I have attached info on my efforts to find the fault with my turbo system. Can anyone with experience direct me from this information?

 

Many thanks

vagcom.pdf

Edited 13 March, 201610 yr by freddyuk

If recycling the ignition puts the turbo back to normal each time the turbo does not appear to be boosting I would guess the vanes are sticking. If you search on Briskoda you will find various methods of cleaning the vanes from using Mr Muscle to removal and cleaning. It's a common problem on the VAG 1.9 TDI. 

No, recycling the ignition does not reset the turbo each time.

Today I started with the EGR valve and blocked it off. Instant result the turbo was working and I had full boost all day doing various short trips but using plenty of throttle. I thought this was the problem and the cure. However I then reattached the VCDS to get some readings and the fault codes had all disappeared however when I drove off I felt the power was down again and the turbo was partially working so it seemed the VCDS had somehow switched on limp again?? I have much more power and freely revs but the turbo has gone again. Even without turbo the power is up.

The code it threw up now was 17964 P1556 which is Charge Pressure Control . I wish I had just left it alone!

 

So either I need to reattach the EGR after cleaning it or look for another problem. I have done the Mr Muscle thing already. I have checked all the hoses

faulty N75?

 

Also check all the vac pipes attached and in good condition, check electrical connections on Maf, MAP & controllers - I had a diesel rover with a serious case of wires too short, ended up replacing half the loom due to wires pulling out of the back of connectors, shorting out etc.

 

Google the fault code suggests the following:

http://wiki.ross-tech.com/wiki/index.php/17964/P1556/005462

Yep got that already. Had to tow a big trailer today from Kent to Holyhead hence my desperate need to resolve. I had enough power to tow all the way to around North Wales and then I definitely went limp. Struggled up hills from then on so not sure that engine status caused this as I had been through all the power ratios and gears without any bother over 250 miles. Maybe that suggests a N75 or electrical fail somewhere in the system. I feel the turbo is happy to work given the option by the ECU.

Have you tried with unplugging MAF to see if it works more consistently? I had same issues when I bought my 2001 was MAF for me.