2007 FR 170[PD] down at 130 on RR (logs and dyno graphs included)

[dreamonn]

Took my 2007 FR TDi for a remap today & got a bit of a shock... The first run on the rolling road showed peak power down at ~130BHP & an odd looking torque curve

A scan showed no fault codes, so some data was logged & the only thing that caught the mechanic's eye was the boost taking longer than expected to reach maximum. Full boost was requested ~2000rpm, but wasn't achieved until 3300rpm. Is there a way to attach logs or include them in a post?

He suggested that it may be due to a faulty N75 valve or possibly the turbo - has anyone seen a similar problem or know what the problem could be?

The car is my daily drive & certainly doesn't feel down on power so I'm guessing it has been like this since I bought it 2 years ago. It hasn't missed a beat & regularly achieves 40-45mpg on my daily commute.

 

[GrahamFR]

if its been like this for 2 years i wouldnt think it was your turbo, it wouldve been fine and then crap, you might wanna get it to a different RR or check out this N75 valve, but if you are 130 i feel for you mate, but think how well it will be well you fix it and get it to 70bhp more than before lol

 

[dreamonn]

Cheers mate

I'm hoping someone will recognize the symptoms & confirm what the problem is.

I've asked Dave @Sere for a price for a N75 valve.

130BHP includes the Milltek that was put on last weekend - wonder what is was with the standard system?

 

[GrahamFR]

lol well i dont no if anyone on here will have not noticed running 40bhp less for 2 years but hopefully someone might be able to help you. have you asked a vag specialist?

 

[dreamonn]

Not yet, spent this afternoon sulking

It's booked in for a service on Saturday so I'm gonna speak to my mechanic tomorrow & see what he thinks

 

[champo]

Hi,

i think id look at the requested boost and actual boost figures on the car using vag com. perhaps replace the n75 to see if this makes any difference.

then it could be worth looking at the turbo

Ive seen this on a mk4 golf with a replacement turbo.

im just guessing that this turbo could be the same type of variable vane turbo.

what was happening on the golf was the vanes were pitching too much on the turbo, so the airflow was going just past the point of the best pickup and becoming less efficient at the point that the most efficency was required.

its quiet hard to explain, but if you read up on or know how the variable vane turbos work hopefully you will see what i mean.

theres a simple way to fix this. there is a stop screw that limits the maximum movement of the vanes on the turbo housing. to adjust this just undo the locking nut and wind in the stop screw half a turn at a time until the turbo feels to spool up quicker.

hopefully this will help give you more ideas of what could be wrong after ruling out boost leaks and other things.