Skoda Octavia 2, 1.9 tdi 2008  45,000miles

When starting the car while hot, the engine sounds as if the engine fires in the wrong cylinder order, and the engine does not start.  After about 2 seconds of this dicordant sound, it sounds as if one cylinder fires before TDC and thus the engine stops turning abrubtly.  The engine will then start and run normally.  

This has happened 3 times.  After the second time, the engine would not start instantly as it would normally do, but had to be run on the starter for a few seconds.  After it started, it seemed to run ok.

I took it to my local Skoda garage who tested it with VCDS and said the timing sensor had failed.  They replaced it and the car worked well for 3 weeks.  Then today, the engine started again as in paragraph 1, ie sounds like it has fired in the wrong order.  Can anybody help me with the diagnosis?  I have not yet taken it back to Skoda to see if the new timing sensor has failed.

Camshaft sensor, failure again or wiring fault.

 

You can prove it by disconnecting it, its primary use is for the fast start feature, with it disconnected the engine will take another 1/2 revolution or more to start but will then run perfectly on the crankshaft pulley sensor.

 

If the starting is smooth albeit longer then its the sensor and/or its wiring and connections.

Edited 3 April, 20197 yr by J.R.

Hi JR

 

Thank you very much for replying and confirming my fears.  I take it that the camshaft sensor is the same as I was told it was called, ie timing sensor.  I am in Spain, lots gets lost in translation! 

At just shy of €200 to replace, it seems expensive to only be "a fast start feature".  After it was replaced, I felt that the car ran better, and pulled better but these things can just be in the imagination.  It certainly started better.

 

I see you call this car the best and cheapest car ever - I couldn't agree more.  I stupidly moved on to the Octavia FL with the 1.6tdi engine, what a disappointment it was.  And what a joy to go back to this older but infinitely better1.9.

 

Thanks again.

Update:  I have just been to the Skoda garage to see what they say about this.

 

They looked a bit perplexed and suggested that it might be the toothed belt, that is the timing of the camshaft to the crankshaft might be a tooth out.  The belt was changed 10,000 miles and 1 year ago.  He suggested that it might have been improperly done or that it could have jumped a tooth.  I have never heard of such a thing happening.  And as the car started, and ran perfectly well for the past 10,000 miles, the car is not sluggish and the fuel consumption is normal,  I do not feel confident in their diagnosis.     Also, if this were the case, why would the problem be so intermittant?  They are suggesting that they check the timing, thats 2 hours work and about €90.

 

Any thoughts?

 

 

15 minutes ago, Coinneach said:

 

They looked a bit perplexed and suggested that it might be the toothed belt, that is the timing of the camshaft to the crankshaft might be a tooth out

This I do know about. If the cam timing is that far out, you should have a lack of power, and are probably heading for a can belt tensioner failure.

They are just taking you for a ride, toothed belts dont jump a tooth unless the tensioner has completely failed, if they jump one they will rapidly jump another and lunch the engine, it just does not happen, the belt losing its teeth and lunching the engine yes, the garage fitting the belt one tooth out and engine running like a dog, yes.

 

My advice to you is to do the test I suggested.

 

The camshaft position sensor is not used soley for the quick start system but that system cannot work without it, its used by the ECU but if the signal is absent or implausible it will continue to run using the default crankshaft position sensor.

 

Its all explained in the VAG 1.9 PD engine self study guide.

I am really grateful for your replies, these intermittant faults are really difficult.

 

You have convinced me that the belt is not going to be the problem, I had no faith that it would be.  Seemed illogical.  So I will tke your advice and disconnect the sensor.

Is it easy to disconnect the sensor?  Where can I find the VAG 1.9 PD engine self study guide.  Never heard of it but it sounds as if I should read it!  Tried googling it, couldn't see an obvious download.  Do you have a link?

 

Thanks

56 minutes ago, Coinneach said:

I am really grateful for your replies, these intermittant faults are really difficult.

 

You have convinced me that the belt is not going to be the problem, I had no faith that it would be.  Seemed illogical.  So I will tke your advice and disconnect the sensor.

Is it easy to disconnect the sensor?  Where can I find the VAG 1.9 PD engine self study guide.  Never heard of it but it sounds as if I should read it!  Tried googling it, couldn't see an obvious download.  Do you have a link?

 

Thanks

I downloaded it from ErwinSkoda together with loads of other manuals etc with an hours access for €8

A condensed extract of the info regarding the G40 camshaft position sensor:

 

Hall effect sensor attached to toothed belt guard below the camshaft gear.

 

Function is cylinder recognition when starting the engine (quick start)

 

Engine control module uses info from G40 to determine relative positions of the cylinders and uses this info to controlthe solenoid valves for the pump injectors.

 

In the event of the G40 signal failure the Engine Control Module uses the signal that the engine speed sensor G28 generates.

 

That should help you understand its function and to locate it, it may be loose or dirty/contaminated otherwise disconnect it and observe the effect.