Poor MPG and bad smell

[Carbon VW]

Hello! Driving to work this morning I noticed the car seemed a little off. Maybe a slight judder here and there and when I checked the driving data my mpg was poor. 33mpg where I would usually always get 40MPG on my commute. Popped the hood when got to work and got a slight burning smell but couldn’t see anything wrong. Scanned it in car park after work and no codes on OBDeleven. Hmm  on the way home mpg was again bad and car just feels off. Slight bad smell coming though the vents when I stopped at junctions etc. anyone any ideas??. I’m on original coil packs but did change spark plugs once.

[madstaff]

GPF cleaning cycle, 4th post down??

https://www.golfgtiforum.co.uk/index.php?topic=286021.0

[Carbon VW]

Nah it’s a 2013 gti. It doesn’t have a GPF

[GKR47]

The current cold weather will have an adverse effect on mpg.

[Carbon VW]

Not that much. I’ve had the car since new and I know when it’s not right. And it’s not right

[bogwoppit]

As it's been mapped to stage1, would the ECU still detect a catalytic converter fault?
I'm wondering if it's partially blocked or breaking up.

[madstaff]

I would try a scan with VCDS if possible??

Perhaps look at the data for the lambda sensors.

[Carbon VW]

Update. I took off the coil packs(nightmare as they were welded onto the plugs) and pulled the plugs. All looked ok so I replaced. Took it out then for a hard spin, seemed ok for first 5 mins then got bad smell again and the stuttering was then felt again, particularly under braking. When I got back to the garage the drivers side front brakes were billowing smoke. The alloy itself was red hot. Front brakes and pads (Brembo) were professionally fitted about 3,000km ago and are as new. I assume the calliper or something is causing the brakes to stick. This would also explain the poor mpg on my commute this morning. Any ideas on how to approach this? The passenger side and rear brakes are fine and cool. And yes the slider pins were lubed up when fitted.
Thanks for the replies so far. Brakes aren’t my strong point 

[madstaff]

Sounds like the piston is seized in the caliper or maybe the pads are seized in the carriers.

Piston and seal kits are available I would imagine from TPS or somewhere like this https://www.brakecalipersolutions.co.uk/product/fit-vw-golf-mk7-2012-2014-front-axle-brake-caliper-seal-repair-kit-bsk5747/

Just depends on what the pistons like, if the chrome has started to peel they're knacked.

Normally what I find is that someone has torn/ripped the dust seal which allows water ingress which then creates rust on the lip between the actual fluid seal and dust seal causing the piston to stick.

If your not confident in working on your calipers though, best leave it to someone who does.

Or just get yours remanufactured, and in a choice of colour too. https://www.biggred.co.uk/caliper

Or

https://www.ebay.co.uk/itm/115335577726?fits=Car+Make%3AVW%7CCars+Type%3A2.0+GTI%7CPlat_Gen%3AMK+VII%7CCars+Year%3A2013%7CModel%3AGolf%7CVariant%3APetrol+Hatch%7CEngine%3A1984cc+162KW+220HP+CHHB%3BCNTC%3BCXCB%3BCXDA%7CBodyStyle%3AFWD+VII+5G1%2CBE1%2CBE2%2CBQ1&hash=item1ada89407e:g:EU0AAOSwbm9iUaGx

[Carbon VW]

Thanks Madstaff. Have it booked in to my mechanic to confirm the Caliper is the problem. He did say it’s rare for them to fail, especially in the fronts. Will post back when diagnosed/sorted.