Terrible mpg when car is cold

**sacha35** · 12-12-2016,02:13 PM

Hi All looking for some help or advice.

2008 Audi A4 2.0TDI CAGA engine

A few months ago I change the cambelt and water pump and followed everything to the book, but ever since then I have suffered with bad MPG when the car is cold and on short trips averaging between 20 - 30mpg, on long runs everything seams to be normal averaging between 48 - 54mpg dependent on speed.

the above figures have been reached using tank fill meathead, but what I have noticed is when looking at the did display it shows 15mpg when first started and struggles to get to 30mpg when cold where before the cambelt was changed it would read 15mpg when first started but would then quickly move up above 38mpg and above.

the above problems seem to be like too much fuel is being injected into the engine but there is no singe of smoke or rough running at all if anything the car feels better with lots of power thought the rev range. One thing I have noticed though is the temp gauge is taking some time to get up to temp, I have changed thermostat but am wondering if the problem could be with the temp sensor?

I have scanned the car and all is good without faults and captured some data which seems fine also.

Please see attached images. I hope you may be able to throw some light as to why I am having this problem and if there are any other tests I can do to find the problem

Turbo1.jpg Engine torque.jpg Air flow.jpg fuel pressure.jpg coolent.jpg

**FLAPPERJACK76** · 12-12-2016,02:21 PM

Sounds normal to me.

Sent from my SM-G900F using Tapatalk

**zollaf** · 12-12-2016,02:23 PM

maybem just maybe, you have the timing slightly out..

**Crasher** · 12-12-2016,02:26 PM

What did you lock the cam and crank with?

**sacha35** · 12-12-2016,02:37 PM

Originally Posted by Crasher

What did you lock the cam and crank with?

Hi Crasher & Zollaf

I used the locking tools as to Elsawin and set as instructed.

I have logged with hot engine.

IDE00021 Engine speed 836 /min
IDE00405 Crankshaft speed (RPM) 839.5 /min
IDE00406 Camshaft speed (RPM) 418.3 /min
ENG106252 Synchronous angle 0.00 °

from what I can see with Synchronous angle the timing looks to be spot on.

This one has got me baffled.

**Deanoc** · 12-12-2016,02:50 PM

Did you own the car last winter? My old 2.0TDI easily dropped 10mpg in winter on a 15 mile trip i did a fair bit

Sent from my SM-G935F using Tapatalk

**sacha35** · 12-12-2016,02:54 PM

Had the car from new, There is a problem the car is drinking fuel when cold and dong short trips or stuck in traffic.

**FLAPPERJACK76** · 12-12-2016,05:11 PM

My usual weekly commute in my 1.9 pd is £30. Last week same commute £45. I brim the tank every Sunday and that's how I know. It's down to the recent cold spell.

Sent from my SM-G900F using Tapatalk

**Crasher** · 12-12-2016,07:46 PM

Check the actual coolant temp in measuring blocks when you are cruising at a steady speed, don't take any notice of the dash display, look at in in engine 01.

**Rob69** · 12-12-2016,08:12 PM

Don't those CR engines have two stats in the system ??
My 1.9 PD engine mpg has tailed off recently and a check with VCDS showed temp at low 70's even though dash says 90' and stat set point is 85'. stat change coming up after christmas to hopefully improve mpg, all else looked ok on my engine.