please help giant flat spot

[jedro750]

HI, I've had my 2.0tdi passsat 2007 for over 3 years, 2 years ago I replaced the engine due to the swirl flaps dissolving into the valves, at the same time replacing the duff turbo with a recon,

After 2 years the vnt vanes clogged up and the exhaust impeller had bits blasted away so I've replaced it with a recon turbo from GAP Turbo's with a 2 year guarantee, the new turbo works fine but there is a flat spot between 1500 rpm and 2400 rpm and then the turbo comes in hard, so I look like a Corsa driver spinning the wheels,

I then replaced the air flow meter which has made it better--but still not right. my friend has the vag /vcds? system which shows no new faults, it says the EGR valve is ok, and the car does'nt go into limp mode.

Say I floor the pedal in 2nd gear and wait for the car to accelerate I can see black smoke out of the exhaust just before the 2400rpm kick in .I've previously replaced the N75 valve, cleaned the egr valve and I.m totally stuck now for new ideas. I look forward to your suggestions, regards Gerry.

[Guest 2]

When was the fuel filter last changed?

[jedro750]

changed last night and every 5,000 miles previously, cheers Gerry.

[martin1810]

HI, I've had my 2.0tdi passsat 2007 for over 3 years, 2 years ago I replaced the engine due to the swirl flaps dissolving into the valves, at the same time replacing the duff turbo with a recon,

After 2 years the vnt vanes clogged up and the exhaust impeller had bits blasted away so I've replaced it with a recon turbo from GAP Turbo's with a 2 year guarantee, the new turbo works fine but there is a flat spot between 1500 rpm and 2400 rpm and then the turbo comes in hard, so I look like a Corsa driver spinning the wheels,


I then replaced the air flow meter which has made it better--but still not right. my friend has the vag /vcds? system which shows no new faults, it says the EGR valve is ok, and the car does'nt go into limp mode.

Say I floor the pedal in 2nd gear and wait for the car to accelerate I can see black smoke out of the exhaust just before the 2400rpm kick in .I've previously replaced the N75 valve, cleaned the egr valve and I.m totally stuck now for new ideas. I look forward to your suggestions, regards Gerry.

use VCDS boost data from 1000 to 4500 rpm through the gears in one straight run and post the results. It's possible the turbo supplier have not set the turbo up properly. You could aslo post MAF results. 2.0 turbo's don't come on song until roughly 2400 rpm so that is fairly normal but not if you can feel an obvious flat spot.

[jedro750]

Martin, thanks for the advice, but due to work and distance problems , it may be a few weeks before i can get back to the vcds, didn't want you to think that I wasn't bothering.
Regards Gerry.

[jcdub]

Martin, thanks for the advice, but due to work and distance problems , it may be a few weeks before i can get back to the vcds, didn't want you to think that I wasn't bothering.
Regards Gerry.

Hi, I'd say it the turbo actuator that's at fault. I had similar in a 08 Octavia rs tdi and the actuator was at fault. Vw and darkside developments do a replacement actuator for them.

[jedro750]

thanks, I'll have a look at it as soon as I get a chance, regards Gerry.

[jcdub]

thanks, I'll have a look at it as soon as I get a chance, regards Gerry.

You can test it by disconnecting the vacuum pipe on the actuator and connecting a rubber pipe to it. Then put the free end in your mouth and suck the air out of the actuator meeting you tongue over hole of the pipe and seeing if the vacuum stays steady or falls away.