# engine remapping does it improve fuel efficiency



## kieran160 (30 Jun 2008)

hi all

i have really started to feel the difference at the pumps each week, a fill of diesel costs me $85 now compared to $70 last year.

tonight i saw a programme on itv about fuel and how to save on cost. it showed a diesel jeep after getting the ecu remapped and i was suprised to see the mpg went up by 7mpg. remapping the ecu results in an increase of about 15% in fuel efficiency in diesel engines.

have any readers tried it and what were the results? i have been told there is a couple of firms in the country that can do it, no idea on cost doh!


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## Iceman732 (30 Jun 2008)

Remapping can definitely improve the fuel efficiency of cars. The level of improvement depends on each individual vehicle, you could also look at slowing down air intake etc... in order to improve efficiency. Naturall you'll sacrifice speed but when you paying €15 more for a fill of petrol it's something you should definitely look at.      

Remapping can void warranties and the likes too, it really depends on what you do to the ECU. Most people remap the ECU to increase speed. For example on a Audi A4 putting out 130-140 BHP you can up the BHP to about 175BHP that's a serious increase but you're going to end up driving the engine through the floor of your car. 

Personally it's not something I'd recommend lightly, you could mess with your gear ratio in order to increase your efficiency. Naturally the results won't be as staggering.


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## mathepac (30 Jun 2008)

kieran160 said:


> ... remapping the ecu results in an increase of about 15% in fuel efficiency in diesel engines...


I think the key thing here is that ECU re-mapping *may* result in an increase in fuel efficiency, as can changes in driving style, journey planning, etc.

A lot of this depends on the engine, the ECU, the map that's downloaded (whether its generic or custom), the re-mapper and the driver's requirements.

Some maps (and so-called tuning boxes) simply overfuel to increase bhp and maybe torque, do nothing to save fuel and may result in short-lived clutches and flywheels.


kieran160 said:


> ... have any readers tried it and what were the results? ...


I've had one of my cars custom re-mapped. Its original 130bhp is now a very smooth controllable 175 bhp, 300 ft/lbs of torque and typically does 56 mpg in a mix of driving conditions.


kieran160 said:


> ... i have been told there is a couple of firms in the country that can do it, no idea on cost doh!


My car was done in the UK but I'm sure there are firms here who can do this work.

My suggestion would to look for someone who can put your car on a rolling road, check your ECU for faults, re-map the car to your requirements and show you the results on the rolling road again.

Contrary to popular belief, re-maps, as distinct from piggy-back chips  or tuning boxes are undetectable by dealers' diagnostic software.

Your insurers will need to know about any changes to your car's software.


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## quinn2008 (9 Sep 2008)

hi all... just a quick question?. I had my car  re-mapped but what i have noticed is the extra power is sometimes there on take off and sometimes its not but when i reach 2000 rpm the turbo kicks in and you can feel the power.can any body tell me why it is not there all the time. I was told there could be a problem with the air intake valve. can any body help. Thanks


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## dieseldave (9 Sep 2008)

I know a man thats drives a Sante fe 2.2 and a Merc Sprinter for well known parcel delivery company, has had them both chipped and says the accereration is better and MPG is up 5-7 mpg depending on the driving mood.


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## RS2K (10 Sep 2008)

I'm sceptical. Any state of tuning is a compromise. Power, torque, economy, and reliability. Emissions too.

I fail to see how fiddling with the ECU can even hope to make gains on 1,2, & 3 above without scarificing 4.

I fully accept power on turbo engines can be upped considerably, but what about emissions?

35% (as mentioned above) is a big power hike, but are the vehicles brakes, suspension, engine and drivetrain designed/able to handle it?

What about insurance and disclosure?


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## Caveat (10 Sep 2008)

mathepac said:


> I've had one of my cars custom re-mapped. Its original 130bhp is now a very smooth controllable 175 bhp, 300 ft/lbs of torque and typically does 56 mpg in a mix of driving conditions.


 
That all sounds nice - any downside encountered? emissions etc?


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## BOF (11 Sep 2008)

RS2K said:


> I'm sceptical. Any state of tuning is a compromise. Power, torque, economy, and reliability. Emissions too.
> 
> I fail to see how fiddling with the ECU can even hope to make gains on 1,2, & 3 above without scarificing 4.



The car manufacturer has to give a 'default' engine map that will work with various grades of fuel down to really poor grade non-European fuel.  Assuming your car will only ever be at a European pump then you can fine-tune your car more effectively, so yes you can re-map and improve on all of the above to varying degrees of success depending on how tuned the car is beforehand.



RS2K said:


> What about insurance and disclosure?



AFAIK they can't prove a re-map.  So disclosure is up to your conscience.


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## kfk (11 Sep 2008)

BOF said:


> The car manufacturer has to give a 'default' engine map that will work with various grades of fuel down to really poor grade non-European fuel. Assuming your car will only ever be at a European pump then you can fine-tune your car more effectively, so yes you can re-map and improve on all of the above to varying degrees of success depending on how tuned the car is beforehand.


 
Any idea why the car manufacturer's have to give a 'default' engine map? Surely it would make more sense to tune engines according to the grade of fuel that would be used.


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## RS2K (11 Sep 2008)

BOF said:


> The car manufacturer has to give a 'default' engine map that will work with various grades of fuel down to really poor grade non-European fuel.  Assuming your car will only ever be at a European pump then you can fine-tune your car more effectively, so yes you can re-map and improve on all of the above to varying degrees of success depending on how tuned the car is beforehand.
> 
> 
> 
> AFAIK they can't prove a re-map.  So disclosure is up to your conscience.



