Blue smoke, rough idle - Forscan DTC code

[Albert27]

10 minutes ago, Tdci-Peter said:

If there is no noticeable oil loss, then a cylinder compression test maybe the next easiest test

Thanks Peter.  So the next question for me as a complete beginner; how do i go about performing a compression test and what would i need?

[Tdci-Peter]

1 minute ago, Albert27 said:

how do i go about performing a compression test and what would i need?

It is not so easy on a diesel, as on an old petrol car. It usually needs removal of the glowplugs, applying a test pressure to each cylinder, and either measuring the air flow, or seeing how quickly the pressure falls once the supply is cut. So it probably needs some fairly special kit. I suggest asking around local garages first.

On a petrol car, all the spark plugs were removed, then a simple gauge with a rubber bung was held in each plug hole in turn while cranking the engine. The gauge recorded the peak pressure in each cylinder. This is a bit more problematic on a diesel, pressures are higher, and the peak is shorter. Also it would be advisable to disable the injectors in some way, or quite a bit of fuel could build up in the engine. I have not tried it!

BTW, did you see my edit in the last post about glowplugs, try re-loading that page. I entered it as you entered your last post..

[Albert27]

53 minutes ago, Tdci-Peter said:

It is not so easy on a diesel, as on an old petrol car. It usually needs removal of the glowplugs, applying a test pressure to each cylinder, and either measuring the air flow, or seeing how quickly the pressure falls once the supply is cut. So it probably needs some fairly special kit. I suggest asking around local garages first.

On a petrol car, all the spark plugs were removed, then a simple gauge with a rubber bung was held in each plug hole in turn while cranking the engine. The gauge recorded the peak pressure in each cylinder. This is a bit more problematic on a diesel, pressures are higher, and the peak is shorter. Also it would be advisable to disable the injectors in some way, or quite a bit of fuel could build up in the engine. I have not tried it!

BTW, did you see my edit in the last post about glowplugs, try re-loading that page. I entered it as you entered your last post..

Cheers Peter, I'd missed that.  

Tbh the compression test seems way out of my abilities for the moment. 

I've always discounted the glow plugs because they were replaced by Ford in Feb 2014.  The issue started around Dec 2015 or (30,000 miles later).  I need to bottom out the cold start/cool start thing and temperature.  Is there a guide anywhere for testing the glowplugs?

Are you saying that on a cool start after say an hour, if i get no smoke that means glow plugs ok or the opposite?   Haven't quite understood that bit.

I guess my other question is as follows.  Apart from looking like an earth polluter by the occasional greenpeace activist who happens to be standing near me on a cold start, what happens if i just leave this issue?  Will further symptoms develop to help the diagnosis?  

 

[Tdci-Peter]

17 minutes ago, Albert27 said:

Is there a guide anywhere for testing the glowplugs?

If you can remove them, it is easy. Connect to a car battery with jump leads (carefully!) & see if the ends glow red!

If they are in the engine, a clamp-on current meter can test them. But without this unusual bit of kit, the wires to each will have to be disconnected (often a bit fiddly), then they can be tested with a multimeter, and should read virtually short circuit, under 1 ohm. This is not a full test, but is usually good enough.

24 minutes ago, Albert27 said:

Are you saying that on a cool start after say an hour, if i get no smoke that means glow plugs ok or the opposite?

After 30 minutes to an hour, pistons & injectors will be at engine water temperature, which will be about 50C to 60C, probably. If it starts rough with smoke at this sort of temperature, then that would virtually rule out Glowplugs. It leads more to compression problems.

If it needs an overnight stand to get fully down to ambient before the problem happens, then as I do not know the temperature at which your car will start without glowplugs, I can not eliminate them. Though it is very rare for any common rail diesel to need glowplugs at engine block temperatures above about 15C. The high fuel rail pressure and small droplet size give better starting than older diesels.

The 15 to 30 second time scale is what makes me think of piston temperature, they heat up quite fast to some 200C above the engine block temperature, when it starts. And they will cool equally fast down to block temperature when it stops. So I would expect most compression problems due to cold to kick in quite soon after stopping. Though oil draining back to the sump would take a bit longer, and can also cause problems initially, that disappear soon after the engine starts & oil is sprayed into the cylinders.

I am just looking at possibilities here really! The basic fact I am using is that Diesels only need fuel & compression (plus a bit of extra heat when cold), to start & run. You seem to have fuel, as you can smell the stuff. So that leads me to compression as a primary suspect.

