Blue smoke on cold start, rough idle.

[Albert27]

Hi Guys,

I'm having an issue with my focus (1.6 tdci '08) which has been going on for the last 9 months or so.  On cold starts I get a huge puff of blue smoke (which has gradually got worse) and the car runs rough at idle for between 10-30 seconds afer and then everything is smooth & drives normally.  I've asked a few mechanics and been told it's a can of worms and it could be a number of things and I could end up throwing hundreds of £'s at it .  What can I do to narrow down the problem or even solve it myself?  The glow plugs were changed 3 years ago and I knew there was an issue then because the car went into 'limp' mode.  I've checked the oil level and it is not obviously going down.  I should add that I've noticed a small drop in mpg.  Averaging 45 where i was getting 49mpg - I know on paper I should get 60mpg but I do a lot of stop start driving around town.

Any help would be appreciated.

[TomsFocus]

Getting an ELM cable and FORScan might help find the issue but it sounds more like a physical/mechanical issue rather than something electrical to me.  Blue smoke isn't always oil either, it can be diesel as well.  Could be leaky turbo seals, leaky injectors, leaky valve seals.  Could even be the DPF choked.  As above, it could be an awkward fault to find and probably not worth it unless something obvious is shown up on the diagnostics.  A quick check you can do is remove the engine cover and look around the injectors for a carbon build up, it should be totally clear, any carbon deposits there shows the injector is leaking.  Might also be worth changing the fuel filter if its not been done recently.

Also they do use oil, or at least mine does and we have the same engine lol, but the excess diesel from DPF regens fills it back up again, so if you top it up before a regen it can end up over-full in my experience, just something to be aware of.

[Albert27]

 

28 minutes ago, TomsFocus said:

Getting an ELM cable and FORScan might help find the issue but it sounds more like a physical/mechanical issue rather than something electrical to me.  Blue smoke isn't always oil either, it can be diesel as well.  Could be leaky turbo seals, leaky injectors, leaky valve seals.  Could even be the DPF choked.  As above, it could be an awkward fault to find and probably not worth it unless something obvious is shown up on the diagnostics.  A quick check you can do is remove the engine cover and look around the injectors for a carbon build up, it should be totally clear, any carbon deposits there shows the injector is leaking.  Might also be worth changing the fuel filter if its not been done recently.

Also they do use oil, or at least mine does and we have the same engine lol, but the excess diesel from DPF regens fills it back up again, so if you top it up before a regen it can end up over-full in my experience, just something to be aware of.

Thanks Tom.

I had the injector seals done two years ago (I assume that's what you mean by leaky injectors and not the injectors themselves...or is it the same thing?). No DPF on mine so that's out.  I'll have a look re carbon build up, but what exactly will that look like?  The fuel filter was replaced 13 months ago (20k miles ago), would it still be worth replacing?  One of the mechanics mentioned the EGR valve could be causing it.....would that be consistent with the symptoms i'm getting?  I've read something though that if you can hear that clicking noise after switching off the EGR is working ok but I don't know if that's right but anyways i definitely hear a clicking noise after turning off.

[TomsFocus]

Non DPF is a good start, as that's what tends to cause more issues. 

There shouldn't be any external leaks or carbon deposits around the injectors as you've had the injector seals done fairly recently, that's another one to cross off the list then, though it can't hurt to check.  The injectors themselves can also leak into the cylinder if they don't shut off properly though, meaning when you start it after being left overnight there's too much fuel in the cylinder, that's not something that you can really check at home though.

The fuel filter is probably due for replacement with 20k miles on it, most on here change them at more like 12k as they often get blocked on these.

The EGR could cause your issues if it's sticking open a bit but I'd expect other issues as well, such as a lack of power pulling away or hesitation in acceleration.  The clicking just means it's getting power really, not that it's fully working and closing completely.

[Albert27]

35 minutes ago, TomsFocus said:

Non DPF is a good start, as that's what tends to cause more issues. 

There shouldn't be any external leaks or carbon deposits around the injectors as you've had the injector seals done fairly recently, that's another one to cross off the list then, though it can't hurt to check.  The injectors themselves can also leak into the cylinder if they don't shut off properly though, meaning when you start it after being left overnight there's too much fuel in the cylinder, that's not something that you can really check at home though.

The fuel filter is probably due for replacement with 20k miles on it, most on here change them at more like 12k as they often get blocked on these.

The EGR could cause your issues if it's sticking open a bit but I'd expect other issues as well, such as a lack of power pulling away or hesitation in acceleration.  The clicking just means it's getting power really, not that it's fully working and closing completely.

Ok great. I will change the fuel filter soon and check the injectors and update the post if any improvement.  Supposing there's none that leaves turbo seals & leaky valve seals.  Are those jobs I could do with my basic experience in cars?  Also would it be worth putting some additive like red x in the tank just in case there is some problem with the EGR or should i just fill up with v power diesel for a bit?

Eurocarparts are saying £40-£50 for a fuel filter - thought it was a bit steep as all the other filters were a lot cheaper (air, pollen etc) but then I haven't a clue!

Thanks again!