MK5 Golf GTI

Hi all,

First post and hopefully your brains can help me because mine is very confused!  

A week or so ago, whilst on the country lanes at 50mph in 5th, i put my foot down and the car felt like it was stuttering or losing boost. First of all i thought i must have imagined it, however it continued doing it for the rest of the journey, and not just in 5th, it happened at low-mid revs in 3rd and 4th too, but mainly 4th and 5th.

A little hard to explain but it felt like someone pushing you in the back whilst running - or something slipping and then moving again. A light juddering you could say.

Anyway, after some research i thought it could be the DV so bought the new D Pistion type version and fitted that, and for a day it felt a bit better. Then nope it started again. It normally happens under hard acceleration and most noticable in 3rd through 5th. If i properly stick my foot down it really feels juddery in power, but still seems to pull well. It happens to a less extent under normal acceleration.

The car had a major service in May  at the local VW dealer and they completed the 28F5 coil pack recall change then too, so i would think the coil packs are ok.

No codes or faults come up when plugged into vcds, although it is not a proper Vagcom, and no lights on the dash.


I'm really struggling to work out what the problem is - but will not be ripped off by the £90 an hour diagnostics charge the local VW dealer wants.

Car is a 55 plate (nov reg but i think pre the change as has the older style of wiper blade connectors)



Help!!!!! Any thoughts? could it be the PCV?

have the spark plugs been replaced? Could possibly be a fuel pressure related fault, high or low side, might be worth poping your oil cap off and giving it a sniff, make sure it doesnt smell of fuel indicating possible fuel pump cam follower wear.

i believe so yes, replacing the plugs was part of the major service. Had the oil cap off, and seems to smell ok, but had a little tinge to it - couldnt say if it was different than should be. Would it have a heavy fuel smell?

I did wonder if it was something to do with the air/fuel mixture?

thanks for the quick reply btw

ye it would stink in the cam cover if the follower was worn enough to cause a fuel pressure drop. i think it needs to go on proper scanner, have a look round at garages, really you shouldnt be charged full diag if they cant tell you what the fault is, also if it is an involved fault and they carry out the work for you, if its not fixed then you dont pay. Does the fault occur all the time? Is the car remapped?

my money is on coil pack

Car is completely standard, and agree looking like need to do a proper scan, may have to have a word with my local independent place.

Fault didnt occur today (did yesterday) but then it only went 5 miles to the station and back. Idle settles find and not rough either, in case that came up.

Had the engine cover off to look at the coil packs, and couldnt see any part numbers on them to check if they are new versions - but nothing on view - are the part numbers underneath/on the tube part of the pack?

My money is on the N75 wastegate boost solenoid... something my cars in the garage today being fixed... sounds very similar symtoms as to what i had...

Log(or get someone to log) the N75 duty cycle... mine was proper erratic coming on, then suddenly shutting down, coming on higher values to compensate then shutting off... givin gthe stuttering effect i could feel through the pull of the car...

Quote from: E30Dom on September 29, 2011, 12:19:46 PM
My money is on the N75 wastegate boost solenoid... something my cars in the garage today being fixed... sounds very similar symtoms as to what i had...

Log(or get someone to log) the N75 duty cycle... mine was proper erratic coming on, then suddenly shutting down, coming on higher values to compensate then shutting off... givin gthe stuttering effect i could feel through the pull of the car...

Thanks E30DOM will have a look at that for definite. Is it an expensive fix, and where about's is the solenoid -near the N249 DV valve?

It piggy backs the turbo I believe... Will confirm if/when it fixes my problem... Part is £25 but i't fitting thats a pain especially the clips... Hour tops at a decent garage...

Quote from: E30Dom on September 29, 2011, 05:17:19 PM
Well mines all sorted... Thanks APD! 

Is the n75 common as plugs, coilpacks and fuel filter havent fixed mine :( doing revised Pcv later this week.

I had the coilpacks changed on mine under the recall recently and compared to the old packs it is noticably juddery in low revs especially when cold. It seems OK above 2500 rpm though. It was something I noticed straight away and thought maybe it would settle after a couple of days but it's still there. It's worse when cold and only slightly noticable when warmed up.

I take that back... Not convinced it's sorted... Back to drawing board... Do you get a fluttery boost sound also?

Compression Test?? 

http://www.mk5golfgti.co.uk/forum/index.php/topic,35546.0.html

Had a compression test but as PDT Dave said it needs to be more in depth testing to really make issues apparent 

Do get a fluttery boost sound.  Am replacing the n75 valve as matter of course, when I take dipstick out the engine doesnt run like sh*t as expected, in fact there is no change in engine note or hunting.... 

no real fluttery boost sound on mine, more of a 'skip' motion when accelerating, did it on the way home today and definitely worst when in 4th or 5th gear, but flutter/judder/skip would sum it up