Hi guys. 

 

First time poster, and of course it's a problem. i hope to be back with happier chat once sorted

 

Anyway, my petrol VRS recently became slightly reluctant to start - would take two attempts from cold. But was running fine otherwise. Then however it started stuttering/spitting on full throttle over 2.5k and all the way up the revs. Now (a couple of days later) it's running more roughly and not revving nicely at all.

 

The funny thing, (to me) is that it's only in-gear. When the car is idling or revved in neutral it's revs as cleanly as it ever did. No hesitancy or spluttering or anything. 

 

My mechanic identified a fault code as being the intake manifold, but that fault code has been there since I bought the car without affecting the running of the car at all. 

 

I suppose my question is, can I be sure that a new intake manifold will fix the issue? It's quite an expensive job, I've been quoted nearly 800 quid.

 

If you guys don't mind, please don't start telling me I can fix it myself. I'd like to keep the discussion to the actual diagnosis. Does what I've described sound like the diagnosis is accurate?

 

If you've read this far, thank you and if you've any advice for me, thanks even more

 

If it's relevant, the car got a basic remap a year and a half ago with no issues, it's well serviced, in good order, plugs and oil done recently, coil packs replaced under the recall scheme. 

Just because you have replaced the coils and plugs does not make them infallible, have you break down cover, sometimes a cheaper way of getting it diagnosed? to me because it revs not under load, suggests more of a coil pack/ spark plug issue rather than air, in the days of points a car would pink,( pre ignition under load if say spark plug gap wasn't right or not high enough octane fuel used , when we had star rated fuel,Under this system 1 star was the lowest grade (not used for road vehicles), 2 star was 92 octane, 3 star 95 octane, 4 star 98 octane and 5 star 101 octane. The lower end was for the low tuned / low compression older design of engine (and skinflints...) the middle range for more modern (this was the 1960's don't forget) higher compression engines and the skinflints who got sick of that awful pinking noise, and five star was for big, fast, powerful engines. 

Assuming air filter, coil packs, leads and plugs are ok (?), it could just need a good decoke. Most of us with petrol vRSs never use supermarket petrol as it doesn't have the detergents that BP and Shell put in.  They also run better on 98 or 99 RON.  Worth a tank of Shell V Power if you haven't already tried it.

 

If its more serious than that, it all depends what the fault code actually is. If you can't get the code from the mechanic, buy a cheap fault code reader from ebay or ask a Briskodian with VCDS to check the code.

 

A common fault code on the chain-driven Tsi engine (2009 onwards) is P2015 - intake manifold runner position sensor/switch. This is normally when the inlet manifold flaps stick due to oily carbon deposits - it's a fault common to many Tsi VAG engines. but not an issue with the previous belt-driven Tfsi engines.  These videos explain the manifold issues:

 

 

 

Mine occasionally flags this up but so far it hasn't affected performance or economy.  I just reset the code/light and exercise the flap actuator arm by hand with the car turned off.  Eventually I may need to renew the inlet manifold itself though.  There are DIY videos on Youtube but you'd still need to buy a new manifold.  A VAG independent would be cheaper.