Lumpy idle when started cold

[flames7607]

Hi Everyone



2003 1.9Tdi, PD engine, 90k miles

Two problems

1. Misfiring when pulling in 1st and 2nd

2. When starting from cold, engine ticks over with an intermittent stutter/misfire until the engine is warm, accompanied with dark blue smoke from the exhaust, which coincides with the stutter/misfire

I've solved Problem 1 (hopefully) by fitting a new injector wiring loom, but Problem 2 persists.

I hooked up VAGCOM and there are no fault codes, however the readings on Measuring Block 13 seem a little strange. Cylinder 1 is always much higher than  the other 3. Regularly over 2.0 during the misfire. Whilst it's still within what VAGCOM says it should be (-2.8 to +2.8) the other cylinders have much lower readings. Am I right in thinking that the high reading is associated with the misfire ? When the engine has warmed up the misfire goes away, and all the readings on Block 13 are all low.

Also, in Block 4, (Unit injector valves command) box 2 reads 4.3 BTDC and box 3 reads 5.1 CF. I'm not sure if those readings are relevant

Clutch in or out doesn't make any difference.

Any suggestions gratefully received

Cheers

[johnnyroper]

I wonder if you have an injector that is leaking slightly after being parked.

If it was me I would take glow plugs out put some clean rag over holes and with injector loom disconnected spin engine over when cold and see if any fluid is ejected from the cylinder. I would also be doing a compression check if nothing comes out in first test.

The injector deviation is not necessarily an injector problem it just gives an indication in to the overall health of the cylinder.

[SirDavidAlhambra]

If you give it a dam good revving up in the morning after starting it up, does that clear the oil out and put it back to normal again?

Now, some questions.

Are you sure it is blue smoke madam (not white)?

Does said vehicle use oil? Does the dipstick level go down over time?

Have you tried changing the glow plugs (this would mainly be needed if the smoke was in fact white)?

Failing that, might it be the valve stem seals madam? Rumour has it that the PD engine has vertical seals and oil leaks past if theyââ,¬â,,¢re not tight.

Thank you.

[Chrispb]

The readings you show for block  4 is that when engines hot? box 3 should be 5 to 8 so that's OK. more importantly what is box 4 showing, this is the fine setting for the engine timing this should be as close to 0.0 when hot as should box 2, 2BTDC to 2ATDC if the latter is not the case when hot your timing is slightly out.

[flames7607]

Hi everyone,

Box 4 of Block 4 shows 0.0 when hot, so I guess the timing is correct. The smoke is dark blue, verging on black, so I'm thinking fuel. It definitely doesn't seem to be oil burning. The car doesn't use any noticeable amounts of oil.

I will try the other suggestions and report back

Cheers

[SirDavidAlhambra]

Could we be talking leaking turbo hoses here, if the smoke is a bit on ze black side?

Thank you.

[flames7607]

Don't think so. Vehicle is not down on power, and only has this problem at idle, before it's warmed up a bit, (and I do mean just a bit. Once coolant is up to about 35c it's gone away

[SirDavidAlhambra]

Hmm, tricky one. Have you tried using slightly thicker oil in the car, might that help perhaps? I had a Peugeot 405 once which positively drank oil until I put some 15w40 in it.

[johnnyroper]

Donââ,¬â,,¢t use anything other than the recommended VW spec oil in a PD engine as the cams take a pounding.
Turbo hoses wouldnââ,¬â,,¢t cause an issue like that,you would get noise and plumes of black smoke under acceleration if one of them was split

[SirDavidAlhambra]

How common is it for garages to use the wrong oil please? Iââ,¬â,,¢m always very nervous when I take my car for a service because Iââ,¬â,,¢m worried theyââ,¬â,,¢ll use the wrong oil. Thank you

[flames7607]

Could it be a glow plug failed or failing ? Would that show up in VAG COM ? Can you test for it using VAG COM ?