Does it take extra cranking time when it starts badly? I ask that as I just thought about fuel. It does need to be the right pressure, if it was not rising fast enough, then that is another possibility. And Forscan can measure that one.

 

[Albert27]

6 minutes ago, Tdci-Peter said:

After 30 minutes to an hour, pistons & injectors will be at engine water temperature, which will be about 50C to 60C, probably. If it starts rough with smoke at this sort of temperature, then that would virtually rule out Glowplugs. It leads more to compression problems.

I will run a test in the next few days.  How long should i run the engine for before turning off and leaving it 30mins to 1hour?  Or should i just take it for a good 15 minute blast to warm it up?  I think access might be tricky on one of the glow plugs but i have a volt meter and i know where the glow plugs are having been poking about by the EGR valve recently.  Sounds easier than Haynes prediction of 4* difficulty.....i can only try and hope for the best!

 

11 minutes ago, Tdci-Peter said:

Does it take extra cranking time when it starts badly?

No extra cranking, fires up well regardless.

 

12 minutes ago, Tdci-Peter said:

I am just looking at possibilities here really!

Thanks Peter, i very much appreciate it!

[Albert27]

Peter, just as a side note, when i originally had the glowplug issue and ford replaced them, the MIL light came up and the car went into limp mode.  I've not had this with the current symptoms but would this always happen?

[Tdci-Peter]

2 hours ago, Albert27 said:

How long should i run the engine for before turning off and leaving it 30mins to 1hour? 

It is probably best to do it after a run that warms the engine up to normal operating temperature, then you have a known temperature at the start of the time.

The lack of any extra cranking eliminates many fuel pump or air in fuel type of problems.

It sounds like it is firing up on 3 cylinders, and for some reason one cylinder is getting fuel, but not firing properly, until it warms up.

Some 1.6TDCIs do light the MIL on bad glowplugs, they must test for the current draw, either once the engine is running via the charging system, or via a glowplug module. Do you know how many plugs had actually failed when the MIL came on? If it was multiple plugs, then maybe the system can not reliably detect one failed plug. If it does it via the charging system, this would not surprise me, because the glowplug current varies a lot as they warm up, and detecting 1 fail in 4 by a rather crude method may not be reliable.

If you can disconnect any plugs, you could test whether having any one not connected puts the MIL on. And whether it affects starting. Disconnect one, check it for resistance. If it has any measurable resistance with a normal DMM then it is duff, and needs replacing anyway before Winter. If it seems ok, try a cold start with it disconnected.

Then if the symptoms are the same, possibly apart from a glowplug DTC, then it eliminates glowplugs. If one out causes the rough running, two out should make it terrible.

Or if the symptoms get worse, then you need to investigate the rest of the plugs.

I am still slightly hoping it is plugs, as compression problems may not be good news!

 

 

[Albert27]

10 hours ago, Tdci-Peter said:

Do you know how many plugs had actually failed when the MIL came on?

Unfortunately not but I know they replaced all four.  That might have been to save me further costs had they just done one or two and then the others had failed.

Ok plan of action then is as follows.

• Cool engine start test after 30 mins - 1hour.  No smoke means glow plugs could still be the fault (if I've understood correctly!)
• Test the glow plugs with a voltmeter etc (I'll probably start a new thread to get some advice on access etc on the DV6)
• Depending on above result, get a compression test done (I have a good local garage).  Would a compression test also identify if it was Valve stem seals rather than the piston rings?

And i guess my last question is, supposing it is the worst and it is either the valve stem seals or piston rings - how much are we looking at to replace at an independent garage?

 

[TomsFocus]

Due to the way the plugs are wired on the DV6, when one fails, the others get stuck on so burn out as well.  I thought my multimeter was broken when I tested mine after getting the 'engine malfunction' message and limp mode, no resistance at all on any of them!  I must admit, I've never seen blue smoke from dodgy glowplugs though, usually white if you're missing on one cylinder.   Mine failed in a cold and wet September 2015, engine started and ran perfectly with no plugs at all, slight whisp of grey smoke on first start but cleared in a couple of seconds...only issue was it was stuck in limp mode so struggled to hold 70mph uphill lol.  

Access to glow plugs is the same as EGR, just remove the wiper arms and both scuttles.  

With your mileage, I would expect the inlet manifold to be well coked up with EGR sludge and breather oil.  I wonder if this oil simply drips down onto the inlet valves and is then being burnt on cold start, over-fuelling slightly to give the rough idle and the blue smoke.  Wouldn't be enough to notice while running or after a short stop, but could build up over time.  That's purely a stab in the dark though!

