Car does not sound good

[scarr89]

On starting, only noticed this since the cold weather has really set in, the car does not sound healthy. TBH I don't know what a misfire sounds like, but I guess a mis fire sounds like my engine. Revs dont go up/down, stay at about 900-1000.
It sounds as if the engine runs fine for a second or two and then goes lumpy for a less than a second then runs good for a second or two then goes lumpy etc etc. It does this for maybe 30secs to a minute on start up, then goes away. If I drive off within say 10seconds of starting the problem does not persist if I stop a junction, then on my return journey from the shops say when I start her up there would be no issue...

I have no EGR valve and have done the vacuum simplification, 150PD.

I Would really appreciate any help at all!

[Agreeable Slick]

I would really appreciate some help yes, but that's another topic.

It sounds like a glow plug needs changing, get it on vagcom and it might throw up which one, but better off just changing the lot. With the cold weather the plugs are used for longer at start up and all the symptoms point to the cold starts asking too much of a poorly plug or two.

[scarr89]

I would really appreciate some help yes, but that's another topic.

It sounds like a glow plug needs changing, get it on vagcom and it might throw up which one, but better off just changing the lot. With the cold weather the plugs are used for longer at start up and all the symptoms point to the cold starts asking too much of a poorly plug or two.

Atleast you noticed my error...I'll change that ASAP

Makes sense I guess. I thought glow plugs were just used to start the engine, rather than stay on to provide continual heat once the engine is started? If there was a faulty glowplug would the remaining X amount still be able to get the engine going?

[Agreeable Slick]

You are correct, they only come on to start the engine, usually only a few seconds, however with colder weather the plugs stay on longer. If the engine has stood over night then the surrounding environment would be an ambient of lets say 0 degrees, a diesel relies on there being enough heat within the compression stroke to ignite the fuel/air mix at just before tdc. If the surrounding cylinder walls are all at 0-1degrees then the charge requires a lot more heat to warm it up, thus the plugs stay on longer to help it out.

You can do a very rudimentary test by starting from cold, letting it run for a minute, switch it off, then start it again and see if the same happens. It shouldn't unless it is very VERY cold.

[scarr89]

Understood. Thanks alot.

I'm heading home this weekend, I'll get it hooked up to the lappy, and vagcom will defo tell me if a glow plug is out right?

Thanks again.

[Agreeable Slick]

It might do, I've never had need to check on VAGCOM for it though, so couldn't tell you for definite.

For the effort it will take you, you might as well change the lot (I think they only sell them in 4's anyway) and have that extra peace of mind.

[scarr89]

After a short journey, and a rise in temp from first thing this morning the car started perfectly without the issue described. I'll check it out on vagcom and see if it the glow plugs. I'll probably change them any how...don't know when they last were!