I've followed the guide on here to test the resistance for the plugs, and am getting one cylinder giving very different readings to the other 3, however I'm grossly incompetent at using a multi meter ! I set the dial to the highest level, and was getting readings around 800-950 on 3 cylinders, but one would not give anything other than 1 (the default reading)

I'm thinking that if one cylinder is not getting heat from it's glow plug it would misfire, fuel from that cylinder would be pushed out of the exhaust, and engine would run rough. Once the other 3 cylinders had heated up the misbehaving one, it has enough heat to burn the fuel, and hence the problem goes away ?

Thanks

[flames7607]

I've also noticed that the pipe to the vacuum chamber (big ball in front of the engine) has broken off where it enters the ball.

I see from the site that this is used in various systems - but what systems ?

[brianh]

How common is it for garages to use the wrong oil please? Iââ,¬â,,¢m always very nervous when I take my car for a service because Iââ,¬â,,¢m worried theyââ,¬â,,¢ll use the wrong oil. Thank you

If your that concerned about the oil used, the best thing to do is change it yourself, then you know whats been used.

[johnnyroper]

Looks like one of the glow plugs has failed then however I wouldnââ,¬â,,¢t think that would cause the issue you have in current temps. The PD is very good at cold starting without glow plugs unless very cold.

The ball you refer to is a vac reservoir itââ,¬â,,¢s main purpose is to store vac so certain tests can be performed with engine  off using vcds. It wonââ,¬â,,¢t cause the lumpy idle and smoke. Needs fixing though as turbo,egr and anti shudder are vac controlled so if itââ,¬â,,¢s broke it will be losing vac. I did away with mine and went with simplified vac hose set up. As a test you could just blank the vac hose off so it canââ,¬â,,¢t leak vac.

[SirDavidAlhambra]

I had a rough idle on my diesel Ford Focus (very slow car but fun to drive) and changing my glow plugs cured it. Why not give it a go, especially if it looks like one of them has failed anyhoo. Thank you

[flames7607]

Thanks everyone, I will change glow plugs and vac bottle, and do some more testing. will try and video the smoke etc . .

Watch this space :-)

Cheers

[SirDavidAlhambra]

Thank you. Looking forward to the video, always enjoy that sort of thing.

This evening I plan to get my car ready for the winter

[johnnyroper]

Thanks everyone, I will change glow plugs and vac bottle, and do some more testing. will try and video the smoke etc . .

Watch this space :-)

Cheers

Go careful with the plugs they can seize in solid,good spray with plus gas day before. Warm engine up and gradually unscrew with 1/4 drive socket set. If they go tight backing out slightly tighten up and then back out again. Keep doing this will minimise chances of breaking them.

Personally donââ,¬â,,¢t think that will be your smoke and lumpy idle until warm though,with knackered plugs any lumpy running and smoke quickly clears rather than staying until itââ,¬â,,¢s warmed up.

[flames7607]

SOLVED, SOLVED, SOLVED !

So I took out the 2 suspect glow plugs - they both had a resistance of 850 !

I replaced them with 2 new ones (Bosch), and tried starting the vehicle first thing in the morning and hey presto, smooth running from the get go. No smoke, no misfire/lumpy running. I connected VAG COM, and the readings in block 13 for all 4 cylinders started as  + or - 0.5, and after a few minutes settled to 0.2 !

So, all in all, a successful fix.

Thank you everyone for your help.

Cheers

[johnnyroper]

Nice one,I am surprised though that was the problem in the current temps.

[SirDavidAlhambra]

Thank you, I'm pleased you have cured the problem by changing the glow plugs.

I had just that problem on my Ford Focus and the glow plugs were indeed the culprit.

A lot of people say that the glow plugs are only really used when starting a cold engine, but in my experience a good set of glow plugs helps all year round.

Well done! A nice, cheap, easy fix. I bet some garages would have charged tens of thousands to diagnose that! (I once had a garage advise me to replace my steering rack in order to fix a problem with the rear speaker).

A very pleasing outcome indeed. Here's to the Forum! Cheers! 

[flames7607]

Indeed, thanks once again to everyone for their help :-)