The mysterious rough running issue

[Guest]

So I have a MK1 VRS estate and am aware that the 1.8T can be a pain if it hasn't been maintained. 

The car was cheap so I expected to have to replace a few things and so far I've done the following:

- cambelt and water pump 

- o ring gasket as I found oil in the spark plugs. Plugs are in good condition and have been cleaned and reinstalled 

- breather pipes cleaned 

- New MAF 

- normal service oil filters etc 

- there are no engine lights on and there are no fault codes present 

 

 

 

I still have an issue with running rough. 

Idle is lumpy and there's vibration (perhaps the vibration is more down to a mounting not so much of an issue to me but thought I'd mention it)

i also have hesitancy between 1-2k rpm. Sometimes it sounds like the turbo is spooling and then just goes off. 

Driving over this rev range is fine and if I put my foot down turbo spools fine and boost is consistent 

 

it just seems to be lumpy lower down which is annoying for around town driving. 

 

Edited 23 May, 2017 by Guest

[kentphil1]

To be certain, you really need to scan the system for any fault codes. You mention that you have no codes, what did you scan the car with?,  also, are you certain that neither the "y" breather pipe or the "s" pipe have no splits in them?. The N75 can give issues, but should throw a code. Coils can also give issues, and there is a Skoda recall on these provided yours are still OEM.

 

At the end of the day, everything I have listed are just educated guesses without scan or measuring block information to work from and be more certain.

 

Hope it helps,

 

Phil.

[Guest]

1 hour ago, kentphil1 said:

To be certain, you really need to scan the system for any fault codes. You mention that you have no codes, what did you scan the car with?,  also, are you certain that neither the "y" breather pipe or the "s" pipe have no splits in them?. The N75 can give issues, but should throw a code. Coils can also give issues, and there is a Skoda recall on these provided yours are still OEM.

 

At the end of the day, everything I have listed are just educated guesses without scan or measuring block information to work from and be more certain.

 

Hope it helps,

 

Phil.

Hi phil thanks for the reply. The garage I usually use said they scanned it but I'll push them on what they mean by that exactly...I sometimes get vague answers from them. 

 

Ive considered taking it to an actual dealer RE: the coils...would the recall still be relevant for a 13 year old car? 

[kentphil1]

The recall is relevant regardless of the age of your car, providing that the coils fitted to your car are vag coils and not aftermarket replacements. Just contact your local agent once your are sure they are originals and get them to swap them over.

 

As regards the scan, you really want some kind of diagnostic software - (VCDS, ODIS, or a quality code reader) that can both read the codes properly and log live data as well. Cheaper code readers tend to use the OBDII protocol, which whilst it is better than nothing, there are areas of the ECU that they just cannot read correctly without issues, hence the better software. There is a members map in the VCDS

section, I see your location is South east, roughly whereabouts are you?, as someone may be able to help out with a scan for you.

 

Hope it helps.

 

 

[Guest]

5 hours ago, kentphil1 said:

The recall is relevant regardless of the age of your car, providing that the coils fitted to your car are vag coils and not aftermarket replacements. Just contact your local agent once your are sure they are originals and get them to swap them over.

 

As regards the scan, you really want some kind of diagnostic software - (VCDS, ODIS, or a quality code reader) that can both read the codes properly and log live data as well. Cheaper code readers tend to use the OBDII protocol, which whilst it is better than nothing, there are areas of the ECU that they just cannot read correctly without issues, hence the better software. There is a members map in the VCDS

section, I see your location is South east, roughly whereabouts are you?, as someone may be able to help out with a scan for you.

 

Hope it helps.

 

 

 

Thays great to know about the recall thank you! 

 

I live in the aldershot area in Hants but am happy to drive a little way out if needs be 

[OctyEstatevRS]

It might also be the Temp Sensor (part number 05991950A), mine has started doing the same in the warm weather.

 

Now its just finding one of the sensor's without paying dealer price.

 

 

[Guest]

52 minutes ago, OctyEstatevRS said:

It might also be the Temp Sensor (part number 05991950A), mine has started doing the same in the warm weather.

