PD170 - Lack of power under 2.5k RPM

[Cyrix]

Wondering if anyone can help with this.

My car started doing this today, feels like nothing is happening until 2,500 RPM then the turbo kicks in and the car accelerates off.

There is a bit of black smoke, idle is a little rougher, no fault codes or warnings showing though.

With the MAF sensor unplugged the car pulls as it should, though I'm wondering if the fault is actually the EGR valve rather than and issue with the MAF.

I'm sure someone will have had the same issue, it is a VAG TDI engine after all

 

[quattrodave]

Sound like the fault I had.
Check your inlet manifold vac unit, it controls flaps in the inlet manifold and sometimes the diaphragm tears which causes it not to operate. This also reduces the vacuum to the tubo wastegate actuator.
It's easy to test, the unit sits at the very front end of the inlet manifold and is a black plastic unit angled downwards with a right angled black pipe coming off, it also has a black platic arm heading down the side of the manifold.
Pull the angled pipe off and attach a temporary hose onto the unit, try sucking the pipe and if there's no resistance the unit needs replacing. The manifold and egr need removing to change it though but that only take about 45 mins, the hardest bit is cleaning everything out, that took 1.5 hrs.
Big difference when it's done though, idle is smoother and power delivery a lot more linear without the big turbo spike at 2000-2500 revs. It's a 'must do' on any 170 tdi to be honest.
I've got a list of all the gaskets somewhere if you need it, I'll post it later on if you like

 

[Cyrix]

I actually changed the vacuum actuator on the inlet last week, all working (tested with a vacuum pump) the original had a slight split in the diaphragm as suggested. However the car still drove reasonably well before this, mainly as I had just plugged the vacuum line as a temporary fix when I realised this was the problem.

One thing i did notice was there was a slight metallic rattle from the EGR valve when it was off the car, wasn't sure if this was normal or not, the other EGR valves I have played with have been the vacuum operated type rather than electronic like the PD170.

I did clean everything up when it was off the car but to be honest there was only a slight film inside the inlet etc, I do drive the car quite hard though so am not particularly surprised.

 

[Raymond999]

I am having the same problem with mine 170, she had no fault codes but after been in my local specialists for two days this week they found the egr valve was about to give up ghost, which was making tick over lumpy when cold and a intermittent lack of power.
All in all it cost 400 to sort out.