Help diagnostics can't find fault

[Faulder]

Hello

 

We have a 2009 Skoda Octavia 1.6 TDI which has been brilliant until last year, when an intermittent fault started.

We have put the car into firstly and independent garage and a Skoda dealership to try and get the problem cured to no avail. 

 

Symptoms:  Please remember these are intermittent and it may go a day without doing it.

 

Without touching any pedals when idling the car will cut out.  It sometimes starts again straight away but sometimes takes several attempts.

Whilst driving and accelerator has been released on reapplying accelerator the car looses rather than gains power; if at high enough speed changing down to pick up the revs will usually regain power.

Whilst driving the glow-plug light flashes with no other warning lights but the car does not go into limp mode as described in manual.

Idle speed varies sometimes its about 970-980 sometimes its 850.

Skoda dealership have done several diagnostics scans but unable to definitely diagnose problem.

 

Garages have replaced coolant temperature sensor, air flow sensor.  Yesterday a software update for a suspected "egr operation issue"

We picked the car up but problem re-occurred after a couple of miles.

 

My thoughts are:

To replace the accelerator unit.

Replace the boost pressure control solenoid (N75)

Replace Brake Light switch 

 

I am not familiar with common rail diesels could someone tell me if there are any mechanical linkages involved which may have developed backlash? 

 

Any help please!

Edited 4 March, 2014 by Faulder

[KenONeill]

Well, the variable idle speed makes me think of the throttle position sensor (part of the pedal assembly; may need an entire pedal) or the idle stabilisation control.

[Faulder]

Thanks for the reply.

 

what is the idle stabilisation control?

[Eddie-NL]

Change the accelerator pedal, if you don't have aluminium ones now is the ideal time to upgrade.

 

if you need help i know someone in Dundee that could do it

[Faulder]

The "master tech" at the Skoda garage tells us it is the EGR cooler/valve 

£750 to replace.

Hope it works!!!!!!

Thanks for help

[kerrymarkp]

Hi Foulder

I know it was a while ago but...

Was it the EGR that needed replacing? I have similar problem

Cheers