 

Now its just finding one of the sensor's without paying dealer price.

 

 

Ah that's interesting...what do you experience is it lumpy idle or all round jerkiness?

[OctyEstatevRS]

Lumpy idle.

 

However, today in the heat all round jerkiness.

 

 

[kentphil1]

Chrisjroe, if your local garage has VCDS or good diagnostic software, you can compare the reading from the gauge side of the sensor with the reading for the ECU side of the sensor. The sensor has 2 outputs, and does not just run the gauge. If you decide to fit a new sensor, take a bit of advice, go dealer only, as this forum is absolutely littered with pattern part premature failures over the years - some do not even see the week out. This is one of those rare times when you buy cheap and buy twice.

 

How was the car during the colder weather earlier in the year?, usually failed coolant sensors run like a bag of s*** in the cold.

 

Your PCV valve could be gummed up also, and as they are under a tenner are worth changing over 100k anyway. A throttle body clean could also be worth doing as the gasket is only a couple of quid.

 

 

[OctyEstatevRS]

On 5/24/2017 at 22:38, kentphil1 said:

Chrisjroe, if your local garage has VCDS or good diagnostic software, you can compare the reading from the gauge side of the sensor with the reading for the ECU side of the sensor. The sensor has 2 outputs, and does not just run the gauge. If you decide to fit a new sensor, take a bit of advice, go dealer only, as this forum is absolutely littered with pattern part premature failures over the years - some do not even see the week out. This is one of those rare times when you buy cheap and buy twice.

 

How was the car during the colder weather earlier in the year?, usually failed coolant sensors run like a bag of s*** in the cold.

 

Your PCV valve could be gummed up also, and as they are under a tenner are worth changing over 100k anyway. A throttle body clean could also be worth doing as the gasket is only a couple of quid.

 

 

Any idea on the PCV part number?

[kentphil1]

Here you go - 035103245A The valve is metal, not plastic.

 

[OctyEstatevRS]

Thanks.

 

Probably try VW first as local Skoda seems to be alot more expensive than anyone else.

 

Will also look at the various hoses too.

 

All seem to be (or at least could be) part of a problem.

 

Together with MAF and TB.

 

 

[kentphil1]

you can clean the MAF by removing the unit from the housing, placing it in a sandwich bag filled about 25% of the bag with Isopropyl Alcohol, then giving it a gentle shake and leaving it to soak for about 5 mins, then remove it from the bag to air dry for 10 mins before refitting to the car.

 

Check your Y breather pipe at the cambox for holes underneath the y as they rot there, also check the s pipe on the inlet manifold for splits as they are weak there too. The dipstick tube can break and allow unmetered air in the system, and the throttle bodies gunk up after a fair mileage.

 

You can remove and clean the throttle body whilst still connected to the loom but unbolted from the manifold if you have a helper hold the throttle wide open while you clean it. If you unplug it, it is a 50/50 shot whether the body will realign or need VCDS to force a reset. Definitely do not force the valve open if it is disconnected, as this is really asking for a new throttle body as the internals scramble themselves.

 

Hope it helps.

 

 

[buddy]

Have you tried all of the vacuum hoses as if one has come off this can cause ruff idling 

[Guest]

28 minutes ago, buddy said:

Have you tried all of the vacuum hoses as if one has come off this can cause ruff idling 

Hey. I've decided to take it to a dealer (probably the first time I've done that in about 5 years with any car) just so they can scan and assess accordingly. It seems to also be influenced by temperature so perhaps the sensor there is buggered 

 

i think you are right about the pipes to although I'm not too competent and wouldn't know a vaccum pipe from a coolant pipe etc 

[Saints92]

I had a rough idle as my Timing Chain Tensioner was starting to fail, replaced that and everything seems fine. Took seven months of it before a fault code finally sprung up pointing towards it (Inlet Camshaft Over Retarded - Intermittent), I'd often hear a slight rattle just after start up.

 

Its a very expensive repair though, so you'd have to be certain its that before doing anything about it, but this is what happened with me.