[Noob alert] Can remapping increase MPG?

[PrivateHireGuy]

As per title really.

2019 300 E SE.

Ta.

 

[markjay]

In a nutshell, yes.

Modern engines are increasingly designed to reduce NOx emissions (among other things), and it's relatively easy to regain mpg and/or power losses via a remap that increases NOx emmision levels above the manufacturer's spec for the engine but below any legal threshold.

 

[clk320x]

In a nutshell, yes.

Modern engines are increasingly designed to reduce NOx emissions (among other things), and it's relatively easy to regain mpg and/or power losses via a remap that increases NOx emmision levels above the manufacturer's spec for the engine but below any legal threshold.

but ethically is it fair to increase your cars burden on the environment and others health to save yourself a couple of pounds a fill?

 

[whitenemesis]

Modifying any part of the emissions systems is illegal and would render the car illegal for use on the public roads. MoT failure (not sure how it would be detected) and would render one's insurance void, easily detected should the company wish to investigate, to avoid paying out a big claim, or to recover costs from the insured

 

[markjay]

Modifying any part of the emissions systems is illegal and would render the car illegal for use on the public roads. MoT failure (not sure how it would be detected) and would render one's insurance void, easily detected should the company wish to investigate, to avoid paying out a big claim, or to recover costs from the insured

This has been covered before on the forum, and I think that the conclusion was that remapping isn't illegal as long as the emissions remain below the fail treshold of the MOT test.

Personally, I think that remapping should be illegal (as well as any other modification that alters the car's emissions), but given that it isn't, we shouldn't be scolding those who remap their car's engines.

 

[markjay]

As per title really.

2019 300 E SE.

Ta.

In a nutshell, yes.

Modern engines are increasingly designed to reduce NOx emissions (among other things), and it's relatively easy to regain mpg and/or power losses via a remap that increases NOx emmision levels above the manufacturer's spec for the engine but below any legal threshold.

One issue to consider, is that remapping isn't cheap, and the economic viability needs to be checked by comparing the estimated overall saving in fuel cost against the cost of remapping. This isn't straightforward though, because too many remappers advertise unrealistic gain figures (for both bhp and mpg).

 

[MCFastybloke]

Same as above just slower fingers.

 

[Gazwould]

One issue to consider, is that remapping isn't cheap, and the economic viability needs to be checked by comparing the estimated overall saving in fuel cost against the cost of remapping. This isn't straightforward though, because too many remappers advertise unrealistic gain figures (for both bhp and mpg).

Even more so is the box of frogs , for mine one said 120Nm gain when most remappers say 50Nm , they got taken to court in Stuttgart in 2019 and now advertise 70 Nm on their official website but even today some of RaceChip's retailers are slow to correct .










Some box manufacturers still advertise + 100 Nm .

 

[TeddyRuxpin]

Actually you don’t have to remove/delete/code out the EGR during a remap, and as such the NOx increase post-remap is not necessarily of note. In fact I would guess you won’t be able to find much hard info or sources on the affects of NOx output when remapping a Diesel engine while keeping EGR and DPF systems in place. I know because I’ve spent hours looking.

Especially true if the remap is post-MB diesel emissions software.

The removal of the EGR system is what drastically increases NOx production (although reduces soot and CO2, which are less harmful than NOx) but removing it is not the only source of the MPG gained from a remap. The torque is, as discussed.

Having said all that, I’m not sure the OP’s car is even a diesel, in which case NOx discussion is largely moot.

 

[markjay]

Petrol engines have EGRs and produce NOx, it's just not measured during MOT (only Diesel engines get the NOx tested), so you can do pretty much whatever you want with a petrol engine and no one will ever know.

 

[TeddyRuxpin]

The NOx from a 2019 petrol Mercedes is going to be extremely low and the point stands that disabling the EGR is not necessary for a remap.

Also, diesels don’t get NOx tests on MOTs.

 

[whitenemesis]

Personally, I think that remapping should be illegal (as well as any other modification that alters the car's emissions), but given that it isn't, we shouldn't be scolding those who remap their car's engines.

Scolding no one, just stating possible consequences/implications.
TBH I couldn't give a tinkers toss what people do to their cars, the potential to affect me personally and the environment generally is negligible.

 

[Teego]

Remapping can do whatever the guy selling you the remap says it can do.

 

[Supernoodle]

@PrivateHireGuy isn't your car a plug in hybrid? If you're only using it in ICE mode economy won't be great purely because of the weight.

For a remapper it's relatively easy to create more power, that's just more fuel and/or air and to hell with the cylinder pressure limits.
To gain a tangible improvement economy though without changing hardware, I'd like to see how they'd do that. It takes the best part of 3 years and many millions to develop a powertrain. Some guy isn't going to plug in a laptop and give you 10%.

 

[Bellow]

Personally, I think that remapping should be illegal (as well as any other modification that alters the car's emissions), but given that it isn't, we shouldn't be scolding those who remap their car's engines.

Despite it being one of the reasons ICE is being excluded from cities. Or is that part of the game plan to accelerate the eradication of all ICE - even untampered with ones?

 

[markjay]

Despite it being one of the reasons ICE is being excluded from cities. Or is that part of the game plan to accelerate the eradication of all ICE - even untampered with ones?

