What is remapping? Is it really beneficial?

[V12]

Are CO2 emissions independently tested for every model-type ?
I'm guessing they must be, for taxation purposes.
But they're hardly critical to sales figures - unlike MPG claims.

Due to the different taxation classes, emissions is becoming more relevant to the end user.

I know 2 or 3 people that jumped into the new 1 series as soon as they produced a version with under 100g/km meaning the road tax is free.

 

[V12]

From what I know of CO2/MPG tests, most producers carry them out with custom maps - not the production maps used for the cars on sale...

That said - I do believe manufacturers will operate within a safe margin; so you may be able to eek out a little more performance out of the engine... at the risk of compromising the reliability...

Do you have a source for that info?

 

[Lord-WYBMAnE220]

Due to the different taxation classes, emissions is becoming more relevant to the end user.

I know 2 or 3 people that jumped into the new 1 series as soon as they produced a version with under 100g/km meaning the road tax is free.

I meant to sales within the tax bracket.

 

[Spinal]

Do you have a source for that info?

IIRC it was on the guardian as part of some report blaming car manufacturers for all sorts of tricks for the figures, including disconnecting alternators, over-inflating tyres, fiddling the ECUs to use higher gears, etc.

I'll try to dig it up later.

 

[Lord-WYBMAnE220]

IIRC it was on the guardian as part of some report blaming car manufacturers for all sorts of tricks for the figures, including disconnecting alternators, over-inflating tyres, fiddling the ECUs to use higher gears, etc.

Hehe

 

[SteveX]

There's some good points on here, and I always thought the stock remap is to try and cover as many bases as possible, based on what that projects goals are, there will be a compromise in performance to try and achieve better MPG etc if that's what they want for that model and vise versa.

However, I haven't heard anyone mention their marketing strategies or costs, remember that in many cars or particular model cars from any marque, it is only one in a wide range of cars marketed at a different target audience, we've seen a lot of engines (especially in the VAG group) used on so many platforms in various states of 'tune' with little or nothing done to the engine. If the same engine, or other engines in the range produced very similar output and results to other engines then there wouldn't be any point in having that in the range. All of these models with the same lump have been tuned to suit the target market and where the model fits in the range (as well as other factors like bellow).

The stakeholders and shareholders calling the shots won't simply say 'make this model perform the absolute best you can', I would imagine there's a list of acceptable parameters and goals, and that's what they try to get to, like any project. It's also as much about how much time they have to spend on R&D on a certain project as anything else.

Lets also not forget how many different legislation and local laws they have to comply with such a smog laws in so many different countries of their target market.

So, I don't think for one minute it is as clearly cut as a lot are suggesting.

Lets take aftermarket headers for example, they are known to make gains on the M113, yet you will still get people in the 'Mercedes and AMG the huge company they are know what they are doing' camp. Yes, they do know what they are doing, but that doesn't mean they are going to spend a massive chunk of their R&D budget or manufacturing budget in producing the best headers on the planet for that car.

As with everything that a company produces to make a profit, there are always compromises and other hidden agendas that we know nothing about.

 

[Lord-WYBMAnE220]

There's some good points on here, and I always thought the stock remap is to try and cover as many bases as possible, based on what that projects goals are, there will be a compromise in performance to try and achieve better MPG etc if that's what they want for that model.

However, I haven't heard anyone mention their marketing strategies or costs, remember that in many cars or particular model cars from any marque, it is only one in a wide range of cars marketed at a different target audience, we've seen a lot of engines (especially in the VAG group) used on so many platforms in various states of 'tune' with little or nothing done to the engine. If the same engine, or other engines in the range produced very similar output and results to other engines then there wouldn't be any point in having that in the range.

The stakeholders and shareholders calling the shots won't simply say 'make this model perform the absolute best you can', I would imagine there's a list of acceptable parameters and goals, and that's what they try to get to, like any project. It's also as much about how much time they have to spend on R&D on a certain project as anything else.

Lets also not forget how many different legislation and local laws they have to comply with such a smog laws in so many different countries of their target market.

So, I don't think for one minute it is as clearly cut as a lot are suggesting.

Lets take aftermarket headers for example, they are known to make gains on the M113, yet you will still get people in the 'Mercedes and AMG the huge company they are know what they are doing' camp. Yes, they do know what they are doing, but that doesn't mean they are going to spend a massive chunk of their R&D budget or manufacturing budget in producing the best headers on the planet for that car.

As with everything that a company produces to make a profit, there are always compromises and other hidden agendas that we know nothing about.

So, what are you saying ?

 

[SteveX]

So, what are you saying ?

There are so many other contributing factors that we don't even see, it's impossible to say what was on the table when they decided to produce the car, or why they come as they do in their state of 'tune' from the factory.

We've no idea what was exactly on their mind when they 'mapped' the car.

 

[Dieselman]

One major point to take into account regarding remapping petrol engines is that the Lambda sensor always holds the mixture very close to stoichiometric, so other than advancing the ignition timing, or letting in more air by opening the throttle more what can a remap do?

Diesel engines an have the fuel volume increased, which yields more power at the expense of engine longevity due to turbo and piston crowns suffering from excess EGT.

 

[Lord-WYBMAnE220]

One major point to take into account regarding remapping petrol engines is that the Lambda sensor always holds the mixture very close to stoichiometric, so other than advancing the ignition timing, or letting in more air by opening the throttle more what can a remap do?

