Lambda-control Self Learning With Standard Or Wide Band Sensors.

[TEKNOPUG 3]

Hi there,

 

been having a read through a load of aftermarket management sites for pros and cons, prices etc.

 

A few have the ability to self-learn and adjust the maps via wide band lambda sensors. Now this sounds like a very good idea. But how often is the system likely to update? Surely once it's been mapped than it should stay constant unless something serious goes wrong?

 

So is this a specification that I should mark as essential or just a "nice to have" but shouldn't be a deciding factor?

 

Opinions please....

[Revla 2]

Hi there,

 

been having a read through a load of aftermarket management sites for pros and cons, prices etc.

 

A few have the ability to self-learn and adjust the maps via wide band lambda sensors. Now this sounds like a very good idea. But how often is the system likely to update? Surely once it's been mapped than it should stay constant unless something serious goes wrong?

 

So is this a specification that I should mark as essential or just a "nice to have" but shouldn't be a deciding factor?

 

Opinions please....

 

Hello,

 

IMO it is fine without, although it may be nice to have it adjusting to get the fuelling spot on? You could fit it later if you think it is necessary?

 

Trev

[TEKNOPUG 3]

The thing is, not all ecu's offer this facility. So I'd have to decide before I buy.

[Revla 2]

The thing is, not all ecu's offer this facility. So I'd have to decide before I buy.

 

What ECU are you thinking of then?

 

The KMS & Emerald can run this........

 

Trev

[TEKNOPUG 3]

Those are a couple that I have looked at but Emerald doesn't mention that it has a self learning ability, whereas the KMS does.

[Revla 2]

Those are a couple that I have looked at but Emerald doesn't mention that it has a self learning ability, whereas the KMS does.

 

Give Emerald a call, they are very helpful - I'm almost sure the latest does run wide band.........

 

Trev

Edited October 2, 2006 by Revla

[pdd144c 0]

Last time I spoke to Dave he was developing a self-learn function. Not because you need it, more because people 'wanted it'.

 

If its mapped correctly in the first place its not really needed is it.

[TEKNOPUG 3]

Last time I spoke to Dave he was developing a self-learn function. Not because you need it, more because people 'wanted it'.

 

If its mapped correctly in the first place its not really needed is it.

 

 

Well this was what I was thinking. Unless you have a drop in fuel pressure or a blocked injector, I can't see how the AFR can change that much?

[pdd144c 0]

Correct. Just run a AFR gauge to keep an eye on it all...

[Ryan 99]

I've heard a few stories about self-learning ECUs (although mostly the jap badge-whore stuff). It sounds very much like they are for people who expect everything to bolt on and magically work without any proper setting up time.

 

They're probably OK for getting everything in the right ballpark, but no match for a proper setup by an experienced mapper.

[tom_m 0]

i'm going with emerald andy

[James_R 3]

On a turbo it can be a nice "safety" feature mind, could set it to kill the engine/reduce boost if it falls below a certain AFR at full throttle

 

Butno not essential, and a certain AFR doesn't mean max power, can be a different AFR for each site makes max power.

[Guest BrainFluid]

A friend of mine mentioned that his ecu is self learning.

 

Apparently they can be 'reset' to start learning again, so if you do somthing that warrents that, you press the reset button and the car runs like s*ite for a while while it learns again.

 

Oh, and it will only learn what you offer. If you never go over 5000rpm for example it will run like s*ite if ever you did go over 5000rpm because it hasnt had the opportunity to learn that yet, if you catch my drift.

 

Nate.

[TEKNOPUG 3]

From what I've read about the self learning, if the AFR for example, keeps dropping below the set threshold, it will eventually rewrite the map to a new setting to accomodate. But surely if it's running a wide-band system it will constantly be adjusting the fueling/ignition to keep to the AFR settings anyway? So what's the point in it "learning" and making a new adjustment to the map? It sounds like a load of sales-bull for something that any system does anyway and that you don't need.

 

Or am I miss understanding something?

[pdd144c 0]

'sales-bull' is exactly what it is!

[tom_m 0]

i think you're describing the same thing there andy.

 

with a self learning system you set a target AFR and allow the ecu to adjust fuel and ingnition map within a certain tolerance to maintain that figure.

 

with a conventional ecu you map to the target AFR; when running the ecu sees the inputs to the engine (map sensor and throttle postion) and uses the apropriate bit of the map to give the engine fuel and ignition which will always be the same amount, unless you change the map

 

i think...

 

in theory if your ecu is propperly mapped in the first place, self learning is a gimmick.

 

however if you do mods that change the amount of air getting into the engine a mapped ecu will not 'see' the extra flow and consequently run lean, because it can only use the pre existing map. here self learning will see that the AFR is lean and be able to increase the fueling to accomodate.

