Crazy mileage drop- HELP PLEASE!!!

[123rado]

Hi all,

Car is 2.0L DTi Y20DTH Diesel engine with over 100K on the clock.

As some of you are aware, I did service on car last 2-3weeks or so. Well before the service I observed my mileage was dropping and I couldn't figure out why.

I usually get an average of 400-420miles on full tank of diesel driving round town irrespective of the time of the year. More than 500miles when I drove to london sometime early this year.

Now I started getting about 380miles on full tank about 2months ago. Got the tyres checked and was told they were ok. Was advised that probably car is needing service (it's been 7months and over 7K miles since last service anyway).

So I did the service (changed fuel, oil, pollen, air filters, changed the engine oil, cleaned the EGR and turbo booster) and got another tankful of diesel. The fuel gauge needle is now sitting on the second red line and fuel light has come on and the mileage is about 360miles which means the initial problem causing the drop in mileage is still there and probably getting worse.

Can someone suggest to me what the problem is with this car bearing in mind that my driving pattern has not changed and I have had the car over 3 winters without this sort of issue.

Thanks for reading through and sorry for the long post but need to put everything in perspective. Thanks.

[WilliamLX]

Is there any sign of fluids leaking from the car when parked? MAy be time to get it professionally checked over at 100K all sorts of bits and bobs are going to be pretty worn, you may have a leak in the fuel lines??

[Ian-Highlander]

Also worth checking all the hoses under the bonnet (especially ones to do with the turbo) for splits.

[danny1992]

Wel i bought my vectra 2.0TDI and around town i get about 360 miles to full tank since i have had the car. Last time i filled up i only got 260 miles im not sure why this is but its only happended once so maybe becuase i filled up at a different place. But Since i have had the car i have only had 380 tops to a full tank.

[123rado]

Also worth checking all the hoses under the bonnet (especially ones to do with the turbo) for splits.

Thanks. Turbo hose looks ok and last time I had a turbo hose split, car was dragging and EM/catalytic converter light were on so don't think it's that.

[123rado]

Is there any sign of fluids leaking from the car when parked? MAy be time to get it professionally checked over at 100K all sorts of bits and bobs are going to be pretty worn, you may have a leak in the fuel lines??

Thanks but there is no sign of leakage anywhere. I have tried checking all the lines and everything seem ok. Need to know what could likely be causing this and if I can fix it before taking it to the professionals.

[123rado]

Wel i bought my vectra 2.0TDI and around town i get about 360 miles to full tank since i have had the car. Last time i filled up i only got 260 miles im not sure why this is but its only happended once so maybe becuase i filled up at a different place. But Since i have had the car i have only had 380 tops to a full tank.

Thanks for sharing this information. I have always filled up my tank at one particular place except I am not within town (which is occassional). If I was getting 380miles on full tank all the while I have had the car, believe me, I won't be worried.

[the-wizard]

Try some fuel cleaner in with some bp ultimate or shell v power!, also i find this time of the year my mpg will drop slightly due to the cold!, the difference in instant mpg between winter & summer is vast!. on the same stretch of duel carrigeway with cruise on at 60mph - summer = 90's-120mpg, winter = 70-90mpg.

[123rado]

Try some fuel cleaner in with some bp ultimate or shell v power!, also i find this time of the year my mpg will drop slightly due to the cold!, the difference in instant mpg between winter & summer is vast!. on the same stretch of duel carrigeway with cruise on at 60mph - summer = 90's-120mpg, winter = 70-90mpg.

Ok thanks. Will try out the redex fuel cleaner with shell v power to see if it makes any difference.

[123rado]

Any further suggestions are welcomed please. Need to get to the route of this problem. Thanks