[Albert27]

2 hours ago, TomsFocus said:

Access to glow plugs is the same as EGR, just remove the wiper arms and both scuttles.

Thanks Tom.  I'm assuming to test them in situ I remove the electrical wires/ cover and literally place the positive voltmeter cable on the tip of the glow plug and the negative lead to earth and turn ignition on for a reading.  Then as Peter said looking for about 1ohm resistance.  Repeat on all 4.  Did you find any difficult to access?  Haynes suggests one is very tricky.

[TomsFocus]

Haynes suggests everything is tricky!   I needed to loosen the EGR cooler to remove one of the plugs, not sure if that would also apply to testing in situ.  I also needed to buy a specific glow plug socket to remove them as my deep socket wasn't deep enough but if you're not removing that won't be an issue.   

I didn't bother testing mine in situ, FORScan showed there was a fault with them.  I watched them livestream on FORScan and noticed they were permanently stuck on (should cycle when cold running).  Then tested the relay which worked fine so assumed it would be the plugs themselves at fault without going to the effort of removing scuttle panels.  It was only afterwards that I tried to test them.

Are you testing for voltage or resistance?  Looks like you've got two tests mixed if I'm reading that right.

Voltage test - cables off - ignition on - multimeter (volts setting) one on glow plug cable and other on any earth - should see voltage cycling on and off every few seconds.

Resistance test - cables off - ignition off - multimeter (ohm setting) one on tip of glowplug and other on securing 'nut' of same glowplug - should see some resistance.  No sure how much but if Peter said 1ohm I would trust him.  If there is no resistance at all the plug is dead.

[Tdci-Peter]

3 hours ago, Albert27 said:

Then as Peter said looking for about 1ohm resistance.

The pictures below show tests on a couple of glowplugs. (I can embed photos in the text, but only if they are already uploaded somewhere, I have not worked out a quick way to embed them in the current post!)

GLOWPL0A (2nd photo) is a meter test, just the meter clips linked together, to check meter and cable resistance. GLOWPL1 (top photo) is a duff plug, reading about 40 ohms. GLOWPL2 is a good plug, reading under 1 ohm.

GLOWPL3 got a bit carried away. Nearly set fire to my work bench! I hooked up a couple of power supplies to it, to get the 10A or so it needs to heat up. Note the separate connection for power and meter. This is so the meter gives an accurate reading of the plug voltage, without the dodgy croc-clips affecting it. (Called a Kelvin connection, google it if interested!)

The whole end is glowing bright red in the photo (looks white). And the bench underneath is starting to char and smoke. Just as it started glowing, I looked away to adjust the camera or power, and when I looked back it was really hot! The meter is indicating 10v in the photo.

If the plug is in the car, it needs the wire removing from the top, and measure resistance from the top of the plug to a good earth on the engine.

[TomsFocus]

1 hour ago, Tdci-Peter said:

If the plug is in the car, it needs the wire removing from the top, and measure resistance from the top of the plug to a good earth on the engine.

Not sure I agree with that, you'll end up getting the resistance of the engine block and potentially contaminants in the threads as well?

The plug earth's through its body/securing nut so thats what I'd use for the earth if leaving it in.

You could always try both and let us know if there's a difference!

[Albert27]

4 hours ago, TomsFocus said:

I also needed to buy a specific glow plug socket to remove them as my deep socket wasn't deep enough but if you're not removing that won't be an issue.

Brilliant stuff guys - I'm just soaking all this information in and gradually understanding.  

If they fail Tom, i may want to replace them there and then to save putting it all back together  just to undo it again.  Do you have a link to suitable glow plug sockets?

4 hours ago, TomsFocus said:

I needed to loosen the EGR cooler to remove one of the plugs

Loosened but not fully removed?  Did you leave the coolant pipes on so no loss?

[TomsFocus]

I was in a bit of a panic when I needed them so just grabbed this set from my local machine mart - there are probably cheaper ones available.  Obviously you only need one so may be able to buy singly, I think it was 8mm on these but would want someone else to confirm.

https://www.machinemart.co.uk/p/glow-plug-socket-set-3pc/

Yes the cooler was loosened at the manifold end (torx screws) and one bolt underneath the centre of it, didn't remove any coolant pipes as they're flexible if they were in the way anyway.

[Albert27]

Well guys, just a quick update from the last 24hrs. I've restarted the car 3 times when the engine has been cool and left sat for 30mins - 1hour after a  20 minute - 1hour drive.  On all 3 occasions there has been no blue smoke and no rough idle.   Glow plugs are well and truly a suspect.  Would it be unusual for a glowplug to fail after 2 years/40,000 miles?  That's how long the new ones were in when i first started getting symptoms.  

