Well after about 2300 miles without a FC being recorded, I drove 4 miles rather spirited earlier and soon afterwards hear the Dump valve fluttering rather than fairly quiet shssss sound. I mentioned to my daughter that was in the car at the time that its sounding a lot different and she agreed. When we got home i lifted off the engine cover and took a look at the Forge 007P as when i got it the larger nut wasn't as tight as i would have preferred so just checked to make sure it hadn't worked loose. upon inspection i found nothing untoward and put the cover back in place. Tonight i had to do a 50 mile round trip but no sooner had i got about 5 miles up the road the EML was on with no difference to running or performance.

I turned off and plug in the FCR and got the following codes:

17608 (Fault with DV or Diverter valve)

16795 (secondary Air Control fault)

At least it wasn't the 17705 fault again, Mine was a dirty throttle body (last thing for me to check).

I still have the original Dump valve that I had replaced during bouts of 17705 FC's which i can pop back on tomorrow but wonder if its more likely to be the diverter valve? I have a couple of spares if that's the part that has the 3 pipes coming out of it and sits next to the Dump Valve.

I've had the dump valve piping pop off numerous times and its never gave a fault code.

Any advice on this one? shall i try replacing the Forge Dump valve? or just head straight for the replacement of the valve under the dipstick tube?

Swap dump valves, only a 2 minute job worth seeing if it is the problem, that's the only thing you messed about with before your problems started

Right, done some more on this this evening, removed the n249 valve and tested it. All appears to be working 100%. Removed the n112 valve and during testing found it to be leaking air from the blanking cap, fitted some tape over the tube and pressed the cap back on. And confirmed both valves were 100%. Took the car for test drive after erasing codes and now left with the 17608, then replaced the n75 valve and performance is back but its pulled the code up again. Have fitted standard recirc dump valve back on too.

Help?

Is the vacuum feed pipe to the top of the DV ok? I.e. not blocked or not crushed by anything?

The dump valve top pipe seems ok. I refitted the forge dump valve 20mins ago and just starting and revving then checking for fault code its back straight away.

Are there individual fuses associated with these valves?

There's a multiplug to the N249 but no electrical connections to the DV. Might be worth checking the multiplug and wiring isn't broken. The N249 might be mechanically sound but if the wiring is dodgy then it could be shut when it's not supposed to and not letting vacuum through for the DV to open.

You could try running without an N249 i.e. use a vac feed straight from the manifold to open the DV.

From the fluttering noise you described it sounds like the DV isn't being opened properly when it should be so there's definately something not right in the pipework in orange in Rob's diagram here:

http://www.pimpmyskoda.co.uk/V2Images/ModsEngine/N249Removal.htm

I've ordered some vacuume hose and intend to replace the hose to and from the dump valve, resoivoir etc. Something is making me think the power isn't getting to the valves though. Where is the multi connector?

That image will help though thankyou.

Also discovered that both rad fans are on all the time too. Even with the climatronic off.

Starting to get quite disheartened by the car now. :(

If you take the plate off from in front of the manifold that the N249 and the vac-pipes are all mounted on you should be able to find the multiplug going into the N249.

Under normal operation the N249 just stays open so the vacuum from the inlet manifold directly opens the DV when the throttle is closed. When there is an issue with the turbo overspeeding though the ECU can send a signal to the N249 and it is able to switch and route vacuum from the vac reservoir to open the DV instead and vent the boost at part throttle as a safety measure.

I'm guessing the N249 is maybe stuck in that "switched" position due to an electrical fault since you've checked it and mechanically it appears to be working ok.

No idea re. the cooling fans - possibly the fan switch needs replacing. There have been a couple of people on here with the same problem recently.

If the coolant temp sensor is goosed the ECU could be putting the fans on.

Morning ladies and gents, after going over things as best as I could in the rain last night I'm still no forwarder with this. Tracking wires isn't that easy in a cramped engine bay in the dark. On way to work this morning eml was off till I stopped at level crossing breifly heard a fan start up then eml came on. Now have the 16795 back, had thought cause of that was blanking plug on n112 valve leaking (which I cured).

Has anyone got a full schematic of the engine management system so I can go down to component wire checking? Pretty please!

Paul.

I wonder if the fan you heard starting up was the secondary air pump rather than one of the cooling fans? That would explain the code.

You might have to buy the workshop manual off of ebay to get a comprehensive wiring diagram. There are very simple diagrams in the back of the Haynes manual but they don't go into any detail on the engine loom :(

I've got the haynes manual but as you said engine wiring isnt covered. The cooling fan issue is resolved now. That was corrosion on the conector.

for anyone interested, I have now replaced the Fuel pump relay, got myself Android Torque and dongle. replaced the braided vacuum hose and went for a drive. maximum Psi of boost i got was about 6psi, however after returning home i went out again and had a brain fart! turned off the traction control, as from my understanding that's one contributing factor for the limp home mode, and hey presto had about 20psi of boost. The road wasn't wet so why would the ESP or whatever its called being cutting boost pressure so severely. Does ESP being switched off overide limp mode or is limp mode actually ESP?

Confused! is anyone around worthing, west sussex so we can have a chat?

Edited 20 April, 201214 yr by skudman