A4 B7 2.0tdi 170 on off power

Sp3no82

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I am noticing more and more that sometimes it feels like the car is holding back, I apply the accelerator and nothing then suddenly all the power comes at once and it goes off like a rocket. It's not turbo lag as it's holding back around 2200rpm and it does not do it all the time it's a bit sporadic. The cars remapped, has a fairly new DPF a new Turbo with only 3000miles on new fuel filter air filter oil change etc. I give it a good thrashing so happy there is no soot build up. Could it be EGR related?
 
No expert but id be getting some logging done first, you say your mapped and with a new turbo?

Id be logging boost requested vs actual and Maf values first and check they seem correct
 
Mine does that also, more so when cold. Was never as bad when I first got the car and I have replaced the EGR after the old one failed, so it's not that. In all honestly I am putting money on carbon build up on the intake manifold & back of the valves and / or (more likely) sticking vanes on the turbo, as they are meant move as boost builds so it gives a constant surge of power. However if they are stuck in a position that is used for more torque further up the revs then the car will (and does it seems) feel gutless lower down.

Apparently you can clean the vanes with Mr Muscle oven cleaner in situ and free them up or a better way (but much more time consuming) would be to remove the turbo and clean off the car.
 
Ive Mr muscled the turbo on my mk3 mondeo and b5 passat it worked great and confirmed the diagnosis without having to remove the turbo. It did always appear to be a temporary fix and ideally as mentioned above it would need removing. You can confirm the diagnosis with you reqd vs actual boost