Yes, because it's no different in essence to someone buying a 6.2L AMG, or driving an old Diesel car, the cars will release more emissions than other smaller or newer cars, so we should discourage their use in city centres, but as long as it's not illegal we'll just need to tolerate it. That said, I'm all in favour of making remapping illegal, just as PDF removal was made an MOT failure.

 

[Bellow]

Yes, because it's no different in essence to someone buying a 6.2L AMG, or driving an old Diesel car, the cars will release more emissions than other smaller or newer cars,

Not necessarily true as a less stressed larger engine can have lower NOx than a smaller (esp turbocharged) one and it's NOx that is problematic in cities.
In an earlier post (on another thread) you said that larger engines should be penalised over smaller ones. Unfair if the larger engine (with say, half the mpg of the smaller one) only covers half the mileage of the smaller one - a very plausible scenario.

so we should discourage their use in city centres, but as long as it's not illegal we'll just need to tolerate it. That said, I'm all in favour of making remapping illegal, just as PDF removal was made an MOT failure.

I suspect that it is illegal in that the vehicle is supposed to adhere to its homologated emission levels throughout its life. In essence, it should, at any point in its life be able to pass the original test for homologation were it submitted to it.
Not being capable of that a vehicle should be submitted for IVA (Individual Vehicle Approval) and will be allocated emission status in accordance with the supporting documentation ie, the results of the EU test it has subsequently been subjected to. As that is impractical it would be classed as 'emissions unknown' which places it in a much costlier VED bracket and may make it hard to gain insurance.
That it is never enforced is moot. The emissions originally homologated are expected not to be exceeded - and obviously re-mapping inevitably raises NOx output beyond any homologated limit. Thus, the vehicle is no longer EU compliant.

 

[markjay]

Not necessarily true as a less stressed larger engine can have lower NOx than a smaller (esp turbocharged) one and it's NOx that is problematic in cities.
In an earlier post (on another thread) you said that larger engines should be penalised over smaller ones. Unfair if the larger engine (with say, half the mpg of the smaller one) only covers half the mileage of the smaller one - a very plausible scenario.


I suspect that it is illegal in that the vehicle is supposed to adhere to its homologated emission levels throughout its life. In essence, it should, at any point in its life be able to pass the original test for homologation were it submitted to it.
Not being capable of that a vehicle should be submitted for IVA (Individual Vehicle Approval) and will be allocated emission status in accordance with the supporting documentation ie, the results of the EU test it has subsequently been subjected to. As that is impractical it would be classed as 'emissions unknown' which places it in a much costlier VED bracket and may make it hard to gain insurance.
That it is never enforced is moot. The emissions originally homologated are expected not to be exceeded - and obviously re-mapping inevitably raises NOx output beyond any homologated limit. Thus, the vehicle is no longer EU compliant.

I am not sure that private owners changing the spec that their cars were tested with is currently prohibited.

The obvious example if fitting larger wheels with wider tyres, which affects emissions. Not only is it not prohibited, but you can actually buy it as an aftermarket kit directly from the car manufacturer, and it won't alter the car's classification for VED purposes.

You could argue that it should be illegal, and I'd agree with that (or at least that it requires the car to be reclassified).

But as things stand, cars are being taxed based on the spec as supplied from the factory, and changing these spec is not in itself illegal, other than were specifically stated (e.g. PDF removal).

 

[markjay]

Incidentally, my (non-Merc) EV is the top spec for the model range, and has a range on 20 miles less than the basic spec car. This is most probably in part due to the heavier weight of the higher-spec car, but the manufacturer says that this is predominantly due to the top spec car having 20" wheels while the basic spec car has 19" wheels. The manufacturer says that the difference in range stems from the additional friction of the wider tyre, additional weight, and other factors relating to the difference in air flow around the wheels. The difference in range is about 6%, but I dont know how much exactky the larger wheels are responsible for. Also, I don't have any figures to show the difference in mpg and emissions due to fitting bigger wheels on ICE cars, but I imagine that they are measurable and not insignificant.

 

[Bellow]

I am not sure that private owners changing the spec that their cars were tested with is currently prohibited.

If a remap took the engine-out NOx beyond say, EU6 limits, then the car is no longer EU6 compliant. Doubtful that that is entirely legal.

The obvious example if fitting larger wheels with wider tyres, which affects emissions. Not only is it not prohibited, but you can actually buy it as an aftermarket kit directly from the car manufacturer, and it won't alter the car's classification for VED purposes.

Only because the change is unmeasurable. Can said kit be optioned at time of vehicle purchase included in that single transaction or is its sale a separate transaction? I'll wager the the latter.

You could argue that it should be illegal, and I'd agree with that (or at least that it requires the car to be reclassified).

But as things stand, cars are being taxed based on the spec as supplied from the factory, and changing these spec is not in itself illegal, other than were specifically stated (e.g. PDF removal).

Altering the emissions by tampering with emissions kit is obviously a crime in itself but what happens within the engine (that is affected by a remap) should also be scrutinised.
The VED issue is neither here or there regarding NOx. NOx is monitored in cities, deemed problematic, and instead of dealing with the emitters all ICE is slowly but surely being excluded. In terms of NOx and particulates my 5.7l V8 running on LPG is as clean as your EV. CO2 a different picture - but CO2 isn't the problem in a city.