Car losing power mid-high range

[goku4ever]

Hi guys

I've recently purchased a 06 gti dsg. I've recently noticed the car is losing power after 55mph and there's some sort of loud whistle noise.  From standstill the car pulls nicely without the weird whistle type of noise.

The car has been remapped. Looking at the invoices from the previous owner, it has Dv G version,  roughly 2yrs2\8k miles ago. Oh yeah, it has the rtech pcv delete and rear pcv also blanked.

I'm no mechanic but can carry the basic jobs.

Your help and advise is greatly appreciated.

[tyc00n2]

Do you notice that rev's will not want to go beyond about 4k? if so the car would most likely be going into a limp mode. As you pointed out the car has the latest DV and the PCV has been sorted. Taking off the DV is only a 10 minute job so i'd take it off and check the diaphram anyway just to see. Other than that check all your piping to the intercooler and all the hose clamps are tight.

Does the car have an aftermarket intake?

[pudding]

I would be inclined to refitting the OEM PCV system and a GFB DV+, and go from there.   

The turbo should be silent unless it's running an aftermarket intake, is running way more boost pressure than standard, or has a boost leak.

[goku4ever]

Do you notice that rev's will not want to go beyond about 4k? if so the car would most likely be going into a limp mode. As you pointed out the car has the latest DV and the PCV has been sorted. Taking off the DV is only a 10 minute job so i'd take it off and check the diaphram anyway just to see. Other than that check all your piping to the intercooler and all the hose clamps are tight.

Does the car have an aftermarket intake?

Not sure if it revs higher than 4K, will have to check. Having said that, I had a scan and no errors.

The car has standard intake.

Picked up a DV g revised and a cam follower (no record to prove it's been done). Will check DV and if it needs replacing I have one ready.

[Dan_FR]

My Money is on the G being split. Makes a mapped GTI as slow, or slower, than a standard GTI

[AJP]

DV is also the first thing I'd check. If you've got the 'lots of turbo noise but not really going anywhere' symptoms I'd put a tenner on it.

I reckon I was losing about 20bhp at least (according to the arse dyno) on the old rev C. Swapped for a G and it was like a mini remap.

That was a couple of years ago, and it's been running quite a bit of boost since, and it still pulls hard. I might be one of the lucky ones - plenty of people don't get much life out of a rev G, even though they hold boost nicely until they start to fail. I am tempted to put a new G or maybe a DV+ in soon though, just for peace of mind.

[goku4ever]

Removed the DV and it was C revision but no rips on rubber. As I had G revision, went ahead and changed it, but no luck. Loud whistling screeching noise and no power.

What else can it be? No errors on VCDS

[AJP]

Removed the DV and it was C revision but no rips on rubber. As I had G revision, went ahead and changed it, but no luck. Loud whistling screeching noise and no power.

What else can it be? No errors on VCDS

Damn. I lose a hypothetical tenner then. Looks like some further investigation is required...

A screeching noise screams boost leak to me (pardon the pun). The intercooler hose connections are another weak link. Oil around a joint can be indicative of a bad seal.

If you get to the point where you've physically checked everything you can it might help to do some logging with VCDS. This goes further than the usual fault code troubleshooting. Often there's a fault or two that don't actually throw a code - so live data logging can tell you more.

@Pudding & @Dan_FR both know their stuff with logging, and can hopefully tell you the specifics.

NOTE... Can somebody properly tag Kev and Dan for me please, I'm yet to find a way of doing it on Tapatalk. Cheers :)

[MIJ_JAGGER]

[Dan_FR]

Check block 032 for the fuel trims, without a fault code clear as this resets them.

As for logging, have a look here and start with round 1: http://www.goapr.co.uk/support/datalogging.php

[goku4ever]

Don’t know if any of this will help to find the problem;

I’m averaging 14mpg, normal city driving. 70miles from £20 fill. poor??
AC not working ( pressure sensor needs replacing)
Outside temperature sensor the one behind front  bumper grill is missing.

I’ll have to find someone with VCDS for live logging and check block 032

[MIJ_JAGGER]

Don’t know if any of this will help to find the problem;

I’m averaging 14mpg, normal city driving. 70miles from £20 fill. poor??
AC not working ( pressure sensor needs replacing)
Outside temperature sensor the one behind front  bumper grill is missing.

I’ll have to find someone with VCDS for live logging and check block 032

If the ambient sensor is missing then you'll probably have a crazy reading which means the AC compressor won't run.
When my ambient sensor wasn't working I had a reading of -35c, soon as that got fixed the AC was working

[goku4ever]

Don’t know if any of this will help to find the problem;

I’m averaging 14mpg, normal city driving. 70miles from £20 fill. poor??
AC not working ( pressure sensor needs replacing)
Outside temperature sensor the one behind front  bumper grill is missing.

I’ll have to find someone with VCDS for live logging and check block 032

If the ambient sensor is missing then you'll probably have a crazy reading which means the AC compressor won't run.
When my ambient sensor wasn't working I had a reading of -35c, soon as that got fixed the AC was working

For some reason mine changed between between 17-18c. And I don’t even have a sensor, plug is just loose

[pudding]

Loud whistling / screeching when you put your foot down and no power, plus sh*te mpg........hmmmm.   If it were me I would be dropping the downpipe to check for turbo shaft play.   Obviously internet advice is pure speculation without seeing the car, but it sounds to me like the turbo's compressor wheel is rubbing the housing.  It would certainly explain the complete absence of any power.

Take that as worst case but it really needs to get to a workshop for more in-depth analysis.

Lol, love the pudding reference    I am a bit partial to a syrup sponge 

[goku4ever]

Can’t seem to find anything. Go the car booked at http://audivwspecialist.magicallydesigned.com in Harrow.