car not running correctly

[SuperVillan]

Hi guys hoping you can help here as this is driving me mad, i got a vw golf gti mk5 fsi 3 months ago car seemed fine when i picked it up but after having it for a few months problems have started to roll out, i have dealt with all of these except for my current issue which is, when the car is first started for the first 2 minutes it feels like the power wants to come but is being held back by something almost like somebody has stuck a potato in my tailpipe. it makes all the noises but is not moving like it should give it the two minutes if that then its fine pulling through all the gears like it should. any clues ? nothing is showing up on the vag no error codes it really wired

List of all the things i have replaced with new VW parts from the stealer

Coolant temp sensor
DV valve
Cam Follower - no issue with this had the part so change anyways
PCV checked no issues
no pressure leaks

[GrayMK5GTI]

Blocked cat maybe?

[AJP]

The first thing that came to mind was lambda sensor.

[schmidt_vr6]

Have you had it on Vagcom?

But by the sounds of the symptoms. I'd suggest the MAF Sensor.

[SuperVillan]

nothing coming up on Vag at all bit of extra information car did seem to be over fueling by the looks of the spark Plugs but this could have been down to coolant temps sensor, anyhow the cat has been checked and seems fine no rattles and as i said its only for the first 1 / 2 minutes after which the car runs normal without any power drops or issues, maf sensor would cause again a continuous issue not short term issues. but thanks again guys anbody else ?

[andy7ven]

I've got an intermittent fault at the moment too. No warning lights or anything but occasionally car won't accelerate above 2500 rpm/40 mph. I push the accelerator pedal to the floor all I get is a loud hissing sound - turbo is working but no power!  If I ease off then accelerate it's back to normal!

Divertor valve was changed about 2-3 years back, PCV never changed...

Any ideas, car's booked in for next week but as I say it's intermittent and I know they're going to say nothing wrong £100 diagnosis charge please!!! 

[SuperVillan]

PCV valve is easy to check start car pull the pipe off,  you should see the engine drop and start to run like sht, dont leave off for too long 10/30secs max, yours does sound like a sticky DV valve but it all comes down to one simple thing, are you able to investigate the fault do you have tools jack stands ramps and jack if not this is a pointless effort 

[andy7ven]

No tools and a sloping drive! Thanks for your help and suggestions though :)

I was thinking DV Valve again as when the car is running ok you can hear the same sort of whistle/hiss noise as when I had the original DV with the torn diaphram and it doesn't pull as good as when it was changed...

[W6llace]

Hi, I read somewhere on here that in cold weather the ecu doesn't allow full boost until you get to a certain temperature?

[SuperVillan]

ok i live in England people not the sun, not a lot is going to have changed in respect to engine temps in 2.00 mins worth of driving