New glow plugs fitted but still doesn't start well

[bigmac1]

Hi I've got a 07 vrs tdi, I've had it about 2 months and when first had it, it started fine. Then the EML came on so had it plugged in. Came back with no.4 glow plug. Had the set changed and found the tip on no.4 had broken off in the head. Luckly managed to get the broken peice out. So with a new set of plugs it should start well but it does struggle. Tried running the new plugs through 3 heat cycle before trying to start but no difference. Also when it does start the revs are stable but the engine feels lumpy. You can feel it in your back through the seat.

Any idea's people?

Edited 13 November, 2013 by bigmac1

[Ultrasonic]

(I'm not a mechanic so this is very much an amateur suggestion.)

 

How old is the battery? A new one may help with starting but will do nothing to help the 'lumpy' feel (not quite sure what you mean!), but this can't have anything to do with the glow plugs either.

[wagonwheels]

I solved poor starting with a coolant temp sensor but may not be your fault.Wonder if the coolant temp sensor triggers the glowplugs via the ecu? Maybe talking rubbish though

[bigmac1]

The battery was replaced 2012 and is good. I know this because I parked the car up for 2 weeks after bought it and it started first time. I would say the poor starting has been since the the EML light came on and the glow plugs changed. The lumpy ness I mean is as if there is an imbalance or a misfire if that's possible on a diesel?

[nickguzzi]

Looking at the bad end of failure modes first, poor starting in a Diesel could be the result of poor compression.  

The glow plug circuit used to be activated for a while after firing to speed warm up and reduce rough running.  Several possibilities there.  Sensor, control unit, wiring etc.

Have a look with VCDS, to make sure everything is reporting present and correct and ready for duty. 

[bigmac1]

It seems weird that I only noticed a problem when the EML had been on. You mentioned about cylinder compression, it's possible that a small peice of no.4 glow plug came away when it broke and has done some damage to a valve.

That's worse case sanario. Would VCDS record cylinder compression? Or pick out one that wasn't performing?

[cheshire_cat]

I solved poor starting with a coolant temp sensor but may not be your fault.Wonder if the coolant temp sensor triggers the glowplugs via the ecu? Maybe talking rubbish though

on some systems the ecu keeps the "afterglow" on 'till the water temp hits 70'C

[bigmac1]

Thanks for the reply's the car had been stood for 2 days and took an age to start this morning, the worst it's been so far and it wasn't even a cold morning. A kind briskoda member it putting vcds on tomorrow. The car won't be cold but hopefully will have logged something that might shed some light on the situation

[bigmac1]

Right had vcds scan done and no faults were found. I can't seem to escape the fact that everything was fine even with EML light on. And the problem has only started after the new plugs have been fitted. Are coolant temp sensors expensive? And how easy to fit?

[Guest]

A dodgy preheat relay perhaps?

[erindad]

I'm assuming its the same engine as a vw Passat, it needs the coolant temp sensor to trigger the glow plugs, faulty sensor = no glow plugs heating .

 The sensor signals the ecu as it thinks the engines warm so doesn't need glow plugs heating.

 

Then again it may be the wrong plugs.

[cheshire_cat]

OK -- something that hasn't been mentioned but playing on my mind over this --are the glowplugs that you put in actually the correct ones for your engine code??? They might differ in temperature output, voltage, or resistance. Check the invoice from when you replaced them, and failing that, for the sake of £40 before you start spending loads on other stuff, would it be worth changing the complete set of glowplugs again, checking they are the exact ones for the car?

 

If you check the ebay listings for the glowplugs you'll see that they are different for the PD and non-PD engines. They may physically fit but will not work properly if they are the wrong ones.

 

Mike

I remember a few years back the yanks were spending a lot of time and trouble with golfs on FREDs   the wrong replacement  plugs being fitted  I'd be checking info from several sources 

[radders567]

I agree. You would need to check and make sure the glow plugs that were fitted are actually the correct ones.

 

Other things to consider for lumpy tick over are

 

1. Wiring in the cylinder head.(This does not usually show up a fault on VCDS for the ones I have changes to improve tickover)

2. Worn cam lobes (read poor fuel economy, poor starting, lumpy tick over, possible X S smoke on hard acceleration etc).

 

Hope this helps

[bigmac1]

Checked the gsf website and it states that ngk 9835 plugs should be fitted. Just checked the parts invoice and it just says part number 9835 glow plug. When I get chance I'm going to whip the rocker cover off and have look

[radders567]

If you have access to VCDS you could check the water temperature sensor to make sure that is not giving / causing trouble. They are quite inexpensive and easy to fit, although a tad messy.

[rogerzilla]

Unless it's seriously freezing (as in -10 or below), a direct injection diesel makes enough heat through compression, even when cranking, to start the engine.  On many cars the glowplugs won't even be energised above about 7 deg C.  This isn't like the obsolete indirect injection diesels (Peugeout XUD etc) which really needed the glowplugs to heat the pre-chamber.

 

Normally the injection timing is advanced for starting and the ECU may also inject a bit more fuel than normal, so more is happening than just the glowplugs.  I would suspect the temperature sensor.

[radders567]

Once again though this can be monitored through VCDS

[bigmac1]

Noticed the lump tick over is worse the colder it is. Could this be the DMF?

[bigmac1]

Mine runs lumpy after being driven. Started from cold tonight drove 3min round the corner and pulled up and it was really lumpy.

[bigmac1]

Any updates guys?

[drw8]

How are you starting the car? Dont own a diesel octavia, but I did own a diesel focus and you had to "pre-heat" the glow plugs i.e. ignition 2 clicks forward, wait for the glow plug symbol to extinguish and then start the engine.

[bigmac1]

Came to start the car this morning expecting the normal prolonged cranking but no. She fired up straight away, still had the lumpy tick over. Then I came to start it just after it had been parked all day and prolonged cranking was back.

It has got to be a dodgy sensor give duff info to the ecu about injection timing and air to fuel mix.

I've read plenty of posts from people with similar symptoms but never a cure

[silver1011]

Let me guess, it's had the injectors replaced recently (official Skoda recall)?

 

Poor cold starting on the PD170 is very well documented on here and other VAG forums. Plenty of threads but this is one of the most recent...

 

http://www.briskoda.net/forums/topic/189502-cold-start-problems-with-a-pd-tdi-170/page-1?hl=+poor

 

I had the same issue (watch the video's I posted on the above thread).

 

Despite more than 25 days with the dealer they never managed to fix it, even after plugging my car into Skoda in the Czech Republic via the internet!

 

Had a new battery, glow plugs, injectors, various sensors etc. They even adjusted the timing. Sold it in the end, was doing my head in.

[bigmac1]

Hi silver, yes I had already read your other thread. I'm not sure when the injector recall was done but it's wasn't this year. It started fine when I bought it and until the EML came on. Like you say it's really annoying

[silver1011]

Mine wasn't so bad during the summer and autumn, it was only when the first frosts arrived together with being stood in the cold and damp winter air during the day that I noticed the issue. Come spring normal service was resumed.

 

There should be a sticker in the boot next to the spare wheel well with the recall code and date printed on it.

 

My dealer acknowledged the problem but Skoda UK and the dealer turned round to me and admitted they were stumped and that nothing more could be done, basically washing their hands of me.

 

Good luck, I hope you are the first to find a fix!