loss of MPG

deaglan169

recently ive noticed a huge drop in my mpg or more my miles per tank as my car doesnt have an onboard trip computer, i travel every weekend from carlow to monaghan and back again and small trips midweek into college and into town maybe 2 miles a day midweek, it is 176km from carlow to monaghan and i used to be able to do this on 1/8th of the thank now it takes 1/4 since my last fill up (same petrol station everytime) and my dads car is diesel also he hasnt noticed any decline in his mpg so i take it diesel is ok, ive used 1/4 a tank on 133 miles this to me seems very poor considering i used to average 650ish miles a tank sometimes 700, the only thing recently that has been was a service carried out by myself (air,oil fuel filter & oil change) car is a 01 seat leon sdi with 80k on the clock, since the service the car has being going great a feeling a little more nippier than usual i know hard for a sdi to feel faster:rolleyes: but any input as to my drop in mpg would be great thanks

Anan1

Have you calculated your exact consumption by brimming the tank, driving x kms and then brimming the tank again?

deaglan169

no i havent but i could probably do this today before i head down

Anan1

Do that first - it's the only way to know exactly how much fuel the car is using. Fuel gauges are very vague anyway, and your problem might just be in the gauge.

tommmy1979

If you can confirm that it's using more fuel than it should then a diagnostic check might no be a bad idea. There's a lot of sensors which monitor air temp, air flow, coolant temp etc etc. If one's a bit screwy then it will effect your air/fuel mix and therefore your fuel economy.

Most garages will charge you an hours labour to do this even though it's a 2 minute job.

T

Also... did you buy a genuine air-filter? Air filter is one of the items i always go genuine on.

tommmy1979

deaglan169 wrote: »

since the service the car has being going great a feeling a little more nippier than usual i know hard for a sdi to feel faster:rolleyes:

You might have a case of lead foot too... amazing what damage that can do to your mpg figures

leitrim lad

that normally happens after all services,

the car seems nippier , better acceleration, ie a little harder in petrol as a result, theres your answer

nothing to worry about

deaglan169

ill keep an eye on it so maybe its just a result of the service but i have a friend with vagcom so ill give it scan also

Graham_B18C

tommmy1979 wrote: »

Also... did you buy a genuine air-filter? Air filter is one of the items i always go genuine on.

Why is that?

S-Murph

leitrim lad wrote: »

that normally happens after all services,

the car seems nippier , better acceleration, ie a little harder in petrol as a result, theres your answer

nothing to worry about

Just wondering whether servicing the car gives noticible changes in performance, or whether its more just a state of mind?

I cant think why a service would change performance that much? Maybe the spark plugs would?

leitrim lad

S-Murph wrote: »

Just wondering whether servicing the car gives noticible changes in performance, or whether its more just a state of mind?

I cant think why a service would change performance that much? Maybe the spark plugs would?

new clean plugs ignite fuel quicker,hence bad old plugs car packs up

new clean oil allows moving parts to rotate more freely ,hence old oil unchanged for years car packs up and oil goes like tar

North_West_Art

Check your tyres are wearing evenly, if they are'nt, your wheels will need alignment, you will see a marked improvement on your fuel consumption as a result

TestTransmission

Tyres underinflated?

tommmy1979

Grahamo999 wrote: »

Why is that?

Spurious filters might restrict the airflow more than a genuine one.. having said that, the difference would probably be neglibible..

Graham_B18C

tommmy1979 wrote: »

Spurious filters might restrict the airflow more than a genuine one.. having said that, the difference would probably be neglibible..

Makes sense alright, until now that be one thing I wasn't fussy about!

deaglan169

i checked my tires on way down and there was very little inflation needed, although i ahve noticed a juddering when braking in the steering wheel so possibly one of the wheels is out of alignment or not weighted correctly?