Jerky when cold or not on boost N75 valve

[jonnyblease]

I bought my cupra a few days ago and i have not had anything turbo before so was not knowing what to expect.

anyway once the car is warmed up at around 90C its fine in the lower revs its a tiny little bit jerky before boost and as it comes onto boost but its hardly noticable at all. As soon as i work my way up to the higher rev range (2.5krevs onwards) it is fine and pulls no issues.

The strange thing is when the engine is cold its like the above but i obviously dont try and hit the higher revs when its cold but its alot more jerky around the lower revs.

What do you reckon this could be? The car has been remapped by star performance and has a green cotton panel filter.

Only other thing i could think of is the airbox has like a hairline fracture in it!

Thanks

 

[jonnyblease]

I have just found out from the previous owner that its because he has changed the N75 valve to a H valve so it generates more boost but it isn't as smooth delivery unless its being fully accelerated.

How does this sound, i have the original valve still. Is it C originally?

Thanks

 

[jonnyblease]

Right im going to clean the MAF out tonight as the car has an aftermarket filter on it which will be more oily i imagine. What can i use to clean it? I was going to use some form of electrical plug/appliance cleaner that will eveaporate going to pick something up from comet tonight. Will that be ok any reccomendations.

Also the airbox has been 'smoothed' out by the previous owner, will this effect anything?

Please somebody help me out