[GaryPL]

Depends on the types of journeys you are doing.  If your journeys are made up of several short drives a day, requiring the use of the glow plugs each time, then quite possibly.

[Albert27]

2 hours ago, GaryPL said:

Depends on the types of journeys you are doing.  If your journeys are made up of several short drives a day, requiring the use of the glow plugs each time, then quite possibly.

Yes I do a lot of stop start journeys so that would make sense.  I'll be testing them in the next couple of weeks.

[Tdci-Peter]

5 hours ago, Albert27 said:

Would it be unusual for a glowplug to fail after 2 years/40,000 miles? 

The dead plug in my photo above was reputedly changed just before I bought the car in 2011. It failed in 2017, but the mileage was only about 40,000. So it is quite possible. It looks to me like it had not sealed properly, there is carbon & gunk above the seal point. Also the end is bulging out a bit, it was a bit of a job to remove it. The other one in the photos was the same vintage, next cylinder, but it was in fine condition.

You can easily see the difference in one photo where they are side by side.

[Albert27]

So I've been out today messing about trying to get at the glow plugs.

I got to the 1st and 2nd ones but i found it very difficult to get a steady reading.  It would jump from 0.00 up to 1.7 then rapidly decrease back to 0.00.  When i had no connection or circuit the default screen was just (1.).  I would find a circuit and then it would read 1.7 or less then back down to 0.00.  Is that normal or is that just a poor connection on my part?

In terms of the other two glow plugs, I know Tom said about loosening the EGR cooler but there's also a black piece of plastic that the glow plug wires clip into.  It's in the way, how/did you remove it?

[TomsFocus]

I reckon that plastic bracket is just bolted on underneath, likely to be 10/8mm bolts done by feel.  I can't actually remember doing anything with it though. 

Resistance shouldn't jump about like that.  I reckon you were shorting the meter to get the 0 reading.  Touching the earth of the plug (possibly without even noticing with the lack of space) rather than the live side.

Edit - If you have a quick look at this video, there's a visible bolt head at about 1 minute (vid starts at 55s), I think that's the plastic bracket you mean?  Though it appears to have a cut-out for the plugs as well.

 

[Albert27]

Hard to tell but yes I think that is the one.  I felt the bolts but the one seemed attached to a bracket on the egr cooler too.  

I had the positive 'prong' right on the tip (the bit that goes in the electrical cap).  I put the negative around the side of the glow plug further down.  Too far down got no reading.  Where would be another good earth apart from the plug itself?  I tried the engine bloc but no circuit, even tried the body work by the wiper arms.  What do you mean by the live side?

Cheers Tom

[TomsFocus]

Just have to keep feeling around for the fixings or try to work around that bracket I guess.  Everything comes off one way or another lol!

The visible live side of the glow plug is literally just the tip.  The main body and nut are the earth side, in contact with the block.  It sounds like you were in the right place so I'm not sure what happened there.  It may have been easier to remove them rather than test in situ.

[Albert27]

2 hours ago, TomsFocus said:

Just have to keep feeling around for the fixings or try to work around that bracket I guess.  Everything comes off one way or another lol!

The visible live side of the glow plug is literally just the tip.  The main body and nut are the earth side, in contact with the block.  It sounds like you were in the right place so I'm not sure what happened there.  It may have been easier to remove them rather than test in situ.

Ok cheers mate. I think I will have to remove them - it just looks like such a fiddle to try and get a reading with them in!  Although I'll probably get equally frustrated trying to get them out!  Will use a bit of plus gas on them before i try.

[Tdci-Peter]

10 hours ago, Albert27 said:

I would find a circuit and then it would read 1.7 or less then back down to 0.00.  Is that normal or is that just a poor connection on my part?

It is extremely difficult to make really good contact when just using probes or prongs on the meter. Strong croc clips usually make a much better connection. You have to break through the oxide layer that covers all metals (except gold and a few similar noble ones), and that takes quite a lot of pressure. Cleaning with a file or sandpaper helps, but a thin oxide layer re-forms instantly.

Measurements below a few ohms really do need very good contact, or you are just measuring your contact resistance.

But if you are reading 0 ohms to 2 ohms using just the prongs held by hand, that suggests to me the tested plugs are quite likely to be ok. A full test needs removal, and either accurate measurement with 2 meters (one for current, one for volts), or just putting 12v on like I did to heat it up. Though preferably without setting fire to things, or burning yourself!