Been driving my (new) 2005 vrs for a week now and not getting the fuel economy i was hoping for. Maybe i was expecting too much but it doesn't seem to be much higher than my old 1.2 petrol.

Just did a 25 mile run mixture of a roads and country lanes steady speed not exceeding 60 mph and mostly gentle acceleration.

It returned 38mpg. If I drive it on a short <10 mile run and drive it hard then it returns 35mpg which is what I would expect for that style of driving.

I cant feel any other issues with the car it pulls well and no visible smoke even under hard acceleration, EGR has been cleaned and elephant hose mod done in case that matters.

Could I be looking at the MAF being an issue? I don't know what the performance 'should' be like as coming from a 1.2 fabia its a hell of a lot quicker and it seems to go like hell in 2nd 3rd and 4th.

Anyone with any advice as to what to check?

I have scanned it with VCDS and it comes up with a Camshaft position sensor error which doesn't seem to cause any starting issues or poor running.

AFAIK its not mapped or anything

@clarendon462 - OK, it's only a 110 (but therefore shorter geared), but it's an Octy so heavier, and I'd be a bit unhappy with economy that poor.

Difficult to say or not if you have a problem without a full brim to brim calculation. 

 

That said, my first port of call would be to check the rear brakes aren't binding. 

On a long 60 mile gentle cruise at around 50-60mph with a few hard accelerations testing it out it returned 44mpg. That was picking up the car initially and I noticed a fair bit of black smoke on hard acceleration. This soon cleared after giving it a good drive as the previous owner only used it for town driving and had an insurance box thingy fitted so doubt it was ever driven hard.

I will check the rear brakes but they dont seem to be making any noises or excessively hot after driving. Surely I would smell the cooking brakes after a drive if they were binding?

I didn't  

1 hour ago, jars said:

I didn't  

Just jacked up the rear and the wheels spin freely although you can hear the pads touching slightly. I can push the wheel round and it spins for quite a while so cant see how this would affect fuel economy although i may be wrong.

3 hours ago, clarendon462 said:

I have scanned it with VCDS and it comes up with a Camshaft position sensor error which doesn't seem to cause any starting issues or poor running.

AFAIK its not mapped or anything

 

I strongly suspect the cambelt timing is out of spec.

 

Bad timing will give a position sensor code and poor fuel economy, performance is probably down as well but you wouldn't know that since you're a new owner.

Just now, sepulchrave said:

 

I strongly suspect the cambelt timing is out of spec.

 

Bad timing will give a position sensor code and poor fuel economy, performance is probably down as well but you wouldn't know that since you're a new owner.

how do i check the timing??

the belt was replaced in previous owners ownership last july

You need to lock the cam in place and look at the crank pulley position to see if the locking device will slide into place. if not then it's 'no bueno', there is also a measuring block in VCDS for torsion value, but if it's way out enough to throw the error that might not be available.

 

Edit: You can use a drill bit instead of a locking pin, 6 or 7 mm, I can't remember which.

Edited 6 July, 20178 yr by sepulchrave

I've just plugged in the vcds and checked block 4 it comes up with this on idle and goes to 1.17 with air con on and revs at around 2k

 

 

Edited 9 January, 20188 yr by clarendon462

That's not brilliant, try and get it nearer to zero if you can but we can look elsewhere for the fuel economy culprit, the MAF is next on the hit list, again VCDS can provide useful info about MAF accuracy.

4 minutes ago, sepulchrave said:

That's not brilliant, try and get it nearer to zero if you can but we can look elsewhere for the fuel economy culprit, the MAF is next on the hit list, again VCDS can provide useful info about MAF accuracy.

Ok, how should I go about measuring the MAF accuracy with VCDS?

Im new to using the software so don't know much about its functions

1 hour ago, clarendon462 said:

Ok, how should I go about measuring the MAF accuracy with VCDS?

