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High Fuel Consumption After Installing Aftermarket Exhaust (Slip-On Only)

aftermarket exhaust consumption slip-on mufflers high consumption

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#1 pazof

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Posted 07 February 2019 - 11:25 am

Mornings to everyone. After replacing the stock pipes a couple of months ago with some GPR Furore Nero ones I have noticed that my fuel consumption has gone way up. With the stock pipes the bike would average around 5.5L/100km in-city, now with the GPR ones it's easily averaging at least 7.5L/100km in the city. That's about 25% increase in fuel consumption. Is this normal? I was under the impression that when installing aftermarket pipes the consumption should normally go down, not up :(

 

All I did was remove the stock end cans and install the new ones (so simply slip-ons + link pipes, not a full system). Db killers are installed, there are no catalytic converters (planning to install those as well), no power commanders or anything - the rest of the bike is pretty much stock.

 

Can it be that I did something wrong? It was the first time I replaced pipes myself, but I didn't really see much margin for error, it was a pretty straightforward process.

As a side note, I'm not interested in performance increase or anything, I'm quite happy with the bike as it is - I really just wanted a bit more vroom vroom (and the weight reduction doesn't hurt either)...

 

Would greatly appreciate any insight or advice as to whether there is anything I can do about this. Big thanks to everyone in advance for your time.

 

The mufflers:

https://www.gpr-moto...r---furore-nero



#2 JMC

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Posted 07 February 2019 - 12:04 pm

I would guess your revving a bit more than before due to the nice new sound your bike makes, I know I do  :P



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#3 pazof

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Posted 07 February 2019 - 12:18 pm

I would guess your revving a bit more than before due to the nice new sound your bike makes, I know I do  :P

 

I sure did!  :lol:

 

...But after seeing how expensive it was, I cut it short - and still, even with the most fuel-economic behavior, it's never gone under 7L/100km :(



#4 CrashTestDuffy

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Posted 07 February 2019 - 01:50 pm

O2 sensor and/or CO levels possibly?

#5 fixitsan

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Posted 07 February 2019 - 03:51 pm

If the O2 sensor is connected still, then a better flowing exhaust will clear waste gasses more readily, the O2 sensor may see that as a drop in carbon monoxide level and tell the ECU it is okay to enrichen the mixture a little bit


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#6 pazof

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Posted 07 February 2019 - 04:27 pm

If the O2 sensor is connected still, then a better flowing exhaust will clear waste gasses more readily, the O2 sensor may see that as a drop in carbon monoxide level and tell the ECU it is okay to enrichen the mixture a little bit

Interesting. Is there a way to prevent this without a power commander?

 

If this were the case though...then logically every aftermarket exhaust that is better flowing than the stock should result in a higher fuel consumption...no? And I do not think this is true - in fact I could not find a single thread or anyone complaining about a fuel consumption increase after replacing their mufflers...

 

:unsure2:


Edited by pazof, 07 February 2019 - 04:28 pm.


#7 fixitsan

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Posted 07 February 2019 - 05:12 pm

Interesting. Is there a way to prevent this without a power commander?

 

If this were the case though...then logically every aftermarket exhaust that is better flowing than the stock should result in a higher fuel consumption...no? And I do not think this is true - in fact I could not find a single thread or anyone complaining about a fuel consumption increase after replacing their mufflers...

 

:unsure2:

 

 

i think it's normal :)

 

the purpose of a 'performance' exhaust is to allow greater  performance, This generally means a lower pressure in the exhaust system....and therefore fewer CO molecules per unit volume of exhaust gas. The ECU just tries to maintain the correct fuel/air ratio. As for a Power Commander, you could fit one, but it would end up doing a similar job to the ECU at the moment, although you can tune a PC so that you use less fuel overall...but in that case it defeats the purpose of fitting a performance exhaust.

 

The way you ride is most important, My fuel consumption increased just because I liked the noise of the performance exhaust, acceleration is a big  burner of fuel, prolonged accelerations to higher than necessary RPM is just self indulgent, but provides a nice soundtrack :)

 

You could always refit the standard exhausts to make sure everything returns to normal, but also check the air filter is clean too, just in case


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#8 TKH

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Posted 07 February 2019 - 10:29 pm

I found the same when I went over to some Beowulf cans. It was only when I removed the cans due to MOT failure - too noisy apparently, that I realised it was the cans as the cause. It did't try any fuelling/mapping changes, maybe that was the problem. 



#9 chrisr

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Posted 07 February 2019 - 10:42 pm

Had Scorpions on my 04 and still got 54 mpg

The Blue One : 2004 model owned 2010-2018 much loved, much missed and now living with a man in Scotland
The Black One : 2010 Model Registered 2013 owned 2018 - present.Beowulf Cans. Renthal 755s Grip Puppies,15w fork oil,DL650 handguards,givi engine bars,led spotlights,gipro gear indicator,shortened dogbones,LeeHenty CSM kit and stainless bits,Topsellerie seat,MRA Xcreen,grip puppies.PC III (dynoed). K&N airfilter,Fenda extenda.


#10 fixitsan

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Posted 07 February 2019 - 10:48 pm

I have Scorpions, but the ECU is remapped to ignore the O2 sensor, among other things.

 

I've just realised that I mentioned the CO concentration, but it is proportional to oxygen levels. The lambda sensor measures oxygen levels, not carbon monoxide levels


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#11 pazof

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Posted 11 February 2019 - 01:03 pm

Interesting perspectives. I'll look into it. I'll also install the cats at some point and see if anything changes. Will post back results in case anyone's interested.

 

Once again thanks very much to everyone for your time.  :good:



#12 fixitsan

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Posted 11 February 2019 - 02:15 pm

Interesting perspectives. I'll look into it. I'll also install the cats at some point and see if anything changes. Will post back results in case anyone's interested.

 

Once again thanks very much to everyone for your time.  :good:

 

 

I just removed the Samios ECU and installed a standard ECU, the engine ran very well, with Scorpion exhausts and no cats, I suspect I am using a bit more fuel than with standard exhausts but it's good fun making noise :)


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