is why some big 700smtg BMW's can get 5L/100km.)

Oxides of Nitrogen – NOx: The emissions issue is ridiculous %%-driven cartwheel. To get NOx emissions down, its deemed "safe" to increase fuel consumption 20%. This means total weighted emission will go up - doesnt matter as long as fuel consumption is up (definitely greenpee oilmarket goal) plus the %%-numbers nicer

Leaving all blk helicopters behind: My maxima has been glued to this stupid globally safe 14.7, I want to tune my VGE to sip 20% less fuel on the ideal cruising conditions, then jump to 14.7 before anything funny happens. (First I must get Knock Sensor in duty for sure...)

1. What is the best way to achieve this?
2. What is the chea-pest way to achieve this?

 

Sorry cannot help with details because I have not done it yet and probably will not either because imo there is very little if anything to be gained for the forseen effort required.

.................. but if you must - then
1. Do what I suggested already ito monitoring EGTs per cylinder and create an individualized map of parameters for your particular motor.
2. Cheapest way? ...................... walk, or feed it water with the fuel (water injection)?

 

Think we need to questions why you would expect an improvement in economy by running lean, 'x' amount of fuel, requires 'y' amount of oxygen to fully burn. injecting less fuel will result in a full burn with left over oxygen, causing an increase in certain emissions, and an increase in combustion temperatures, but I am unaware of any reason to assume burning 'x' amount of fuel with excess air/oxygen will produce more power than 'x' amount of fuel with the correct amount of oxygen.
The amount of oxygen in normal air has been use to calculate a 14.7 value, but depending on several factors, that number may not be exactly right, which is why we have an O2 sensor, this sensors the actual amount of oxygen left in the exhaust, and adjusts the mixture to suit.

However, running rich will certainly reduce fuel efficiency as raw fuel is wasted.

 

Thats already known fact by everyone: Mabe u (?) didnt read the article ... so pls dont personify a tech issue. Pls yall ppl base all claims against that.

A. Less fuel used means less fuel used (too simple, eh?) B. Stupidly achieved too lean means engine damage. Lots of space between A---B. Exploring this space needs NON preprogrammed brains.

The Maximas O2 stupid sensor is tuned to 14.7:100. I guess theres only the stupid program following it, (or maybe ? a hidden lean data set.)

How to -question is still open for all.

 

what we really need is a wideband 02 and an ECU that can actually keep up. our ECU just can't respond fast enough at higher loads to be effective, to it reverts to a guesstimate mapping (aka open loop). but it can be custom-tuned by the home user with a solderer and an EEPROM burner. I know the MAF reads higher temperature as 'less' air than lower temperature air... but does it have the same intuitiveness for altitude? i've only been from 300ft to 3400ft, but i was driving my car gentle on purpose in the high altitude so i wasn't sure what the power was like up there.

 

One O2 question: what happens if the heater supply to O2 is disconnected. It cools, yes, but what is the effect?

------------------------------------------------------------

Any info on these products? Usable on VG & OBD-I?

http://202.43.230.118/

http://www.wbo2.com/

http://www.wbo2.com/2y/default.htm


http://www.innovatemotorsports.com/products/lc1.php

 

Correction there:

The ECU and injectors are more than able to respond fast enough to any change detected by the O2 - the actual problem is the O2 sensor itself as well as the time it takes for the effect of a newly calculated and injected fuel quantity getting burned under the current operating conditions to cause a stable signal to be generated on the O2 sensor in the cat - the engine components (cylinders/pistons/valves/plugs/exhaust manifold/exhaust tubing itself/ etc) all have a thermal/chemical delay affecting flow and gas characteristics that must be accounted for before the O2 sensor output is any indication of the real happenings inside the engine, and till that has happened any premature mixture change commanded because of an O2 signal may turn out to be totally counter productive.


The MAF's operation is a function of the amount of sensor cooling experienced by the unit when a fixed and calibrated known amount of heat is pumped into it - that amount of cooling is directly proportional to the mass of air moving passed/across the sensor per unit time - that mass is directly proportional to the air temp and density (hight above sea-level etc), so yes, the MAF is pretty knowledgeably when talking mass of air moving past it per unit time given just about any atmospheric condition found on earth.

 

so what we're getting at is that it's best to have a way to monitor what the car is doing, and drive it around enough to get reproducable results, then tune the ECU oneself and continue testing incremental changes until a good power/economy balance is found.

 

Indeed - and as said before, its going to be extremely motor specific ...................

 

as in MY tuning setup may not work for, say, Benstoked's engine?

actually i'm curious to know how my car would run with a South African non-O2-sensor ECU.... which is already tuned differently than mine would be.

anyhow what i was getting with the altitude and the MAF was that the same tuning would work for my engine, whether i'm in the mountains or on the beach, right? as long as it's specific to my car? i'm in the process of putting together a better motor than what i have now, with a 12.5ohms on all injectors but #1 (12.6) and #4 (12.4), and i will be testing compression soon just to verify uniformity. should run nicely once ECU gets tuned. (i have a spare ECU to play with as well)

thinking about it, i don't see any way for a leaner-than stoich ratio to save gas, EXCEPT that having the TB open more yields less losses from intake resistance. but I don't know just how big of a difference that would really make. but based on the principle of limiting factors, running leaner than stoich wouldn't increase fuel economy (it would increase emissions tho), but it would make the first 5% of the throttle much more lethargic to respond (taking 13% throttle to get 10% throttle's worth of power).. which may not be so bad on a m/t, because they can be kind of snappy on/off throttle. that's why in parking lots i try to stay under 1600rpm so the fuel won't cut off even at 0% throttle. but regardless, to make x amount of power you still need to use x amount of fuel...

