Increased Fuel Comsumption SInce installing standard mufflers back on

[warnzie85]

Don't know if you might of read my post a few days...long story short, guy ran up back of my NEW sv6, no real damage rear muffler a tiny bit bent at tip, took to exhaust shop and guy took me for a absolute ride - hind sight would of been grate!!!! and gave me straight through pipes which are way to loud especially since my wife gave me the news of a child on the way so quieter the better at this stage. So i fixed up standard muffler and put them back on....mmmm quietness Since doing that my fuel eco has gone up into the 11lt avg doing same driving route as usual when it was sitting on the 10lt mark, so for no real reason it has gone up???

Is this because of the ECU relearning things?? or is it a exhaust leak from mufflers?? the bolts are tight trust me

I know it may not seem like much but when you have constantly sat on 10lt for who knows how long doing same trip day in day out over 3500kms and get in car after changing mufflers and jumps to 11lt and over for no reason you start to wonder??

[HussySV6]

Well it does seem right, as when your purchasing an exhaust it usualy says that u get better throttle response, more power and IMPROVED FUEL ECONOMEY. I wouldnt have any clue to as why? but maybe somthing to do with less ristriction, MORE FLOW?
Coz at the end of the day thats basically what an exhaust does, gives more flow?

So i wouldnt say theres anything wrong with the mufflers u put on or whatever, seams perfectly normal

Im no expert so if im wrong please correct me someone.


BTW your sv6 is the SIDI yes? i thought it should do 10L ?

[warnzie85]

Yes it is the SIDI...I should clarify yes since new and before installing the straight through pipes i was getting 10lt avg, with them on slightly better at 9.7ltavg but since putting originals back on bang straight up to 11lt avg for no reason????

[HussySV6]

Im not sure then buddy sorry! but i would guess that because the exhaust had better flowing and now going to ristriction maybe it isnt use to it, give it a day or 2? But yeah no idea man sorry

[Allistaire]

Mate try taking the battery off for a few minutes and reset the ecu and then give it a couple of days for it to re adjust and it should come back down again. Also have you checked the air filter

[warnzie85]

yeah it a 2500km old K&N air filter so all good there. I might wait till i fill up again and see if it has adjusted itself?

[Not_An_Abba_Fan]

Did the muffler change and the filter change happen at the same time? Sometimes oil from the K&N can contaminate the sensors and give you bad economy.

How badly was the muffler damaged? It could have broken a pipe internally and now is more restrictive.

[UFO]

How badly was the muffler damaged? It could have broken a pipe internally and now is more restrictive.

^ Very plausible, good point ^

All it would take is an internal baffle to be out of place a little bit by the impact, and that could definitely cause more restrictive air flow. The damage wouldnt be visible from the outside.

The fact that you've noticed less fuel economy straight away can easily be confirmed by putting the other ones back on. 1L difference is substantial in the long run.
Got a mate you can borrow mufflers from to test different stock ones?
Otherwise try and pick up a stock set via ebay, there would be plenty of people getting rid of stock units because of aftermarket installs.

[Jesterarts]

Couple questions:

1. Did the disconnect the battery when they installed the exhaust? This could account for the sudden increase. I find that just after filling up and resetting trip comp my fuel average is high and after driving for a while it gets better. So if they disconnected the battery the trip comp would have reset?

2. Now that your exhaust is making more noise, is it potentially your foot giving the command to make the noise more often that is affecting your average fule usage?

Just things to consider.

Hope it helps a bit.

[warnzie85]

thanks for everyone's input, Im only shy of 3/4 of this tank finishing so i will wait and see how i go next fill up. This current tank saw me replace the straight through pipes with originals so maybe it was adjusting itself early in the tank (ie first 1/4) hence the higher consumption avg now at the end of the tank. If i don't go back down to my 10ish avg since new I think the post regarding dislodged baffle maybe the culprit??? Their is no other explaination. Other than that i could get Lukeys / redbacks put in the straight through pipes between flange point and tips???? Do you think it would get rid of the drone????

[UFO]

Other than that i could get Lukeys / redbacks put in the straight through pipes between flange point and tips???? Do you think it would get rid of the drone????

Might. Only way to get rid of cabin drone is to either muffler up or insulate. Trial and error is this instance mate, no real short cuts.

[warnzie85]

Is it worth taking out the "mid section" i think its call where it's 2inch and replacing with 2.25? Will this quieten it down?