Hesitation under WOT

[CupraTOC]

I have an issue where under Wot and normally in third gear, the car pulls hard up to around 3.5 to 4k revs and then there will be slight hesitation and the revs will drop around 100 rpm for a split second and then pick up again and the car will pull hard again up to redline. It is not clutch slip because the revs never rise, they drop off.

Cupra MK2
Stage 1 Bluefin
GFB DV+
Turbo Back Milltek with sports cat
Replaced cam follower
Fully serviced inc plugs
Everything else standard.

 

[leontsibob]

Mine does this sometimes, not sure why, mine is a 1.4 tsi, is yours all the time

 

[Dan FR]

Misfire? Changed coilpacks?

Could be a number of things, is it new or did it occur since adding the map for example? Do you have VCDS? If not, find someone who does

 

[Unit9]

Maf
boost leak
coolant temp sensor
lambda,

You need to get it on vcds

 

[CupraTOC]

Maf
boost leak
coolant temp sensor
lambda,

You need to get it on vcds

Had it health scanned and there was just one error that came up which was to do with the interior alarm sensor. No other errors were found.
I have heard of people mostly with the MK1 ko3 turbos, replacing N75 valves with very similar issues to this? Do these cars have one of these?

 

[Dan FR]

Health scanned i.e. fault codes read is often useless on its own. You need live data from VCDS. Data logging to pinpoint the cause is needed.

Never heard of an N75 valve fail on a TFSI - totally different generation of car to the 20VT

 

[CupraTOC]

I won't be able to do that, the chap who worked at our place who had it has now left.

 

[OldManPooley]

Misfire? Changed coilpacks?

Could be a number of things, is it new or did it occur since adding the map for example? Do you have VCDS? If not, find someone who does

May be use full to answer all the above questions when people are trying to help......

 

[CupraTOC]

May be use full to answer all the above questions when people are trying to help......

No misfires, coils not replaced, always been there before remap and VCDS answered above. It seems that without that, all the knowledge on the forum will not help as it could be a multitude of things.

 

[OldManPooley]

Yep, or your just pissing in the wind hoping to get lucky.

Got a Vag specialist near you? Where are you based?

 

[CupraTOC]

West Midlands so got a few around. It isnt too bad at the moment, I don't really fancy throwing money at it unless it gets worse. One thing that could do with replacing is the fuel filter. 62k and don't believe it has been replaced yet.

Do you need to depressurize the fuel system at all before taking out the filter? I have tried searching for a guide but can only find diesel guides.

 

[Dan FR]

I won't be able to do that, the chap who worked at our place who had it has now left.

Plenty of people on here, or on the Facebook Group 'VCDS Users UK' that could help out with VCDS

No misfires, coils not replaced, always been there before remap and VCDS answered above. It seems that without that, all the knowledge on the forum will not help as it could be a multitude of things.

Bit of a silly thing to say really. it's nothing to do with knowledge - virtually everything on these cars is electronically controlled by one of the many ECU/systems on board - so any issue could be caused by one of dozens of sensors measuring a variety of things, or indeed a mechanical issue that is picked up or noticed by one of the many sensors. That's why without data there is not a lot anyone can do to help, except for listing a multitude of parts that it could be, which isn't going to help you unless you want to spend £100's changing them in the hope it will fix it, which you obviously don't want to do as per your below comments in bold...... You can only self diagnose things and avoid taking it to a garage if you have the equipment yourself to do the same thing they would do

West Midlands so got a few around. It isnt too bad at the moment, I don't really fancy throwing money at it unless it gets worse. One thing that could do with replacing is the fuel filter. 62k and don't believe it has been replaced yet.

Do you need to depressurize the fuel system at all before taking out the filter? I have tried searching for a guide but can only find diesel guides.

Just make sure the ignition is off and you do not open the drivers door as both these actions prime the in tank pump. No need to depressurise as its a fairly low pressure system and you'll only lose a small amount of fuel. Job couldn't be any easier really, you don't even need to jack the car up if you're running at standard ride height, although parking on the edge of a kerb will help give you an extra inch or so which will make life easier

 

[CupraTOC]

OK, I will proceed to replace the fuel filter first and may look at coil packs when I service. Thanks for your time folks.

 

[andypower]

If it was coilpack or spark plugs it would throw up a misfire code . When it happens the dash would flash up briefly with the engine light.
Dirty injectors wouldn't throw up one though.

What's the idle like. Lumpy?

 

[CupraTOC]

Idle is good, sits around 800rpm. May add some injector cleaner.

 

[andypower]

You can send them off to get cleaned. I'm driving a megane rs now but it only cost me 60 quid. Really good service.

I'd do that and change the cam follower if you haven't already

 

[CupraTOC]

I changed the cam follower ref the last post in the link. It looked fine but changed it anyway.

http://www.seatcupra.net/forums/showthread.php?t=174856

 

[CupraTOC]

Update...

So I had the underbelly off today to change the oil and filter. I discovered that the boost pipes fitted to intercooler were not fully seated, with the worst of the two being the black one and the red was just slightly out. I had these pipes out last year to change the seals and the horseshoe clips as they were hanging out last year but a lot more than this.
The pipes were not loose and I could not pull them out without removing the clips, they have just dislodged and stayed like it.

Is there any upgrades or tweaking that can be done to stop them coming out, has anyone else had this problem and could this be causing the hesitation if the pipes are moving and leaking boost maybe when the engine rocks on acceleration?

 

[CupraTOC]

Have done 100 miles since refitting pipes and they have moved out again as above. Do I need to change the intercooler or the pipes to stop this happening?

 

[Dan FR]

You'd need to examine both the pipe and itnercooler connection to see which has worn. Perfect excuse to upgrade and do away with those troublesome bayonet fittings