Hey all,

After cleaning the throttle body and having a rough idle since,(five weeks) took it to the dealers this week and they found that it needed a pre cat lambda sensor. Having done this the rough idle is still there all vacuum hoses intact, still holds a vacuum but code 17705 persists with the rough idle. Been in there since monday and they are now waiting for Skoda UK tech to get back to them. They have checked all the usual suspects.

Anyone any other ideas?

MTIA

You say usual suspects.... Such as:

• All boost and ancillary hoses
  
• Leaking on the: Down-pipe, exhaust manifold gasket/flexi hose.
  
• Cracked exhaust manifold - this is more common than you might think!!!
  
• Crankshaft sensor
  
• Coil packs/plugs
  
• Coil pack wiring harness
  

All of the above can cause what looks like an o2 sensor faliure.....

Steve

if you needs coil packs mate, I have some spare - pm me if interested

With rough idle if cleaning the throttle body doesn't solve it, I would replace the coolant temp sensor next as the original black CTS is notorious for failing, & causes incorrect fueling which then manifests itself as rough idle. CTS failure rarely throws a code so main dealer fitters usually don't spot it's faulty. No code & they're lost!! Personally I wouldn't expect Skoda to solve either of your problems, a good independent VAG specialist is far more likely to solve issues such as you're experiencing.

As for 17705 code that can be a nightmare to pin down. A smoke test should reveal any boost & vacuum leaks. OEM DV is prone to failing & diagnostics usually advise check DV for 17705 (pressure drop between throttle & turbo)code. Also if your car is remapped beware as there are a lot of generic maps floating around that have an incorrect value in the software that throws 17705 on cold start up.

With rough idle if cleaning the throttle body doesn't solve it, I would replace the coolant temp sensor next as the original black CTS is notorious for failing, & causes incorrect fueling which then manifests itself as rough idle. CTS failure rarely throws a code so main dealer fitters usually don't spot it's faulty. No code & they're lost!! Personally I wouldn't expect Skoda to solve either of your problems, a good independent VAG specialist is far more likely to solve issues such as you're experiencing.

As for 17705 code that can be a nightmare to pin down. A smoke test should reveal any boost & vacuum leaks. OEM DV is prone to failing & diagnostics usually advise check DV for 17705 (pressure drop between throttle & turbo)code. Also if your car is remapped beware as there are a lot of generic maps floating around that have an incorrect value in the software that throws 17705 on cold start up.

Cheers for that.

They are still no nearer to sorting it.

had CTS replaced earlier this year.

When you say OEM DV are you referring to the recirculation valve thing?

Ta

Cheers for that.

They are still no nearer to sorting it.

had CTS replaced earlier this year.

When you say OEM DV are you referring to the recirculation valve thing?

Ta

That comes as no surprise.

As long as the replacement CTS was a genuine VAG part I doubt that has failed. If it was aftermarket that's a different story entirely. There are many tales of failed aftermarket CTS's.

Yes OEM DV is the recirculation valve.

If the CTS is ok I would strongly suspect that you have a split boost or vacuum pipe somewhere.

As I said earlier you really need to find a good independent VAG specialist. Awesome GTI, Shark Performance etc.

Have you changed the spark plugs?

All been changed, all hoses and pipes been pressure tested and vacuum holds well.

Im thinking I need to try and swap throttle body and DV to see if thats the problem. Does anyone know a way to test the DV?

Many Thanks.

Chris

Remove the DV push the piston up then put your finger over the small pipe on the top, release the piston & it should stay up until you remove your finger off the top. If it drops while your finger is on the top pipe the seal has gone.

Thank you. Ill give that a go tomoz.

Cheers Chris