Hi Everyone,

Octavia 2002 1.9TDI

So I've looked through all the pages on glow plugs, white smoke, grey smoke, temperature sensors etc and still haven't figured what could be up.

What happens is:

Cold temp (we're in Switzerland so sometimes to -10 degrees) glow plug light comes on for about 2 seconds then goes off.

Sounds fine and dandy BUT then the motor wont turn start. If I turn the ignition 4-5 times then it will start and run roughly almost straight away, 2-3 times and it needs a bit of cranking over before it starts. It helps if I give a bit of gas whilst cranking. After both there is grey smoke and it runs rough for a while.

So what have I done already. Tested battery at night and in morning both a healthy 12.48ish V with lights turned on.

Heard the relay clicking in and out as the revs go above 2500 and then below, whilst parked and driving.

Checked ALL the fuses (way too many!!)

Plugged in VCDS lite. ****ed about a bit as I don't really know how to use the program. But found the thing to measure the glow plugs. it said the glow plug period was 2.1, a whole bunch of 1's and 0's at the beginning don't know what they are. The outside, inside, coolant temp etc all looked in order.

How long should the glow plug light come on for when it's cold? (I had imagined even with one to possibly four stuffed glow plugs it would be on longer than a couple of seconds)

Why when we bought it about a month ago with the same cold temp did it not have a problem starting? (really what could have died since then)

When I take out the glow plugs what should I look for to see if they are no good?

Is this problem starting causing long term damage?

Thanks for any and all help.

PS is there a guide on how to use vcds lite for octavia's anywhere

CHeers

Fraser

My glow plugs stay on much longer than 2 seconds at -10C. Could be your temperature sensor. Easy to change. Search on here where there are many threads and guides.

Wouldn't that show up in the VCDS temperature information? everything under temp seems to be OK

Do diesels have an electric fuel pump?

ie will turning the ignition on cause the pump to prime?

Just wondering if it's a fuel related issue?

Sent from my Galaxy S3, not a Crapple!

diesels don't self-prime (at least not when you change the fuel filter).

The relay click around 2250-2500 rpm is the glowplug relay. My initial through would be duff glow plugs, or faulty wiring maybe?

I have never looked for/at the glowplugs on my 110TDI, but I wonder if you might be able to disconnect and check the resistance on them (to determine if they have failed and gone open circuit), and then with the ignition on / seconds after starting that you seeing +12v across them all.

Could be an issue with the glow plug relay or 109 relay, have you changed the coolant temp sensor - what colour is the one fitted?

Also timing will cause starting issues.

Assuming its not a PD engine there isn't a electric fuel pump, just the injection pump attached to the engine.

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also are all the fuses on top of the battery ok?

diesels don't self-prime (at least not when you change the fuel filter).

The relay click around 2250-2500 rpm is the glowplug relay. My initial through would be duff glow plugs, or faulty wiring maybe?

I have never looked for/at the glowplugs on my 110TDI, but I wonder if you might be able to disconnect and check the resistance on them (to determine if they have failed and gone open circuit), and then with the ignition on / seconds after starting that you seeing +12v across them all.

Haynes recommends measuring the resistance across them too. Bit of a small finger job. Will try it tomorrow. Interested in the wiring thought tho. I had expected that a fault would show up when resistance/voltage was wrong... don't know the capabilities of the diagnostic program.

Thanks

Do diesels have an electric fuel pump?

ie will turning the ignition on cause the pump to prime?

Just wondering if it's a fuel related issue?

Sent from my Galaxy S3, not a Crapple!

There must be some sort of pump somewhere, it's an injected engine so it has to have some form of pressure as trundlenut said. It's been serviced in a Skoda Garage here in switzerland regularly I ASSUME they would change the fuel filter at set intervals. i should be able to check the paper work for that.

If its an issue with the injectors then bugger it I'll live with the rough starting when it's cold.

Thanks

Could be an issue with the glow plug relay or 109 relay, have you changed the coolant temp sensor - what colour is the one fitted?

Also timing will cause starting issues.

Assuming its not a PD engine there isn't a electric fuel pump, just the injection pump attached to the engine.

Sent from my Nexus 4 using Tapatalk 2

So I haven't changed anything yet. Parts out this way are expensive so I'm trying to whittle down to the most probable cause and then will order it from the UK

Will check the colour of the coolant temp sensor. Which colours are bad?

The timing check on the diagnostic program said that the timing was ok. There were two timing boxes, not sure what thats all about tho? Or am I being stupid and thats when the FUEL was being injected not actually to do with the valve timing. Hmmmm

Could be something there. Is timing usually a cause of black smoke when giving full throttle??

All the fuses are fine.

Thanks for the thoughts

Still wondering if the short glowplug light is relevant to the relay or to the coolant temp sensor because the glow plugs are still turning on which wouldn't happen when the CTS read above 9degrees....

you want a green CTS, rather than original black ones. CTS image

I am not 100% sure, but I think the timing for the glowplugs is pretty simple. Along the lines of:

- is it below 4 deg C, then turn on glow plugs for 10 seconds

- is it above 4 deg C, then turn on glow plugs for 2 seconds

I make up the temperature and duration, but you get my drift. Also when cold, then glowplugs will come on at low revs for the first few minutes of driving too (the relay click you hear).

I don't believe that the car monitors the resistance/state of the glowplugs. However you (as the driver) provide the monitoring by the basis the car starts badly....

Edited 5 March, 201313 yr by mbames

you make a good point! head under bonnet tomorrow.

Cheers

What mbames said. Also if you unplug the CTS then the glow plugs should stay on for the maximum amount of time. You just need to undo the wiring plug on the sensor.

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Sorry to nick this thread,but my skoda octavia vrs 53 plate runs rough in the morning on.first start up, seems to splutter like its missing,just had my.coil packs done yesterday 7/3/2013 as i thought it maybe that but still doin it. Its ok when warmed up and running tho any ideas would be great thanks.

So just to close the thread.

I unplugged the CTS and voila the glowplugs went on for max time and it started beautifully..

It has a GREEN sensor. Is this a bad one?

Just to summarise for people looking through the threads for similar issues.

VCDS readout & the gauge on the dash showing the correct temp DOESN'T mean the coolant temp sensor isn't buggered.

If the glow plugs don't go on for longer than a couple of seconds by cold temps, even if the relay clicks in and out then probably the sensor is faulty.

If the relay isn't clicking passing 2500rpm then check that first. The relay is in the area under the steering wheel.

There are fuses for the glowplugs on the side of the dash AND on top of the battery.

It's not so easy to unplug the sensor. Do not pull out the retaining clip as you will then pull out the entire sensor and lose coolant

If you don't have time to replace the sensor then unplug it start the car and plug it back in again... works like a charm.

Cheers for the above help

Now just gotta figure out why the driver seat heating is working....

The green she sensor is the new type actually. If it is giving the wrong temperature but in the right range it will likely not show an error. Its pretty easy to change.

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Id recommend replacing it with a genuine Skoda one from dealers. Or Audi or VW, whatever is closer, its all the same part.

Pattern parts here have been known to cause issues.