Good Lambda/AFR for Diesel

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Good Lambda/AFR for Diesel

Postby rlees85 » Wed Sep 26, 2012 6:08 pm

As you can see here, ecuedit ripped into my tune :oops: http://www.ecuedit.com/post2170#p2169

First thing I need to get straight is the smoke map, in my opinion, as boost maps/torque limiters depend on this abit. This defines how much fuel I can run given an amount of air.

My research has led me to some confusing answers.

Stoichometric for Diesel is 14.5

I have read on many places online that running a Diesel bang-on Stoich will make it smoke. I also have a tuned file for a Peugeot 306 where the smoke map hangs around 13.5-14.5 AFR and that smoked. Funnily, this map was done by a tuner with a good reputation (i mean by the online community, not a tuning company), so not sure what his reasons are for this.

I also read online on a few websites that aiming for 17.5 AFR is ok for low revs up to 18/19 for high revs... so I made my smoke map around this but ecuedit says the lambda is too high (AFR too much air), which makes it clear why I had such a hard time trying to supply enough air in my turbo maps.

So my question is, is there an AFR that we should work too? Or is it better to take a good guess (say 15 (14.5 lowest!) low revs and 16 at high revs) and then test, if smokey, increase more?

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Re: Good Lambda/AFR for Diesel

Postby Relic » Wed Sep 26, 2012 9:29 pm

We learn from mistakes....its a good thing to make them before we get cocky.
From my limited experience..... :shifty:

I have logged and studied some tuned maps on mine by reputable tuners as well as the oem.
The tuned maps run no more than 17:1.
22:1 - 18:1 is considered smoke free.
Some people are of the opinion 18:1 is ultimately the best.
OEM runs 19.6:1 : high rpm

BUT at low revs on mine at least the lambda is set much richer than this.
lambda 0.93 @ 600-1000rpm
I cant say if yours or all other diesel can run so much richer at low rpm.
Have a real good look at the stock maps and stick to this at low rpm.
IMO

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Re: Good Lambda/AFR for Diesel

Postby ecuedit » Thu Sep 27, 2012 8:44 am

rlees85, you are on the very good way to do it right. That takes some time. But when you do it by yourself you will know a lot ;)

About comparing lambda to other tunes...newer do that you will always get mislead, why? Because -->

You maybe really checked the lambda in other tune and you got information that there is smoke.
Everything that can be true, but 99,99% of guys who make modifications increase injection duration to get more fuel into the cylinders...that's wrong way.

They do that because they do not know how to find all limiters, maps, how to make calculations, axis extends, cross checks, dependencies, physics, mathematics, mechanical knowledge and so on...that's a lot of work, and good tune can be done only hard way.

Because of that ECU can not calculate how much fuel it gets and if you have limiter in smoke map in some circumstances IQ85,
and lambda 15 your car smokes because you are actually getting more fuel into the cylinders (decalibrated injection duration map) than IQ85 because you inject a lot more time...

I post a picture in previous post and there you can se lambda you can drive:

lower lambda - more power, worse consumption (here you go far until it starts to smoke...than you go step backwards)
higher lambda - less power, better consumption

Think out of the box do not get limited by other tunes,
very fast you will realise (i believe faster than in two months) that out there is bunch of tuners that think they are tuners :)

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Re: Good Lambda/AFR for Diesel

Postby ross2482 » Thu Sep 27, 2012 1:53 pm

In my tune file that I'm currently developing, I've aimed for about 17.4 AFR in the smokemaps. I've yet to test this, but will hopefully do so soon and will see if there is any smoke! :)

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Re: Good Lambda/AFR for Diesel

Postby ecuedit » Thu Sep 27, 2012 2:12 pm

AFR based on mm3 or mg...there is difference...

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Re: Good Lambda/AFR for Diesel

Postby Relic » Thu Sep 27, 2012 2:20 pm

ecuedit wrote:rlees85,
About comparing lambda to other tunes...newer do that you will always get mislead, why? Because -->

You maybe really checked the lambda in other tune and you got information that there is smoke.
Everything that can be true, but 99,99% of guys who make modifications increase injection duration to get more fuel into the cylinders...that's wrong way.

They do that because they do not know how to find all limiters, maps, how to make calculations, axis extends, cross checks, dependencies, physics, mathematics, mechanical knowledge and so on...that's a lot of work, and good tune can be done only hard way.

