2.0 TDi140 When does fuel cons improve ?

[ean36t]

Pardon my ignorance, but what is meant by 'opening up' the engine? Seems counter intuitive that as the engine gets older, it gets more powerful...

I would live to know more.

[Roley140]

Basically, diesels have a bit of an issue running in their cylinder bores, causing prolonged high levels of internal friction together with imperfect piston ring 'bed-in'. These 2 things lead to less power/efficiency during the extended run-in period until the engine can be considered opened-up. Petrol engines dont have such an issue in this way as they start destroying themselves on day 1, having no nice diesel to lubricate the cylinder walls.

[sukrw]

Do you know what a run-in period for a diesel would be ? are we talking a few hundred miles ? a couple thousand or like 15,000 ?

I have the A3 2.0 140 TDI (10,000 miles) and on the motorway at 70mph I am only getting about 40/42mpg ... A friend who has the A4 (same engine but older with 58,000 miles) is getting easy 50+ mpg ...

Seems strange ...

Thanks.

[ean36t]

Thanks Roley140. Am looking forward to my 2.0TDI getting better!!! I've only got 2k on it at the mo. My last 1.9TDI had 30k when I traded it in, but already had 20k when I bought it... so was probably already 'ran-in'. Explains why I'm only getting 31-32mpg right now (city driving).

[Roley140]

For these VaG PD engines it is minimum 10K miles from my experience, and from general WeB consensus, before the engine is bedded in.

[Roley140]

Ive done 12K now and I'm still waiting for some decent fuel consumption. I struggle to get 43 mpg on a flat motorway run down to wales. MY old A4 TDi 130 would have done 51-52 mpg under the same circumstances. The MAF sensor change the garage did has made no difference, I'm getting a bit hacked off now, especially hearing that people with the same car are getting 50 mpg !