Remaps can easily be discovered. A basic principle of Insurance is "utmost good faith". It's nothing to do with choice.


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## ollie323 (15 Sep 2008)

Sorry to go off topic but:
I've found that easing the driving style in a diesel returns a much smaller saving than in a petrol. My proof: 16 year old civic driven normally gives 45mpg. Driven gently gives up to 67mpg.
Spanking new diesel kia ceed driven normally gives 50mpg, driven gently gives 55mpg.
Anyone got any idea why this might be?

Anyway, about remapping for mpg. I believe it gives a small return alright but you'd HAVE to tell the insurance company and you just know they are going to salivate heavily when you say the word "remap", therefore wiping out any fuel savings. I would also guess that they won't listen to you when you say you drive gently for more mpg and therefore are guaranteed to never end up in a ditch or up to the windscreen wipers in another car! I dunno, maybe someone here works in car insurance and will tell me otherwise. I'm quite happy to be corrected!

ollie


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## mathepac (15 Sep 2008)

quinn2008 said:


> hi all... just a quick question?. I had my car  re-mapped but what i have noticed is the extra power is sometimes there on take off and sometimes its not but when i reach 2000 rpm the turbo kicks in and you can feel the power.can any body tell me why it is not there all the time. I was told there could be a problem with the air intake valve. can any body help. Thanks


I suspect this is a generic (diesel ?) re-map and that the person telling you that you have a "problem with the air intake valve" is the mapper. Did he call to your house or did you go to his premises and have a custom map done?

If its a diesel engine there is no such thing as an "air intake valve" and I suspect the reference is to a mass air-flow sensor or MAF, which can give problems, particularly when used with after-market air-filters that require periodic cleaning and oiling. If oil is applied to the filter on the clean or turbo side, it can coat the MAF probes and stop them working. This scenario usually results in a non-functioning MAF which probably won't give the intermittent fault you describe. If its intermittent, then I would suspect poor electrical connections in the MAF circuit.

Again if its road-going (non-racing) diesel engine, it would be unusual to have the turbo on full boost below 1500 / 1800 rpm and some generic after-market re-maps deliver all the torque in a big lump at about 2000 / 2200 rpm, tailing off around 3000 / 3500 rpm. BTW, some cars off the production line do this as well, so its not a criticism of generic re-maps as such.

As an aside, if you are revving s diesel engine hard in 1st and 2nd gear or indulging in 2nd gear launches away from traffic lights, don't expect your clutch and fly-wheel to last. The torque produced by diesels is phenomenal and 1st (and even 2nd) gear are designed just to get things rolling.

I'd suggest you get it checked by a good independent diesel expert in your area. If your car is petrol, you can ignore most of this post.


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## mathepac (15 Sep 2008)

Caveat said:


> That all sounds nice - any downside encountered? emissions etc?


Yes, the somewhat fragile clutches and (dual-mass on VAG) fly-wheels fitted to some cars may not last if a re-mapped car is taken to the rev-limits through all the gears, but on the emissions side all is good - still well within the band for the original unmodified engine.

In a partial answer to another question in the thread, upgrading key components (brakes, clutch, fly-wheel, fuel-pump, injectors, turbo, inter-cooler, fuel-cooler, exhaust, manifolds, oil-cooler, etc are all part of matching performance with safety, emissions and reliability. Professional tuners (re-mappers) will provide packages of component upgrades aligned with a users performance requirements and won't do the re-mapping without the rest of the package to match. This is how you can very quickly get involved in silly amounts of money for relatively small performance gains, quicly negating the gain in fuel economy which might have been the objective at the start of the exercise.

Its a slippery slope.


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## mathepac (15 Sep 2008)

kfk said:


> Any idea why the car manufacturer's have to give a 'default' engine map? Surely it would make more sense to tune engines according to the grade of fuel that would be used.



Almost all modern cars are produced with mutiple engine maps as OE, depending on the market they are being sold into (for example - temperate climate / good fuel, equitorial climate / poor quality (high sulpher) fuel, equitorial climate / good  fuel, etc. These are then simply enabled or disabled during production. It simplifies the task of producing the ECU and software - no variations.

VAG have at least three "maps" in their ECUs and rumour has it that inventive people store alternative maps in the spare locations and swap between them depending on the use (or abuse) the car is going to be subjected to. School run = Map A factory fitted; Week-end track day = Map B cutom designed; Week-end endurance racer = Map C custom designed.


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## dieseldave (15 Sep 2008)

ollie323 said:


> Sorry to go off topic but:
> I've found that easing the driving style in a diesel returns a much smaller saving than in a petrol. My proof: 16 year old civic driven normally gives 45mpg. Driven gently gives up to 67mpg.
> Spanking new diesel kia ceed driven normally gives 50mpg, driven gently gives 55mpg.
> Anyone got any idea why this might be?
> ...


 
ollie, it's mad that you said that, my auld lads 1.4 petrol corolla 06, everytime the I take it for a drive and check his MPG on the computer it's up to 62 MPG!, he's a serious sunday driver practicing everyday! My auris 1.4 d4d does an average of 50.


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## ollie323 (16 Sep 2008)

dieseldave said:


> ollie, it's mad that you said that, my auld lads 1.4 petrol corolla 06, everytime the I take it for a drive and check his MPG on the computer it's up to 62 MPG!, he's a serious sunday driver practicing everyday! My auris 1.4 d4d does an average of 50.


Hmmm.......so i'm not crazy then! You should let him have the auris for a while to see how it does.......!!

ollie


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