Hi guys,

Got a problem with my 2006 TFSI vRS. Brought the car from an independant garage and after a week of so noticed a knocking noise from the engine on tickover, but only once warmed up. The supplying dealer couldn't work out what was wrong and authorised me to go to my local Skoda main dealer - Farmers in Leicester. Must say they've really tried to be helpful.

They thought the noise was a fault with the fuel pump and I secretly dreaded that the plunger on the pump had worn through the follower and damaged the cam lobes. However no such problem and they fitted a new fuel pump at the expense of the independant dealer.

Fuel pump was fitted yesterday and I should have picked the car up last night, but the service guy still isn't happy with this and asked if he could have another look today.

Picked the car up after work and he tells me that although the pump is quieter there's still a noise once the car has warmed up. The supplying independant garage had asked him to add an oil additive to free up any sticking hydraulic tappets and for me to run the car for a couple of weeks to see if this helps.

I'm not convinced, as in my experience sticking hydraulic tappets usually show themselves up when starting from cold and then settle down after a short while.

Anyway took the car and it started up lovely and quiet - could tell the difference the fuel pump had made, as the old one had a slight clicking noise. However within a couple of minutes as the car warmed up, as soon as I came to a standstill I could hear the knocking noise.

When I pulled up at home I opened the bonnet and had yet another look round. Difficult to tell where the noise was coming from, so to see if it was from the camshaft area I took off the oil filler cap to see if I could here anything from in here while the engine was running.

I got a bit of a shock - as I took of the oil filler cap I could feel it there was a vacuum under it. As I lifted it off, the engine started to judder and surge. Put the cap back on and normal (but noisy) tickover resumed. I repeated this again with the same results.

There's a fair amount of vacuum here, far more than I've ever experienced on any other car I've had.

Is this normal ?

If not what could be the problem ?

Is this related to the knocking noise ?

Really hope someone has some ideas - as it seems to have stumped the Skoda dealers so far.

Have you had the car scanned for faut codes? Could be the PCV failed and needs replacing? The usual fault code for this is P0299. Might be worth mentioning it to the mechanic and see if he has checked it?

Yes - I've got a genuine version of VagCom and the hex cable.

Had the car a couple of months and have ran the diagnostics a few times with no engine faults.

However, I ran these again today when I got home and got the following code (copied the text from the RossTech wiki) :-

17501/P1093/004243 - Bank 1; Fuel Measuring System 2: Malfunction

Possible Symptoms

• Power Loss
• Misfire(s)
• Stalling

Possible Causes

• Fuel Pressure insufficient/exceed/fluctuating
• Fuel Pump (High Pressure System) faulty
• Fuel Pressure Regulator Valve (N276) faulty

Possible Solutions

• Check Fuel Pressure (on FSI engines High and Low Fuel Pressure System)
• Check Fuel Pump (High Pressure System)
• Check Fuel Pressure Regulator Valve (N276)
• Check Fuel Filter and Filter in Fuel Pump Casing

Special Notes

• When found in 2.0l TFSI:
  • Check Fuel Pressure
  • Check TSB/TPL 2008753, incompatibility between Fuel Pressure Regulator Valve (N276) and ECU software.

Ran the adaptation routine as described in the notes, but still no difference.

Wondered if pulling of the oil filler cap whilst the engine was running might have caused this ?

Bit of a mystery eh !

Edited 27 May, 201016 yr by VAG-Phil

When they fitted the new fuel pump. Did they fit a new thrust pressure sensor in the pump? I fitted one recently as I snapped the plug cover when taking my BSH revamp off for a clean. They cost about £42 for the new revision part. Id clear the fault code and run it a few days to see if it comes back?

But I would get check the PCV checked as a matter of course. I took mine off and fitted the BSH revamp kit. Never looked back since:)

Thanks for the response.

Not sure if they fitted a new thrust pressure sensor (doubt it), but I ran the suggested measuring block below an all looked ok :-

Checking Fuel Pressure

Prerequisites:

• Ignition ON
• Engine ON (Idle)
• System voltage at least 11.0 V.
• Coolant Temperature at least 80 °C

[select]

[01 - Engine]

[Meas. Blocks - 08]

Group 103

[Go!]

Field 1: Fuel Pressure (Low), Specification: 2800...7200 mbar

Field 2: Fuel Pump Adaptation, Specification: -1000...+1000 %

Group 140

[Go!]

Field 3: Fuel Rail Pressure (High), Specification: 25.0...110.0 bar

Increase the Engine Speed while checking this value, the Pressure has to rise with the Engine Speed.

Group 230

[Go!]

Field 1: Specified Fuel Rail Pressure (High)

Field 2: Actual Fuel Rail Pressure (High), Specification: 25.0...110.0 bar

Field 3: Deviation between specified and actual fuel pressure, Specification: max. 5.0 bar

[Done, Go Back]

[Close Controller, Go Back - 06]

I'll take your advice and clear the error code and check again in a few days.

As for the PCV - if the unit was defective, wouldn't I get an error code for this ?

Really looking for your help with this mystery guys - any ideas ?

Vacum when oil filler cap is open is normal on these engines and yes engines starts to judder. Tickover sound might be a gearbox dual-mass flywheel noise.

Edvard,

Thanks for the reply.

Is there any difinitive way of teling if this is the cause ?

Car has done 42k miles, but I haven't noticed any other problems with the clutch/flywheel.

All help apprciated !

I personally would want a dealer to confirm this.

Surely a crankcase at negative pressure is something just a touch odd.

Bump :-

Any other ideas guys ?

Now the fuel pump has been replaced, the slight ticking noise this was making has gone, but this only makes the knocking noise more noticable and distinct.

Sounds like a diesel ticking over at about half speed.

Don't think the oil additive has made any difference whatsoever.

Thanks to anyone who can help.

Vacum when oil filler cap is open is normal on these engines and yes engines starts to judder.

I can vouch for this. Dutifully topped up the oil on mine the day I got it, forgot to put the oil cap back on. 5 mins down the road, thought I'd been sold a lemon due to the juddering

Took around 6 seconds of in-car thought to diagnose the problem. Muppet.