 

As ECU does what it has been programmed to do, affecting inputs will change results, w/o 'expensive' ECU tuning. I see modding signals as the cheapest way... and driving the sensor signal mod = ON only via TCU lock ctrl signal or some other external sw.

Modding either O2 output -or- MAF with O2 cutoff.

(To give perspective, my EUgas is now about 8.5$ a gallon, = 90% is tax... This very cheap... This price is based on Euro/$ exchage rate, now about 1.55. This national socialist tax pendulum has been fixed so that IF some day dollar = euro, may become true, then politicigangsters will be mad hoppin of joy as price is maybe at 25$ per gallon. Greenpee goals accomplished In such a setting sipping gas will become meaningful or should I say prerequisite to survive.)

 

what's your definiton of "expensive" to mod an ECU? $10 too much? $50 too much? the person who first told me about EEPROM editing for the VG ECU indicated to me that it could be done for not-very-much money.

since our 02 is binary (on/off) you can't really use resistors and stuff to skew the feedback of that... changing the inputs would probably throw other things off too... really if you want to change something it's best to change only what you with to change, rather than changing an input that will cause weirdness across the board. but if you want, just unplug your 02 sensor and drop your fuel pressure a little bit and tell us how it runs and what MPG you get after that.

 

'1000$' programmable ECU is not cost effective in saving although it might be a must in racing.

I have prommer in a box, used last time 20yrs ago... however, peeking into a rom, every bit looks the same to me ...thus some info for my poor brains from jap-an-eses logik is a must. Where is that info available? Now that t_here is a spare ECU, could be done.

My guess is that via manipulating O2 heater voltage one can raise/lower the switch point. Never tried, just a guess.

 

http://eccs.hybridka.com/viewtopic.php?t=47

http://www.ecu2.forumwise.com/

 

My guess is that we have the same ECU program as you guys with the O2s, but only with the feedback loop disabled (air and fuel condition ranges must surely be the same allover the world so the initial ignition/fuel maps should be the same).

For you to see how your car will perform, you need to make your ECU work like ours - ie - remove the O2 feedback's influence - easiest is to measure the flip-flopping signal on a working O2 sensor (to find exact characteristics of the signal at 14.7), and on a 3rd gen motor in good condition/tune, then replace the O2 signal with a simple fixed square wave osscilator and you have an ECU that will effectively work in open loop mode off of the pre-programmed map.

.................... and once you have done that, you can tweak the MAF signal to make it read higher or lower (simple resistor to ground or 12V), thereby fooling the ECU into thinking its required to squirt more or less fuel to suit your leaner or richer endeavors.

 

wait tell me more about this square wave oscillator... what's it going to do as opposed to just unplugging the 02?

 

hey cape I know your all about the EEPROM, but for us VG30E drivers, the nistune would work very well for this. You could run a a wide band O2 sensor and have data logging and on the road tunning, or even a wide band and a SAFC or VAFC.

 

i'm not partucarly 'all about' anything... the EEPROM is just the one method i had heard of. I run a stock ECU and probably will for a while. I'm not going to mess with that sort of stuff right now... I'm still working on getting basic functionality. plus i might get some cams to put in it, so all the tuning i do on stock cams will be thrown out the window at that point anyways.

 

are you still running the auto ECU or did you get the "wingnut" ECU swapped in?

 

I'd get a JWT ecu or something but the fact that they are "optimized for premium fuel" or whatever according to their website makes me think I wouldn't be able to safely run regular unleaded and I don't believe in spending money on the maxima to make it waste more money on gas. If my tank worked like a breeder reactor I'd be saving $30 or so a week and putting in premium fuel would cost me at least another buck or two a week. Not to mention gas prices aren't going to stop rising.

 

no, the wingnut ECU is my spare at the moment, which i may reprogram or something. that dude rmdl51 is still battling his car last we heard, so he may need my known-good a/t ECU, at which point i'd just toss the wingnut one in straight away. but you'll be happy to know that i'm actually going to use wingnut's motor as my future DD motor. the tbelt'd car i just got last month has near-perfect injectors so they are going onto wingnut's motor, as well as freshly cleaned and painted mainfolds, new studs, new gaskets, vac hoses, basically a full non-rebuild restoration.

 

yes, they will likely keep rising, but if people spent HALF as much time finding ways to use less fuel as they did *****ing&moaning about the prices and blaming this and that person or company.... they'd at least have room to complain. yet they still drive 90mph down the left 2 lanes of the interstate so eff them. I followed a dude doing 60 in the middle lane of a 65mph zone and i was like "heh, whatever." prolly saved $0.75 riding those 10 miles 10mph slower than everyone else. .75x365 is something like 200 dollars.... what could you do with an extra $200?

 

Buy a Y pipe? Not sure after that but I mean still. I do use WOT more than I should for fuel economy but I'm known for slowing down traffic by taking my foot off the gas before when I'm expecting to use my brakes and I try to stay under 55 and draft as much as I can safely (I tell my girlfriend though, don't you dare drive as close to people as I do when you get your license). I consider myself to be fairly good at squeezing extra miles out of my tank. After all some people here claim to get less than 15 and I'm getting nearly 20mpg or so (can't be sure without some sort of measuring instruments and a scangauge only works on OBD-II so thats not a mod I can do simply)

 

just fill up the tank and push the trip meter back to 000.0 to get your mpg reading. divide miles driven by gallons refilled. 20mpg sucks really... i literally have not seen less than 24mpg in the past 4 months. check your codes... maybe o2 sensor.

 

Only sensor I have any suspicion of it not working is the dash coolant temperature sensor, which I need to remember to go to the autozone on the other side of town to get a replacement for. 24mpg is really good for a Maxima. I can't exactly do that since I have to pre-pay for gas so my tank rarely goes much more than 3/4s full.