Because of that ECU can not calculate how much fuel it gets and if you have limiter in smoke map in some circumstances IQ85,
and lambda 15 your car smokes because you are actually getting more fuel into the cylinders (decalibrated injection duration map) than IQ85 because you inject a lot more time...

I post a picture in previous post and there you can se lambda you can drive:

lower lambda - more power, worse consumption (here you go far until it starts to smoke...than you go step backwards)
higher lambda - less power, better consumption

Think out of the box do not get limited by other tunes,
very fast you will realise (i believe faster than in two months) that out there is bunch of tuners that think they are tuners :)


I agree with you lambda tables can be misleading as none of them touch lambda tables and just do duration.
You are 100% correct.

So I use dyno + MAF + BSFC and work backwards ;) = app. 17:1

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Re: Good Lambda/AFR for Diesel

Postby rlees85 » Thu Sep 27, 2012 5:32 pm

To be fair, the map for the 306 that I mentioned, the injection duration has not been adjusted, so that is good. The map is one of Steve's (or pro_steve). I seen a few threads on ecuconnections where you and him are discussing stuff so I think you know him...

The map itself is a good map, just a little smokey, but that said my 306 had over 200k on it and sounded like a Massey Ferguson...

anyway about Lambda, I thought 17/17.5 but maybe thats a little too much air on the 406. Can I ask are you using approx 17 at low RPM or high?

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Re: Good Lambda/AFR for Diesel

Postby Relic » Thu Sep 27, 2012 6:24 pm

pro_steve seems like a nice chap.
Dont really know him that well TBH.

My lambda tables below...not that you would use anything like this.
A peugeot engine is not a honda engine.
Some of the major differences being cold forged alloy engine, 17:1 compression and offset crankshaft.

Its currently fueled so lambda this low wont take effect on fuel until 30c and 960mbar atmospheric.
So it will run leaner (identical IQ) than this at all other times with colder and/or denser air.
I had a choice wether to fuel it for the summer so that fuel is never cut unless its outside 30c 960....or fuel it for all out power at winter where the lambda would always cut the fuel unless its 1060mbar and 0c

The pro :shifty: remaps give a light puff of smoke when going full thottle...but are pretty smokeless other than that
Its not a case of look in the mirror at full throttle and see black smoke everywhere.
At night in the headlights you see a faint haze if anything.

SMOKE LIMIT = 3.00 parts / million
test1 = 1.55
test2 = 0.15
test3 = 0.15
test4 = 0.26
mean= 0.18

LAMBDA.pdf
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Re: Good Lambda/AFR for Diesel

Postby rlees85 » Thu Sep 27, 2012 8:36 pm

Cheers, more good information ;) even if its not for the 406, still helps get my head around the 'way of thinking', to nice one for that.

Just installed Tuner Pro for a look, can't get it to see the values inside any of my bins but thats probably because I haven't worked out how to use it properly yet.

Apart from the smooth function (I figured that no human can make a map as smooth as the one in your PDF ;) ) does tuner pro do anything else that winols doesn't?

I'll be sticking with winols, but its good to have other tools too.

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Re: Good Lambda/AFR for Diesel

Postby Relic » Thu Sep 27, 2012 9:16 pm

rlees85 wrote:Just installed Tuner Pro for a look, can't get it to see the values inside any of my bins but thats probably because I haven't worked out how to use it properly yet.

Apart from the smooth function (I figured that no human can make a map as smooth as the one in your PDF ;) ) does tuner pro do anything else that winols doesn't?

I'll be sticking with winols, but its good to have other tools too.


Tunerpro is deceptively powerful (although it doesnt do checksums unless you tell it how).
With winols it hunts for maps for you...although it dont find everymap....just obvious ones.
Tunerpro you have to hunt for maps yourself and create the tables (xdf file) that put a fence around the various maps.
This flexibility initially seems a drag creating all the tables manually...
..but you only do it once and then use it for the same software version.
Like a map pack for winols.

You can +-*/ selected values by the value entered.
You can copy from a compare file if you want to duplicate a previous remaps tables

You can also go hardcare where you tell it to reference data from a different area for parallel maps... or even modify those refernced values by formula.
You can go as far as referncing multiple tables and create a formula to generate the values on the fly.
.....

Oh! that map is hand crafted by mathematical formula :thumbup:
Pretty straightforward....the driver wish was another matter :wtf:

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