Im new to using the software so don't know much about its functions

 

There's a thread somewhere about it, a crude test would be to just unplug the MAF and see if it drives the same with the same poor economy.

If you have a camshaft position sensor fault code why chase other things if you have not changed the cam sensor?

 

They are not expensive and not difficult to change, if you have VCDS Lite you could then set up the cam timing spot on.

 

I have had my VRS for years and thought it was all running fine, I finally got around to getting VCDS Lite and it had a camshaft position sensor fault code, I replaced the sensor and set up the cam timing, it improved the engine performance across the board, without VCDS I would still be driving around thinking all was ok.

 

So my advice would be to replace the cam sensor, set up the cam timing to as close to zero as you can get and then do a full tank to full tank mpg check (don't rely on the onboard computer mpg), if you still have issues then investigate more.

@sepulchrave-will try that tomorrow then

@duck- that might be something to investigate then. Im guessing I need to do some reading on how to do iit

Edited 6 July, 20178 yr by clarendon462

Tried disconnecting the maf and the car was really sluggish and struggled to do 70mph.

Guessing the MAF is working then but maybe still not right?

Thats quite low fella. I struggle to get less than 51mpg.

 Torsion timing checking/adjusting, worth a read:-

http://www.myturbodiesel.com/wiki/camshaft-timing-torsion-value-adjustment-on-vw-and-audi-pd-tdi-engines/

Hopefully the new cam position sensor is coming tomorrow so will get timing done.

Just got 44 mpg on a 70 mile run at steady cruising speed on a roads in medium traffic. Not particularly good I would say.

Have another priority now though the drivers window reg has just broken :( Only replaced 1 month ago by previous owner

 

I adjusted the timing today from -1.7 to 0.0 and went for a short drive round town no more than 50 mph and got 47 mpg. Big improvement from what i was getting before hopefully will be more on a longer run.

Seems to be more responsive from low revs as well.

Can I adjust it any further to get even better running? whats the recommended amount for the fabia as the tdi page i looked at mentioned different values for the bora and the passat

6 minutes ago, clarendon462 said:

I adjusted the timing today from -1.7 to 0.0 and went for a short drive round town no more than 50 mph and got 47 mpg. Big improvement from what i was getting before hopefully will be more on a longer run.

Seems to be more responsive from low revs as well.

Can I adjust it any further to get even better running? whats the recommended amount for the fabia as the tdi page i looked at mentioned different values for the bora and the passat

 

You can't get any better than zero.

 

Question: Ask yourself why two different body styles with identical drivetrains need different timing setups.

 

Answer: They don't.

 

Beware internet muppetry.

Just now, sepulchrave said:

 

You can't get any better than zero.

 

Question: Ask yourself why two different body styles with identical drivetrains need different timing setups.

 

Answer: They don't.

 

Beware internet muppetry.

I did wonder, it was on the link provided by @KeithCheetham a few posts ago 

I bought a replacement cam sensor however it doesn't fit due to the cable being too short. Going to get another and try it in case the one I have is faulty

1 minute ago, clarendon462 said:

I did wonder, it was on the link provided by @KeithCheetham a few posts ago 

I bought a replacement cam sensor however it doesn't fit due to the cable being too short. Going to get another and try it in case the one I have is faulty

 

Try clearing the code and see if it goes away now you have the timing spot-on.

1 hour ago, clarendon462 said:

I did wonder, it was on the link provided by @KeithCheetham a few posts ago 

I bought a replacement cam sensor however it doesn't fit due to the cable being too short. Going to get another and try it in case the one I have is faulty

 Sepulchrave is correct with his statement on 0.0, the link was just to instruct on how the correction is carried out - sorry for any confusion created. When I did mine I seem to remember there being a value reading difference between a cold and warm engine - unsure why but someone may be able to confirm if this is to be expected.

It was ok I just wondered for the reasons behind the values being different on the link.

Is it worth me cleaning my MAF as an extra step to improving the running of the engine?