1.9tdi limp mode and bad mpg

[metterzrocks]

Hi all, new to here. 1.9tdi recently went into limp mode and mpg is deteriorating. I know little about cars but a pal of mine cleaned egr valve, checked hoses etc and its not done it since. However, mpg is not getting better, its simply getting worse. Not reset the on board display since i got the car 3 months ago when it showed an average of 40+ mpg, but it drops 0.1 roughly every 2 days. Its currently at 32.1 mpg, this seems very bad doesnt it? Anything obvious to check?

[technics100]

Is it the 100 or 130 bhp?  my 100bhp returns 48 over every tank.. your's sounds bad.. dodgy maf maybe?

[Gaz]

.. dodgy maf maybe?

 

Seconded - my 110 Passat was chugging and felt like the turbo had been nicked.  The Air Mass Meter was the problem and a new one brought the power and mpg straight back up.

 

This was a good few years ago.  I'm sure I've read since that they sometimes don't throw up any fault codes either.

 

Gaz

[metterzrocks]

yeah its the 130bhp. had it run through the vag-com and its not showing any faults. did however swap the maf with my pals from his audi a6, run it for a day and there was no difference though? reading a bit more into it today though and im hearing it could be a culmination of the following:

 

1. its an automatic

2. ive had the air con on constantly (i know)

3. i only drive 3 miles to work so it never warms up

4. all city centre roads

 

plenty other people saying this sort of scenario to expect 30mpg so maybe its not that unusual?

[jimbof]

30mpg is all you will get for that run, sorry.

Trip average doesn't get to 40mpg on my 1.9 auto until I've covered around 15 miles in the morning, at a steady pace (first few miles of traffic, then dual carriageway).

My run is 55 miles each way though, so over a tank I average around 46-7mpg.  

[metterzrocks]

thanks jimbof, if anything its a relief to here that. id rather it be that than an expensive fix, cheers pal

[Danny 57]

Those short journey's are not going to be kind to a diesel unless you are also making some longer trips as well.

[jimbof]

They just aren't very efficient until warmed up, and these engines take quite a long time to warm up.  And on these it isn't just the coolant - there are 9 litres of automatic fluid to contend with... 

 

If I get a really good long motorway run and take it steady I can coax it up to 51/52mpg.  But just driving round town I'm lucky to get above 30-32mpg.  Glad I hardly need to drive it round town!

 

The gearbox really doesn't help - it holds on to the gears a bit too long to be economical - i.e. if you are only doing 30, you'll probably be stuck in 3rd gear.  If you take it up to 35-37 it will change up to 4th, and then it will stay in 4th until you get down to around 29-30mph.  You can get a bit more economy by getting it up into 4th and then backing off, but it will be marginal I think on your runs.

 

Think of the upsides - if you have a 6 mile commute, even at 25mpg you're still looking at less than £10 worth of diesel a week.  I average 45-47mpg - but that is sticking £80 of diesel in each and every week... I'd take 25mpg and be happy! :-p lol

[Cown]

With that small trip to work, no wonder it's not working. 

[ronatholl]

Those short journey's are not going to be kind to a diesel unless you are also making some longer trips as well.

yes i only do short journeys i think thats why the diesel particle light is coming on

[jimbof]

If you only do short journeys you should never buy a diesel with a DPF... it _will_ block, you might get oil level rising in your sump from diesel going into the oil (not sure if this affects VW/Skoda, but definitely a Peugeot / Mazda issue), and it will never be as economical (cost wise) as even a petrol, by the time you factor the premium you paid for the car and the extra maintenance / repair costs.