TDI Power Drop and Fuel Consumption Issues

[Goes4Eyes]

This is my first post and I cannot see anyone else having this problem so I hope I'm not wasting people's time having missed a similar issue in another forum on SC.

My 04 150PD Cupra has been running slightly slowly for the last few months and fuel consumption has dropped. On a cold morning I can get it as low as 6mpg and my 10 mile trip to work pulls 30mpg average (it used to be 45-50). A recent 'work done' history: I had glow loom errors coming up on VAGCOM so fitted a new one. I also fitted a new MAF. There's a new Pipercross airfilter and I recently changed the oil, put injector cleaner in, had new glow plugs about 3k ago and finally new brakes all round. VAGCOM isn't bringing up any other errors. The cars at 95k and the only problem I've had with it in the last 60k was a worn gearbox bush. The lamba sensor tests fine. Anyone got any clue what it could be?

Your help would be appreciated. The copy of VAGCOM is not a full copy - in case you were wondering.

 

[UncleFester]

95k and what kind of driving, if it's been mostly short journeys there is a good chance the EGR and intake are utterly bunged up with crud. I'd also be checking the operation of the VNT vanes in the turbo too.

You can cycle the vanes using a free version of vagcom

http://www.seatcupra.net/forums/showthread.php?t=94652

 

[Goes4Eyes]

Thanks for getting back so quickly buddy. Yes - my drive to work in morning is 7-10 miles. I do do long distance (2.5k last summer around Europe) but mostly it's the short work run. I'll have a look at the form link you've posted and let you know how I get on. Thanks again.

 

[UncleFester]

Thanks for getting back so quickly buddy. Yes - my drive to work in morning is 7-10 miles. I do do long distance (2.5k last summer around Europe) but mostly it's the short work run. I'll have a look at the form link you've posted and let you know how I get on. Thanks again.

There's always the italian tune up option - take it out and give it a good run through the gears, accelerator all the way down etc etc - up a long hill would be even better. I get the impression that yours is driven with care and consideration mosf of the time due to traffic.

Mine on the other hand gets regularly driven hard and at 56k miles, there is no soot / crud in either the EGR or the Intake although I did have to have the turbo replaced

The above will only clear sticky vanes, it won't undo the problem of a blocked EGR / intake - removal and manually cleaning out will be the only option if that's the problem. As ever there are plenty of threads on here that relate to what to clean and how to clean it. Alternatively take it to a garage and let them get bloody knuckles removing stubborn stuff

Scroll down to the bottom of this page http://www.stealthtdi.com/TDI-Problems.html and you'll see what a blocked intake looks like, however this is very dependant on driving style and where you drive

 

[Goes4Eyes]

It's not driven gently - I live in the west midlands and there's no traffic. Morning's is a gentle drive due to the engine being cold but I do give it a hard time whenever the roads are up to it (LingLong 235's on the back - long life and great in the dry - downright dangerous in the wet!).

I'm just charging my lappy and I'll go out and try your vanes suggestion. If it doesn't work I've spoken to my mechanic and he'll have a look at the EGR/intake (he's cheap cos I'm doing his website)

 

[UncleFester]

It's not driven gently - I live in the west midlands and there's no traffic. Morning's is a gentle drive due to the engine being cold but I do give it a hard time whenever the roads are up to it (LingLong 235's on the back - long life and great in the dry - downright dangerous in the wet!).

I'm just charging my lappy and I'll go out and try your vanes suggestion. If it doesn't work I've spoken to my mechanic and he'll have a look at the EGR/intake (he's cheap cos I'm doing his website)

I would be very surprised if it was something major - if your turbo was packing up you would have heard odd noises by now. Other problem you might have is a split actuator hose off the turbo to the N75 but you won't see that unless you have the undertray off - might be worth asking your mechanic to check all the vaccuum connections / lines too.

Out of interest, when do you change gear when you give it a run, do you take it right up to and past 4krpm?

 

[Goes4Eyes]

I used to when it was tuned as the boost lasted long after 4k but now I change up just before 4. In case you were wondering - had it de-tuned because I 'thought' it caused boosting problems. Turns out the top left turbo hose was boosting and rubbing itself against the brake fluid reservoir sensor - but a whopping great hole in it. Replaced it but never got round to retuning (any company recommendations would be welcome - I used SP tuning).

 

[UncleFester]

I used to when it was tuned as the boost lasted long after 4k but now I change up just before 4. In case you were wondering - had it de-tuned because I 'thought' it caused boosting problems. Turns out the top left turbo hose was boosting and rubbing itself against the brake fluid reservoir sensor - but a whopping great hole in it. Replaced it but never got round to retuning (any company recommendations would be welcome - I used SP tuning).

Depends on where you are but anything from Revo/Jabba/JBS/AMD/Ptorque for a stage 1 map would be more than fine and shouldn't cost the earth.

95k on a standard turbo that's been mapped once before and will then be mapped again - i think i would request a conservative map OR ....... get it on an RR to see what the actual power is.