Diesel engines an have the fuel volume increased, which yields more power at the expense of engine longevity due to turbo and piston crowns suffering from excess EGT.

Yep, cooked turbos and exhaust valves are the usual symptoms of remapping - and of EGR-deletes (EGR's are designed to reduce combustion temps by substituting atmospheric O2 with exhausted CO2).
EGR-deletes may be good for keeping the soot out of your inlet manifold and thereby saving your turbo from swirl-flap caking and breaking - but like everything else in this life, there's no such thing as free lunch.

 

[chris200]

One major point to take into account regarding remapping petrol engines is that the Lambda sensor always holds the mixture very close to stoichiometric, so other than advancing the ignition timing, or letting in more air by opening the throttle more what can a remap do?

Diesel engines an have the fuel volume increased, which yields more power at the expense of engine longevity due to turbo and piston crowns suffering from excess EGT.

As a result of this thread my own brief flirtation with the idea of a remap or ecu upgrade on my C200 CDi W204 has now been decided. I'm going to leave the car as it is and get on with more important stuff in life!

 

[Dieselman]

Yep, cooked turbos and exhaust valves are the usual symptoms of remapping - and of EGR-deletes (EGR's are designed to reduce combustion temps by substituting atmospheric O2 with exhausted CO2).
EGR-deletes may be good for keeping the soot out of your inlet manifold and thereby saving your turbo from swirl-flap caking and breaking - but like everything else in this life, there's no such thing as free lunch.

Deleting the EGR reduces overall gas temperature.

The argument goes that introducing an inert gas will reduce very localised high temperatures at low fueling conditions, but overall the combustion temperature is reduced.

I have an EGT gauge which shows a reduced temperature of ~50c when the EGR is deleted.

How did diesels cope before EGR was used?

 

[Lord-WYBMAnE220]

Deleting the EGR reduces overall gas temperature.

The argument goes that introducing an inert gas will reduce very localised high temperatures at low fueling conditions, but overall the combustion temperature is reduced.

I have an EGT gauge which shows a reduced temperature of ~50c when the EGR is deleted.

How did diesels cope before EGR was used?

Google EGR.
It was originally introduced to combat acid rain from exhaust emission of NOx's, which are produced at higher combustion temps.
Reducing O2 as a combustion reagent reduces those temps - and CO2 is drawn back into the mixture to 'substitute' for O2.

 

[Dieselman]

I don't need to Google it, I have an EGT gauge fitted to check the result.

I know the theory, but EGR operates only at very low load conditions, so the localised high temperatures aren't an issue as the overall temperature is very low.

 

[Lord-WYBMAnE220]

I don't need to Google it, I have an EGT gauge fitted to check the result.

I know the theory, but EGR operates only at very low load conditions, so the localised high temperatures aren't an issue as the overall temperature is very low.

It's good to get realworld feedback on this kind of stuff.
Not enough people report it.

 

[Benzowner]

The only way to reduce CO2 output is to reduce engine size.

Disagree with that, CO2 emissions, for some reason, and I don't know why, are also dependent on your wheel and tyre size. There was an MB catalogue I viewed a few years ago on an E Class I think, where larger wheels and tyres had an adverse affect on CO2 and pushed the car into a higher tax bracket. I can only think it must be more drag

 

[Lord-WYBMAnE220]

Disagree with that, CO2 emissions, for some reason, and I don't know why, are also dependent on your wheel and tyre size. There was an MB catalogue I viewed a few years ago on an E Class I think, where larger wheels and tyres had an adverse affect on CO2 and pushed the car into a higher tax bracket. I can only think it must be more drag

We were talking about CO2-output as a mapping parameter, ie - WRT to the engine.
You're talking about CO2 output per unit of gross vehicle weight.

 

[SteveX]

One major point to take into account regarding remapping petrol engines is that the Lambda sensor always holds the mixture very close to stoichiometric, so other than advancing the ignition timing, or letting in more air by opening the throttle more what can a remap do?

Diesel engines an have the fuel volume increased, which yields more power at the expense of engine longevity due to turbo and piston crowns suffering from excess EGT.

That's not strictly true, that can only be the case if a wideband from factory is fitted and the car is programmed as such (or an aftermarket ECU and wideband is fitted).

A lot of older cars aren't.

 

[Dieselman]

That's not strictly true, that can only be the case if a wideband from factory is fitted and the car is programmed as such (or an aftermarket ECU and wideband is fitted).

A lot of older cars aren't.

So a punter on here wants a remap on a C230k, what can be done. Nothing as the volume of air is fixed.

 

[MattDC]

remaps taken to extremes and done unsafely can and will cause damage.....

but take the Mercedes engine lineups for example, some of these are restricted by the map to give lesser performance in order to meet insurance groupings and other targets for certain markets....

take the c200 and c220 CDI's (W204007 and W204008), there is absolutely no difference between the 2 other than the map on the ecu, with this in mind there is no reason to expect a moderate remap of the 200 to have a detrimental effect over standard.

In fact other than the turbo and injectors there is no difference in other components when you move up the range further to the c250!

remapping is also often undertaken in order to smooth the power delivery and provide a more driveable car, the headline torque and bhp figures are not what you should be looking for, more the area that is under the curves.....