2.0 8v - increased fuel consumption.

[DPJ]

My fuel consumption has mysteriously increased. I'm only getting about 27mpg at a steady 80 on the motorway and average consuption is around 27 too. Over 80 and it drops rapidly.

Nothing showing on vag-com.
I've checked the breather hose thoroughly, no splits.
Plugs look fine.
It starts fine and there are no other obvious signs of a problem. However, when first started cold (outside temp 10 degrees) the idle isn't much above 1000 rpm - I'd expect it to be higher.
I fitted a new air temp sensor to the airbox a while ago as it didn't have one (and a fault code went).

I'm going to look at the throttle body next and change the Coolant Temperature Sensor. (I don't think it's the throttle body)

Any other suggestions please?

 

[Feel]

Might be daft, but have you checked the fuel tank for leaks?

 

[DPJ]

Might be daft, but have you checked the fuel tank for leaks?

No Phil, I'm just going off the MFA display - as I can see 'instantaneous' consumption, it's pretty obvious it's going into the engine.

(No petrol smell outside - unlike the carbon-canister-less Leon )

 

[wilz]

Coolant Temperature Sensor, i had to change that along woth my lamba sensor for the poor fuel consumption ( the coolant temp sensor was the culprit so the garage said)

 

[jenk]

Yep, coolant temp sensor is always a good one to change.

The 8v is a great engine but when it comes to finding an electrical/sensor problem it can be a nightmare.

....they do idle quite low on warm up from memory

 

[Saul]

check the fuel hoses into the engine bay and to the fuel rail, have a habit of perishing and leaking when cold (seal up when warm)

cant remember if they have a map sensor on the 8v?

 

[DPJ]

check the fuel hoses into the engine bay and to the fuel rail, have a habit of perishing and leaking when cold (seal up when warm)

cant remember if they have a map sensor on the 8v?

Cheers Saul, I'll have a good look at them too. No map sensor.

I've ordered a new coolant temperature sensor today too.

 

[orangemuffin]

do you have a boost valve. Mine dropped on the 8v after i installed one ?

 

[DPJ]

do you have a boost valve. Mine dropped on the 8v after i installed one ?

No, it's standard.

What's a boost valve?

 

[orangemuffin]

An FSE Boost Valve...

There like an uprated fuel managment system....increases fuel delivery into the engine...it has a cap on the top you can adjust. it made my 8v alot more responsive.

 

[Cupra Kid]

they do hit just 1000 on warm up really, drops to around 850 when warmed up.

I'm getting high 30's on mine thanks to the loss in temperature (was 40's) so i guess yours should do that if going well.

 

[DPJ]

Thanks for the replies everyone. I'll report back after swapping the coolant temperature sensor.

 

[m0rk]

can you log the MAF?

 

[DPJ]

can you log the MAF?

Do bears sh1t in woods?

What sort of reading should I be expecting?

 

[m0rk]

no idea something

 

[DPJ]

There is a limiter, isn't there?

 

[jenk]

Rev limiter? If I rememember correctly it trys to throw you out the windscreen?

 

[DPJ]

I'll take some sandwiches to eat during the power run.

(I should have time to tidy up before I get to the limiter)

 

[Damoegan]

I'll take some sandwiches to eat during the power run.

(I should have time to tidy up before I get to the limiter)

 

[DPJ]

can you log the MAF?

Do bears sh1t in woods?

No, it seems there isn't a measuring block that shows the MAF reading. There aren't many measuring blocks.....