MPG drop since new brakes, service and matched inlets

[Gstar2006]

Hmmm it's hard to say which has resulted in my drop in MPG as they were all done round about the same time but I've dropped from easily 40mph to around 32mpg which is a fair whack.

Now the new brakes do seem to be pretty tight still even though done plenty of miles with them on. With the wheel off it's not easy to turn the disks by hand. You can do it but it's not free but I'm not sure how it should be. They're Brembo HC plain discs with Ferrodo DS Performance pads. Rears are standard plain discs and DS performance pads.

The matched inlet was a Jam Sport jobbie but was replacing RS inlets which I didn't realise until after the swap. Is there any way they RS inlets could have actually been more free flowing than the new one and gave better MPG?

And it was serviced but can't work out how this would make it worse as only really an oil change.

Ideas people?

G

 

[Jaws]

More air in = More fuel in.

 

[phantomx0_1]

40mpg in a 172. I think your computer is lying!!!!

 

[cliolou]

mine normally says 34-36 lol

 

[Gstar2006]

40mpg in a 172. I think your computer is lying!!!!

Nope work and back regularly saw over 40mpg on the trip computer before all the bits fitted.:star:

Thought about the more air = more fuel theory but other people reckon they got better MPG after their inlets fitted from Jam Sport :S

G

 

[MRBILLYUK]

mine normally says 34-36 lol

Mine normally says 26 . I'd be as happy as a pig in sh!t if iever averaged 34 -36 lol .

40mpg in a 172. I think your computer is lying!!!!

+1

 

[Pep]

No way is it lying, in the summer I easily got 36mpg on very short journeys to work.

Reading about 22mpg at the minute as i leave it running for 5 minutes in the morning to warm up/de-ice!!

Could be the brakes sticking a bit, maybe do a few high speed hard braking tests, might free it up a bit, or could be a sticking caliper?

 

[mark123]

Your wheels should spin freely - at least 1 revolution from a good spin. They certainly should not be only just turnable. Is that front or back?

I wonder if they left the shims in (on the front) that you use with the Renault pads - they can be a tight fit with after market pads.

 

[mark123]

I often get 36-38mpg on the computer - but it is lying. If I measure the fuel used and miles done it is 33-34mpg. But if you see a drop then it is still a drop no matter how much the computer lies.

 

[Gstar2006]

Pretty sure it wasn't lying as was consistant from trip to trip. Best I managed was 44mpg back from work when there was quite a bit of traffic so I was just pootling along behind them all.

I had the brakes done at Angel Works so would have expected them to know about these shims but I could be wrong. Sounds like I need to get the wheels off again and take a look but I'm not sure what I'm looking for so any help would be appreciated, pictures would be great

The brakes were sticking a little to begin with but they seem to have stopped doing that now they've been on for a couple of weeks but like I said they certainly don't spin freely but they're not tough to turn.

G

 

[mark123]

You're right I'd expect them to get the brakes right. Have you given them a call to see what they say. The pads should be free to move in the holder thing the calliper bolts on to. The shims are like little metal clips at each end of the pad, on the front this is.

Check all your breather hoses are connected up after your matched inlets.

 

[phantomx0_1]

Pretty sure it wasn't lying as was consistant from trip to trip. Best I managed was 44mpg back from work when there was quite a bit of traffic so I was just pootling along behind them all.

I had the brakes done at Angel Works so would have expected them to know about these shims but I could be wrong. Sounds like I need to get the wheels off again and take a look but I'm not sure what I'm looking for so any help would be appreciated, pictures would be great

The brakes were sticking a little to begin with but they seem to have stopped doing that now they've been on for a couple of weeks but like I said they certainly don't spin freely but they're not tough to turn.

G

Were you driving at 56mph in 5th in the slow lane!!! Max I get is 33mpg and thats driving like an old woman!!

 

[Dangerous_dave]

nothing wrong with mine from jamsport if anything i am seeing better mpgs!
prob driving with more right foot or you were getting 40mpg after a motorway run or something.

 

[Gstar2006]

Cheers for this. Will have to give them a ring to ask the question.

No more right foot being used and no I wasn't in slow lane. It's single carriageway to and from work but was probably doing 40-50 in 5th most of the way

G

 

[MRBILLYUK]

I'd be more inclined to think it was a sticking brake caliper rather than your reworked inlet manifold imo .

I had a sticking brake caliper on my 172 , failed my MOT due to it . Just greased the piston and everything was fine and it passed the MOT retest

 

[bearne1]

Same position as you, had a full home service (plugs, oil + filters) and seen mine reduce from over 38 mpg to 30 mpg with addition of matched inlet and k & n panel filter

Dan

 

[SBV116]

I have had 43 in the cup!! Woo!