(Possibly FIXED!) I'm running out of ideas now (1.9 CDTI 150 low power until 2000rpm)

[John LE]

Ever since I bought my car i've been disappointed with how dead the car is below 2000rpm.

As soon as the car hits 2k it's off like a shot and with a cloud of black smoke.

Since I bought it, it's had

A new inlet manifold
New Vac pipes
The throttle body has been cleaned, cleaned again and i've even driven the car with the throttle body disconnected.
The egr at first was cleaned, then unplugged, then software deleted and then blanked and it's made no difference.
All of the boost pipes covered in fairy liquid but there are no leaks - anywhere.
Umpteen fuel cleaners
New air filter
The bcs stripped and cleaned
Another bcs tried
The maf stripped and cleaned
A known working maf tried

But still the problem persists. I am now onto the theory that the VNT actuator may be sticking (read alot about this on various VAG forums) and i'm led to believe that the vec shares it's turbo with one or two of the VAG diesels.

Anyone come across this fault? If it is the actuator then I think it's time to change the whole turbo and actuator to cure the fault.

It's really depressing me now as the car just feels amazing when the boost eventually comes on

[dh.dti]

I note you have replaced the vac pipes, have you tested the vac solenoids to check they're working as they should

[geordieric]

Clean/remover the turbo control sensor. Sorted my problem at 1-2000 rev.

Its the grey/white sensor on slam panel. Filter is under the black hat. Un-click it first b4 removing filter as its permanently fixed.

Theres a thread on it few days ago.

[hothatch]

Boost sensor could do with cleaning as geordieric states. I notice is missing from your list. lol. Actually ignore what i just said, you got it under bcs lol.

[geordieric]

There's 2 sensors. One which I mentioned which restricted my lower rev range only it seems. The one on back of engine block hampers the whole rev range(I clean that one once a month or whenever I'm playing. Vectras are so much fun

[Rebellion]

But still the problem persists. I am now onto the theory that the VNT actuator may be sticking (read alot about this on various VAG forums) and i'm led to believe that the vec shares it's turbo with one or two of the VAG diesels.

VNT means variable geometry turbo (or variable nozzle turbo to stay true to the acronym). Are you certain the Z19DTH turbo even has variable geometry?

[McLovinH]

I'm watching this thread with interest. You've got the same problem as me an I've tried most of what you have, apart from cleaning that sensor on the slam panel up, only removed the mesh filter off it!

[GazVXLINE170]

Are you sure the Vacuum pump isn't to blame?

[Rebellion]

It looks like you do indeed have a VNT:

http://garrettbyhoneywell.com/produc...w.php?id=75228

[DieselWig]

As GazCDTI150 says, is your vacuum pump working correctly? This pump is responsible for producing the vacuum that pulls the turbo wastegate actuator. So, even if your vacuum pipes are ok and the boost control solenoid is ok, if insufficient negative pressure is being produced by the pump the actuator may not function as it should.

However, firstly I would jack up the car, remove the turbo actuator hose and get some clean hose (4mm ID) and suck on it. You should be able to see the actuator rod pull in against its spring (with a torch probably) with little sucking effort. This could at least show you that the actuator is moving freely enough to be pulled in. If this moves freely, then maybe your vacuum pump is struggling or you have a leak/BCS problem you have yet to find. If not, maybe the actuator rod is stuck.