Edited October 3, 2006 by tom_m

[TEKNOPUG 3]

Cool - nice to be right about something occasionally. I just couldn't get my head around why something that is dynamically altering the settings would require a feature that permanently changed the settings?

[TEKNOPUG 3]

i think you're describing the same thing there andy.

 

with a self learning system you set a target AFR and allow the ecu to adjust fuel and ingnition map within a certain tolerance to maintain that figure.

 

with a conventional ecu you map to the target AFR; when running the ecu sees the inputs to the engine (map sensor and throttle postion) and uses the apropriate bit of the map to give the engine fuel and ignition which will always be the same amount, unless you change the map

 

i think...

 

 

No, not from my understanding. From what I've read Tom, if you have a base map of settings and then something changes to require a different fuel input (for example) after a while, the ecu will permanently change the map to the new setting. Like if you get a drop in fuel pressue from a faulty pump. Then, if you fix whatever was causing the difference (ie a new fuel pump) after a while the ecu will "learn" the new settings and adjust the map accordingly.

 

But if the ecu if constantly monitoring the AFR, comparing it to what the map says it should be and continually making adjustments in real-time, why would there be a need to re-write the map?

 

Hence, is "self-learning" a load of bull?

[pdd144c 0]

Andy, from what i've seen self-learn only adjusts fueling. If thats the case it will still need to be dyno'ed to get the best results.

[TEKNOPUG 3]

however if you do mods that change the amount of air getting into the engine a mapped ecu will not 'see' the extra flow and consequently run lean, because it can only use the pre existing map. here self learning will see that the AFR is lean and be able to increase the fueling to accomodate.

 

But that isn't "self learning" though Tom. Surely that's just what a wide-band lamba system does anyway? Monitor AFR and adjust fueling/igntion accordingly? Obviously it will only make adjustments to keep to the map figures. But a self-learning system isn't going to see a big increase in air-flow and make adjustments to the map to get max power/torque. Only a rolling road session can do that.

If that was the case then you'd never need an RR session. You could just install the ecu to any engine and take it for a drive and it would map it perfectly. And then if you made any changes (boost, TB's, cc etc), just go for a spin and it would remap again for max power/torque! If only.....

[mos 1]

if i remember correctly

when i spoke to mattsav about this, around how much use this function will be for me when i install the kms stuff he said it will probably only prove to be of real value to get the car up and running initially so you can drive it of sorts, before taking it to be mapped properly on a rolling road

[TEKNOPUG 3]

From the Emerald website:

 

"Self learning

 

In addition to closed loop running the lambda sensor is also used in some EMS as part of a self-learning system. For example if the fuel pressure regulator in your car is working incorrectly and supplying less pressure than it should, the mixture will probably be a bit lean. The Lambda sensor feeds this back to the EMS which then richens up the fuelling. If this is happening consistently then the EMS knows that the mixtures are always a bit lean and will permanently richen up the mixture. It has learned that the mixture is lean and that richer mixtures are needed, and will always run this correction. If the pressure regulator is subsequently replaced or repaired, the EMS will then gradually re-learn the new requirements. This self-learning process occurs in most manufacturers EMS but is rarer in after-market systems. Self-learning of mixture strength is totally dependent on the Lambda sensor"

 

So as I say, I don't see the point of it making permanent adjustment if it is making real-time adjustments anwyay. Except possibly for cold-starts?

[tom_m 0]

But that isn't "self learning" though Tom. Surely that's just what a wide-band lamba system does anyway? Monitor AFR and adjust fueling/igntion accordingly? Obviously it will only make adjustments to keep to the map figures. But a self-learning system isn't going to see a big increase in air-flow and make adjustments to the map to get max power/torque. Only a rolling road session can do that.

If that was the case then you'd never need an RR session. You could just install the ecu to any engine and take it for a drive and it would map it perfectly. And then if you made any changes (boost, TB's, cc etc), just go for a spin and it would remap again for max power/torque! If only.....

 

well yes and no, what you're describing is closed loop lambda control and:

 

it is not recommended to use the closed loop lambda control on turbo charged vehicles or more than 25% throttle on normally aspirated vehicles.

 

closed loop trims the fuel at cruise and is not a permenant change to the fuel map

Edited October 3, 2006 by tom_m

[TEKNOPUG 3]

So there are some benefits to self-learning but not enough to make it an important factor when considering an ecu?

 

I think that it's gonna have to be an Emerald in that case. The KMS is cheaper but you get £200 worth of mapping by DW with the Emerald. So the extra cost kind of evens itself out. And they've mapped TT's before so they know what they are doing (I hope).

 

Right, that's that sorted. Just need a big wad of cash....

[pdd144c 0]

The map Dave did for my TT was brilliant.