Strange Runnings.....

[Russell Bell]

Hi chaps!

I have an odd one for you. Having spent weeks searching the internet, and spending lots of money, im no closer to solving an issue with my 2014 S3 8v.
Its stage 1 tune, Forge carbon intake, gfbdv+, VW racing turbo elbow.

It developed an engine vibration at idle weeks ago. Thought it was plugs, nope.
Thought hey its coils....nope.
Ran a few tanks of fuel thinking maybe some petrol was contaminated, i cant say either way but my hunch is ...well..nope again.
Some days also, you can feel the power is slightly down. I have checked all hoses for vac and boost. Its strong as an ox with no breaches or cuts/flaws.
Holds brilliant boost but feels slightly lacking. Some days the engine vibration is much more pronounced, some days hardly there at all.
Now i am going out of my mind on this one. NO codes being thrown. Just uses a little more fuel than normal, vibrations and power dipping.
What on earth could this still be??? Im now thinking could this be a leaky injector?
That ties into sporadic changes, engine pulsing, power fluctuations etc.

I dont know, sorry for the ramble. If you have ever suffered from this, please chime in. Ill listen and respond to what ever we come up with

 

[RO65ERS]

Who did the map?...

 

[paradigital]

I had similar on my MK1 Seat Leon Cupra R after running it mapped for a few years. Ended up needing a new dogbone mount.

 

[deanshaw24]

Get it on a dyno

 

[MikeParkin]

Manual or Stronic ?

 

[Russell Bell]

Manual or Stronic ?

s tronic. Had new gearbox oil and haldex service. The box has always run like a dream too

 

[Russell Bell]

I had similar on my MK1 Seat Leon Cupra R after running it mapped for a few years. Ended up needing a new dogbone mount.

i have to be honest, if this is all it is to fix it, id be pretty happy with that. Could just do without any major upsets.

 

[MikeParkin]

Do you have the gearbox mapped?

 

[Russell Bell]

Do you have the gearbox mapped?

no not remapped as of yet, but its something i want to get done.

i had a mini break through yesterday, id had the exhaust flaps switched off via VCDS weeks ago.
Went back and reaactivated them and that judder pulse is much much less present and very hard to feel now, but still there.

i have dropped oem brand new plugs in today. Double checked map sensor, its all clean and seems fine connected or not.
Sat and idled perfectly for a minute or so, then just started to introduce a small vibration pulse.
Its just enough to annoy you and wonder what is wrong.

In theory if their are periods of idling where it can achieve a solid perfect idle, then the pulses are something happening.
I need to get someone to put it on ramps and really inspect every join on the exhaust looking for tiny flaws.
I mean anything, any small hole or less than perfect seal somewhere.

my search and mission continues.......

 

[PanamaS3]

definitely get TCU mapped....and I'd change OEM plugs to a step colder (I have RS7 ones which fixed 99% of my judder on start up)

 

[Russell Bell]

definitely get TCU mapped....and I'd change OEM plugs to a step colder (I have RS7 ones which fixed 99% of my judder on start up)

i most def want the dsg mapped. it would make a huge diff. im booking my tuner guy to run his diagnostics and see if he can spot something obvious.
im convinced its overfuelling as i seem to be killing petrol right now compared to any other time.
lambda at idle reads .993 to 1.0 so its a head scratcher for sure

 

[GW1]

i most def want the dsg mapped. it would make a huge diff. im booking my tuner guy to run his diagnostics and see if he can spot something obvious.
im convinced its overfuelling as i seem to be killing petrol right now compared to any other time.
lambda at idle reads .993 to 1.0 so its a head scratcher for sure

I had a very similar problem some years ago with a Mazda 3mps. The problem was traced to the pre and post exhaust catalytic sensors. One sensor was in conflict with the other, one was saying it need more fuel and one was saying it was over fuelling. My fuel consumption was high and I had appeared to have a judder on idle.

 

[Russell Bell]

ok its all fixed.
Loose fuel cap caused all this trouble. It caused so much imbalance in the fuel/evap system, it caused lots of running issues. It has shown me how extremely sensitive these cars are to any changes in the system like this.
As soon as the cap was dealt with and sealed, car runs smooth, quiet, quicker with no judders and no odd behaviour.
The pressure up front on the PCV valve has now subsided too as a result.

Before hand, the oil cap pressure was way way too strong in the valve cover. Cap sealed = small resistance now in the head as it should be.
Luckily i have sorted all this before that pressure begun to find places to leak and further add more problems.

 

[GW1]

ok its all fixed.
Loose fuel cap caused all this trouble. It caused so much imbalance in the fuel/evap system, it caused lots of running issues. It has shown me how extremely sensitive these cars are to any changes in the system like this.
As soon as the cap was dealt with and sealed, car runs smooth, quiet, quicker with no judders and no odd behaviour.
The pressure up front on the PCV valve has now subsided too as a result.

Before hand, the oil cap pressure was way way too strong in the valve cover. Cap sealed = small resistance now in the head as it should be.
Luckily i have sorted all this before that pressure begun to find places to leak and further add more problems.

Great news glad you have resolved the problem. You are right modern engines have numerous systems in place for emission control and one issue in one part of the system, wham you have a problem.

 

[PanamaS3]

glad you got it fixed!