Lean out AFR in closed loop

[Kenneth]

Well, it seems after some research that the ideal AFR for gasoline (max EGTs or in other words best efficiency) is actually ~15.2 to 15.3.

It seems that 14.7 is better for emmisions though, which is why it is used in cars.

So, if you can get your car to run at ~15.2 AFR then you will save gas without any loss of power. in fact your engine will run more efficiently.
Downside is that you may fail emissions testing (which we dont yet have in NZ)
This will apparently increase you NOx emmissions while decreasing CO.

Found details here: http://www.innovatemotorsports.com/f...hread.php?t=44

As the info in the forum link says, this will only affect CLOSED LOOP running, so as soon as you mash the gas pedal then you go open loop and back to standard AFRs.

Food for thought

[bradc]

After you sent me that link earlier on in the day, I was thinking about it, how much would a change from 14.7 to 15.2 actually make?

And also, do you know what our cars actually run at when they are running along at a steady speed? It is close to 14.7 or is it quite rich?

[Wodjno]

After you sent me that link earlier on in the day, I was thinking about it, how much would a change from 14.7 to 15.2 actually make?

And also, do you know what our cars actually run at when they are running along at a steady speed? It is close to 14.7 or is it quite rich?

It's close to 14.7 Mine was teetering between 14.5 and 14.7 at steady throttle while cruising.

[EdmundVR4]

Hey Wodjno, I presume you have a wideband that you are getting those readings from (14.5 - 14.7 afr), I get the same. What do you get at WOT...I get low 10's on mine without using fuel control. With my Field fuel controller I have it adjusted to 10.8 - 11.2 at WOT...I hope that is SAFE. What do you think ?

[Wodjno]

Hey Wodjno, I presume you have a wideband that you are getting those readings from (14.5 - 14.7 afr), I get the same. What do you get at WOT...I get low 10's on mine without using fuel control. With my Field fuel controller I have it adjusted to 10.8 - 11.2 at WOT...I hope that is SAFE. What do you think ?

See here .. http://www.clubvr4.com/forum/showthr...highlight=lm-1
Post 7

[EdmundVR4]

Thanks Wodjno, I missed that "thread".
The best fuel here is supposedly 95RON & I am using water injection to ward off detonation...so I may lean it out a bit more.

[bradc]

somewhere around 12 seems to be the favourite AFR for most people at full throttle. my car runs at about 11.0-11.4 at the top end of the rev range.

[B16REE]

0.88 - 0.90 lamda is for power i think in AFR its about 12.8 - 13.2

[bradc]

Thats a little too lean for a turbo though isn't it?

[Wodjno]

0.88 - 0.90 lamda is for power i think in AFR its about 12.8 - 13.2

Thats a little too lean for a turbo though isn't it?

Yes Mr Radc, 0.88-0.90 is to lean for a Turbo'd car !!

I have mine at 11.7-12.0/ 0.80 - 0.827 at WOT..


Some choose to go alittle richer than this 0.77-0.79 lambda / 11.2 - 11.5 AFR

Each to there own and all that.. But 0.88-0.90 lamda is deffo to lean for our cars

[bradc]

I'm happy to stick with 12.0-12.5 at the top end, the Autronic should let me run little leaner than normal and it can still keep the timing and stuff in check as well.

[Wodjno]

Whats you AFR's like while Boost is building up Brad ??

How quick do the AFR's drop ??

[Eurospec]

Ree runs a NA guys, but yeah its too lean for a turbo car.

Question though, unless you have some sort of ability to intercept the O2 signal, or aftermarket electronics, wont using a normal fuel controller to lean out the cruise just result in the std ecu moving the fuel trims to richen it back up?

Cheers,

Ben.

[Wodjno]

Ree runs a NA guys, but yeah its too lean for a turbo car.

Question though, unless you have some sort of ability to intercept the O2 signal, or aftermarket electronics, wont using a normal fuel controller to lean out the cruise just result in the std ecu moving the fuel trims to richen it back up?

Cheers,

Ben.

What is being done by the LC-1 is it is making the ECU think that it is still seeing 14.7 AFR, so it won't adjust it..

I have tuned my car via Emanage Ultimate to lean out the AFR to around 15.2 via an air fuel map.. But it seems to be fighting against the standard ECU, so it's a bit skittish ! Meaning that it doesn't always go to 15.2 when cruising, it stays at 14.7. But after a while it stabilises at 15.2.. Not sure why it does this.. But as i said, it seems as though 1 ECU is fighting the other !
But leaning it out vis the LC-1 by altering the voltage, seems to be the best way to achieve it..

[bradc]

Removing the stock ecu entirely is the best way to go

Wodjno, my car isn't properly tuned yet, I'll keep you in the know however.