Poor MPG and lumpy tickover?

[gticupra123]

I was sat on the motorway today for about half an hour so thought I would see what MPG I could get so sat at 80mph and the best I got was 31.8mpg? I know the 8v gti's arent the most economical thing but should be better than that? As traffic slowed down I tried again but at 50mph and the best was 34.6mpg. Anyone know what could cause this?

Also Ive noticed when im sat at traffic lights sometimes the revs drop up and down between 500-1000rpm and it shakes if that makes sense. Sometimes when i dip the clutch the revs drop right down and will ocassionaly stall.

Any advice?

Thanks

Luke

 

[jcs356]

Worth checking the crankcase breather pipe - if this has a hole in it you can loose 10% of your MPG - I've had it happen twice as the pipe is in two bits hence they both can perish.

 

[gticupra123]

Worth checking the crankcase breather pipe - if this has a hole in it you can loose 10% of your MPG - I've had it happen twice as the pipe is in two bits hence they both can perish.

I know that the two pipes that sit on top on the engine with that black casing round them are perished is that the one?

 

[elcristoff]

Thank god its not just me then. My car when sat at idle and i dip the clutch abit, the car stalls. Sounds really horrible and lumpy to, but i think thats cause the exaust is blowing.

 

[Kai_1600]

Thank god its not just me then. My car when sat at idle and i dip the clutch abit, the car stalls. Sounds really horrible and lumpy to, but i think thats cause the exaust is blowing.

That sounds like the classic dirty throttle body or the sensor in your airbox being naffed up

 

[elcristoff]

So if i rip the throttle body out and give it a good old clean, it'll run through idle a bit better?

Is it hard to do? I bought a Haynes Manual, maybe that will help me

 

[edc]

You should easily show 40+ mpg on the single trip MFA when doing circa 50 mph.

 

[Fl@pper]

is it like it all the time ? or just when warm or cold etc >?

just wondering if the temp sensor is stuck in 'choke' mode or partial at least, as they get tired/worn will have an effect on running and mpg

vagcom will list the sensor reading to match it with the water temp if you wanna check it

just about to order one for mine as i swear mine runs different daily cos of it

 

[elcristoff]

I think it does it just from cold, but i haven't tested this fully yet.

What exactly is vagcom?

Sorry for the thread steal

 

[Kai_1600]

elcristoff, have a search for cleaning throttle body, loads of posts about it

 

[gticupra123]

yeah mine only does it when cold, Ive cleaned the throttle body it made abit of difference but still the same really.