Noticable drop in MPG after nearly 4 years ownership - Edition 30

[GTImike]

Hello All,

Just after a bit of a heads up with my Stage 2 Edition 30. I've owned it for a long while and week in, week out it has always returned the same MPG but since the cold spell last year the MPG has dropped by at least 10%. The car still runs fine and pulls like a train just as it always has. It has a Rev G DV and that seems to be in full operational condition but I've got a feeling it might be something to do with the PCV valve.

I've done the usual telltale test of pulling the dipstick while the engine is idling and the tickover goes very rough, which I understand means the PCV is working? There is a smell of oil from time to time and signs of discharge around the PCV though which makes me think something isn't quite right with it. Just wondering if any one might be able to shed light on other known causes on this MPG drop. I'm possibly going to buy a PCV bypass kit but wanted to know if this has big downsides apart from needing a catch can.

Thanks,

Mike

[Orc]

Needs a decoke by the sounds buddy

[GTImike]

Cheers for the reply mate,

As in, one of those Terraclean type engine services or a decoke of the PCV?

[Orc]

Yeah a terraclean,there ok but like a few others if your able to do it yourself then this item number in eBay is much better. 181082554502

[GrayMK5GTI]

Terraclean may take a bit of carbon off the inlet valves, but your better off having the inlet manifold removed and the valves cleaned properly. Will make a massive difference 

[Carpy25]

may be nothing more than the brakes dragging a little , would push the MPG down a lot , check for heat in one wheel more than the others after a run

Rob

[GrayMK5GTI]

Tyre pressures too

[Matthewsimone]

may be nothing more than the brakes dragging a little , would push the MPG down a lot , check for heat in one wheel more than the others after a run

Rob

Yep i had a rear caliper binding slightly few months back
Fitted a new one and average mpg went back up by about 4-5mpg 
Now hit 41mpg on way into work instead of around 36

[Hurdy]

Tyre pressures too

Or even just new/different tyres with a higher roll resistance. 

[GrayMK5GTI]

Tyre pressures too

Or even just new/different tyres with a higher roll resistance. 

Fair point. I noticed MPG drop a bit after fitting Pilot Supersports from GY efficient grip

[GTImike]

Thanks for the replies guys, I've been away for a few days.

Something else has just struck me since posting, the car is taking marginally longer to start up sometimes. I'm only talking a second or so difference but its always been instantaneous until i noticed the mpg drop then I got thinking...

I don't think the spark plugs have been changed for 2 years or more. Its having a full major service this month so they will be getting changed then.

Its definitely not tyre pressures or binding calipers, I've had a couple of BMW's that were prone to that. I always keep my eye on levels and pressures. Its been run on the same brand/type of tyre Goodyear Eagles for 3 years or more, however all 4 were changed last November.....

And I can't actually see it being a carbon build up, the car has only done 44k miles and I've driven it for 40k of those, I'm not the sort of person who allows carbon to build up. The car doesn't sit in traffic much at all.

Would anyone recommend a different spark plug for a stage 2 eddy by the way?

[lukemk5gti]

may be nothing more than the brakes dragging a little , would push the MPG down a lot , check for heat in one wheel more than the others after a run

Rob

Yep i had a rear caliper binding slightly few months back
Fitted a new one and average mpg went back up by about 4-5mpg 
Now hit 41mpg on way into work instead of around 36

41mpg? How long is your drive? The max I've ever gotten was 41.2mpg driving at 100km/hr all motorway with cruise control at exactly 100km/hr

I wonder if something is a miss on mine

[Matthewsimone]

may be nothing more than the brakes dragging a little , would push the MPG down a lot , check for heat in one wheel more than the others after a run

Rob

Yep i had a rear caliper binding slightly few months back
Fitted a new one and average mpg went back up by about 4-5mpg 
Now hit 41mpg on way into work instead of around 36

41mpg? How long is your drive? The max I've ever gotten was 41.2mpg driving at 100km/hr all motorway with cruise control at exactly 100km/hr

I wonder if something is a miss on mine

My work journey is around 7-8 miles depending on route choice but mostly flat and dual carriageway all the way except a 1 mile 30mph bit of straight road slightly down hill
A just set cruise to around 6ph and trundle into work most days, (not rushing into work  ) best ive seen is 44.1mpg on that journey

Drops quite considerably on the journey home though as foot down in the rat race so usually only around 27mpg
 

[#ed30]

may be nothing more than the brakes dragging a little , would push the MPG down a lot , check for heat in one wheel more than the others after a run

Rob

as i found out only last week - seized rear caliper and a drop of mpg in the region of 20%! now i can get nearly 38mpg on the motorway journey to work 

[Eccie]

Mike I would think its the pram and paraphernalia in the boot & two kids in the back  - all that extra weight