Does ECU adapt to and cancel out mods?
Discussion
Hi
If a stock monaro has a basic mod such as an exhaust fitted from which a small gain of power is seen, would the std ECU compensate and adapt out the performance gains over a period time and return the engine back to its original power. If this is the case, would it also adapt out any gains from a re-map?
Thanks in advance,
Jon
If a stock monaro has a basic mod such as an exhaust fitted from which a small gain of power is seen, would the std ECU compensate and adapt out the performance gains over a period time and return the engine back to its original power. If this is the case, would it also adapt out any gains from a re-map?
Thanks in advance,
Jon
No. I think a re-map changes the parameters in which the engine works, and the ECU then works from these new figures.
If you put an exhaust on, the ECU should recognise that exhaust gasses can move more freely, and will add fuel quicker when you accelerate. However, this will only be within the coded values, and why a re-map will liberate the most from any bolt on upgrade.
A tuner will know what new parameters should be entered (approximately) so will probably upload an approximate map, and will then be watching associated values in the tune, and see how the changes are affecting other sensors - tweaking the values on anything that will cause the engine to run less efficiently. The skill is in watching multiple values in each step of the rev range, to give a smooth map.
That's my layman's take on it, anyway. Maybe Ringram or someone can correct where I'm wrong. .
If you put an exhaust on, the ECU should recognise that exhaust gasses can move more freely, and will add fuel quicker when you accelerate. However, this will only be within the coded values, and why a re-map will liberate the most from any bolt on upgrade.
A tuner will know what new parameters should be entered (approximately) so will probably upload an approximate map, and will then be watching associated values in the tune, and see how the changes are affecting other sensors - tweaking the values on anything that will cause the engine to run less efficiently. The skill is in watching multiple values in each step of the rev range, to give a smooth map.
That's my layman's take on it, anyway. Maybe Ringram or someone can correct where I'm wrong. .
The adapting is generally through short term fuel trims (multiple changes a second) which aim to keep the engine running at stoich during the majority of conditions.
Over time the STFTs contribute to long term fuel trims, which are for adapting to more significant changes in the motor, so modifications etc.
These LTFTs are still included in the fuelling calculations when you go in Power Enrichment mode (high load situations / high throttle).
Now, when you improve airflow, often it will thus naturally run leaner based on the standard map.
The STFTs will as such be typically adding fuel to keep the mixture stoich. This means the LTFTs go positive. As these are still included when in PE mode, you're kept safely in the rich zone.
A good tune should mean the STFTs stay near 0 and the LTFTs will thus be 0 too. Often a remap will actually mean you're running a bit leaner than the factory tune, as that's pretty rich as standard...
Over time the STFTs contribute to long term fuel trims, which are for adapting to more significant changes in the motor, so modifications etc.
These LTFTs are still included in the fuelling calculations when you go in Power Enrichment mode (high load situations / high throttle).
Now, when you improve airflow, often it will thus naturally run leaner based on the standard map.
The STFTs will as such be typically adding fuel to keep the mixture stoich. This means the LTFTs go positive. As these are still included when in PE mode, you're kept safely in the rich zone.
A good tune should mean the STFTs stay near 0 and the LTFTs will thus be 0 too. Often a remap will actually mean you're running a bit leaner than the factory tune, as that's pretty rich as standard...
KMud said:
A more serious answer would be wear, but the implementation of LTFTs may be clumsy.
Possibly STFTs have their defined purpose, effectively driven off the O2 sensor keeping things stoich, and as they aren't part of PE mode, something was needed to deal with long term or more significant changes, and that was deemed a fairly simple method.If any of you have ever written software, generally as soon as you try and do something 'clever' or automatically, you expose yourself to making a proper cock up of things in certain situations. In something like a mass production ECM, I'd imagine they're probably fairly strict on keeping things as simple as possible, each 'feature' having its own very clearly defined set of parameters it's allowed to work within.
Although I'm sure we could come up with a better way of doing things for our situation, I'm sure the GM engineers could have too, but it wouldn't have been appropriate in other situations, and thus wasn't acceptable for the mass market.
LTFTs are off here too, sorry GM
ringram said:
I guess they are somewhat of a failsafe so it depends on the owner etc.
I think this is it really, they have to cater for all kinds of mugs mistreating these motors, whilst still building a reputation for unburstable reliability to make them a success.Just means there's more left on the table for us lot
ringram said:
A+
question: Ltft's suck, what use are they?
long term serviceability for mongs that don't service their cars or keep on top of them. squestion: Ltft's suck, what use are they?
t like sucking oil through the dipstick and never changing the filter plus other st leading to deterioration of he car the trims pull them back to center for emissions and stFirst mod for anyone should to always disable them (but you know this)
what are your views on MAFs?
ringram said:
Used to be the same argument as ltft.
But newer ones have inherent limitations removed, they support more flow.
aye saw the resolution on some of the new ones and the rates were nice, good for if you do regular altitude changes but how did we survive without ltft's and mafs?But newer ones have inherent limitations removed, they support more flow.
Going SD full next tune
What Im suggesting is that you dont need the maf to do that. The MAP sensor is there to do that specifically.
In the GM applications MAF is blended with SD until higher RPM when it takes over more.
MAF is not optimal in transient conditions.
Its a fallacy to say that varying conditions are only able to be managed by the MAF
In the GM applications MAF is blended with SD until higher RPM when it takes over more.
MAF is not optimal in transient conditions.
Its a fallacy to say that varying conditions are only able to be managed by the MAF
Gassing Station | HSV & Monaro | Top of Page | What's New | My Stuff