2008 Skoda Octavia octavia fuel injection problem

Has the egr valve been checked out?

With the Dealer and Skoda UK not been able to fix it , hard to suggest an answer as they should have covered more or less everything .

SOUND LIKE ACCELERATOR SENSOR OR INJECTOR PUMP?

If your flywheel has deteriorated to such a level that it,s knocking this can cause rough idle as that knock is picked up by the knock sensors located on the engine block which causes the e.c.m. To retard the timing therefore the engine rough effect.compression test would be a first basic check also,turbo issue can cause a total shut down of injectors if the turbo is in a over boost state I.e. the car goes really well then it,s like some ones stamped on the brakes .The best way to prove any of these theories is to link up an oscilloscope and get some one to drive the vehicle in order to capture the data.From your description it does sound like a turbo over boost scenario where the vanes are sticking or fractured causing an over boost and therefore shutdown to protect engine from damage,but only testing will prove it.

Thanks to those who replied. Yesterday I drove the car after the four injectors had been changed - tank empty so first drove the car from a cold start from the dealer to a filling station - still a rough idle and misfire/cut-outs over 2000rpm. Brimmed the tank with clean fuel, started up, smooth idle, and then drove a fast 5 miles over a twisty road, up and down the rev.range - car like new again. Thought I'd cracked it.

Then turned round to go back to the dealers - rough idle returns, along with the misfire,cutting out, and occasional violent over-revving when foot is off the throttle when changing gear. Back to the drawing board .....

Thanks to BustedKnuckles for the sticking turbo vanes suggestion - but would it also cause the soaring over-revving ?

Dealer trying their best but mystified. Skoda UK not really interested - I was thinking of buying a Yeti, but they can now forget that.

Colin.

hi colin

i have seen this quite a few times

i agree with bustedknuckles about the possibility of the turbo vanes sticking . if the turbo vanes are stuck in the full boost position this will cause the turbo to over boost and the car goes in to limp mode .by going in to limpmode the engine rev's will drop to stop any engine or turbo from damage .
this has probably been caused by either faulty injectors ( which you have now changed ) faulty egr valve ( sticking ) or oil in the intercooler , so you need to clean and pressure test the intercooler and clean / replace or blank your egr valve .this will make sure it will not happen again .
ps: there should be no oil in the intercooler ( at worst a little vapour / mist of oil ) when the intercooler has enough oil in it that the turbo pressure can force it out of the intercooler and in to the inlet manifold , then on top of the piston , the engine can RUN ON its own oil (cause engine revs to go up on its own )
if when all this is done you still get the same or similar problem , then you are left with the turbo ( turbo vanes sticking ). most turbo company's now offer a repair or fully remanufactured service,
so you might get away with just changing the turbo vanes ( vnt ring ).

1/ check oil in inter cooler
2/ check egr valve
2/ check turbo / turbo vanes

hope this helps if you need any more info let me know

thank you
turbo-vanes.com

yes i have got a turbo business but its not open yet !

hi

if you would like more information check out
our website http://turbo-vanes.com/

thank you

Eventually we have the car back on the road - thanks to Tim at AVW in Caernarfon. His initial thoughts were that the ECU might be faulty - sent away for testing, and came back 'no faults'. So he persisted with the fuel system, including replacing the supply pump which was a little low on pressure. Still no change. So we sent the ECU away again to another tester, ands again it came back 'no faults' . Tim wasn't convinced, so he shelled out on a £6k machine which allows him amongst other things to switch ECU's between cars - the immobilisers prevent this being possible without being able to temporarily re-programme the ECU. Then he had to wait until he found a car with an identical ECU - with the customers permission he switched ECU's between the cars, and hey presto - the fault transferred between cars with the ECU. So, we ditched the old ECU and replaced with a used £400 one - new ECU price would have been £1350. Car now back in good health, - thanks to Tim and his team.