seat cupra surging

Could be a dodgy recirc valve leaking, its a common fault on the 1.8T engine, costs 23 quid for a new one, get the one off the 225 bhp TT from VAG carparts

Something wrong with amount of boost being allowed - too much boost, computer detects knock or overboost and backs off...

Get it checked.

Thanks for the reply`s , still under warranty with seat so a trip to the dealer is needed.

Tav

Before we start, you need a boost guage.

It's most likely to be a leak somewhere in the system - but without a guage, you can't see what's going on.

"ron" wrote

Yeah, those plastic Bosch devices can fail from new, accelerate hard on boost and then lift off the gas - a sure sign is a owl-like (or wood pigeon) sound from under the bonnet. You could get a new Bosch one, but as they're quite unreliable, you might like to try an aftermarket one, such as a Forge recirc.

Also, check the vaccuum hose connection to the top of the recirc valve, zip-tie it if it's a little loose, or better, replace it with some brand new stuff, preferably of the silicone variety.

Check all the hoses around the wastegate too for leaks and perishing. Infact you could have a sticking actuator, or the wastegate istelf (though this isn't likely, certainly not on a car less than 5 years old). Come to think of it, make sure the end of the actuator is connected well to the wastegate - the circlip can sometimes break and cause extra friction, before giving way completely and leaving you with no boost at all.

I seem to remember the design was changed a while back - today's Bosch valves no longer have the problem.

They were changed about 3 or 4 years ago. Problem with the Forge part is that it operates too slowly and they need servicing. Bailey is the same. The Bosch part should last 2-3 years at least and does exactly what it's supposed to, works really well. A number of people have removed the Forge/Bailey and gone back to Bosch for better driveability.

"Rushing7" wrote

Ah I wasn't aware of that, thanks for the info.