[Engine] Smokey cold start and misfiring

[John Bilko]

I did note that even when smoking and lumpy, when the coolant hit exactly 50 degrees the whole thing switched to running perfectly 

Never the less it is still diesel smokey / smelly at start up. I have put some injector cleaner in when filling the tank and we will see how it goes. 

My B9 does not like the cold especially this cold. When it is warmed up it behaves much much better.   It is also smelly - I have had a few diesel motors but none stink like this can do.

I tried a diesel additive but to me it was a waste of time and money. 

In the spring or summer I will take it to Citroen to have it all diagnosed but it is £100/½ hour!!

I have blanked off EGRs in the past but never found it to help that much.

[Sol]

You can't blank the EGR on a B9, it sets the engine warning off so you get a Christmas tree dashboard.

Also I will bet you £200 right now that Citroen won't have a clue what is going on with it. This issue affects every brand of car which uses the PSA HDi 1.6 and no one has ever really gotten to the bottom of why it happens, me included and I spent a lot of diagnostic time and effort on it..I've had 3 HDi engined vans and only one had that issue.

I mapped sensors against each other with live data, nothing ever jumped out. Blanking the EGR (it was an M59 I had back then) made a huge difference, as did disconnecting the MAF as well. Either one worked to a huge extent, so never ended up swapping the MAF but I suspect it or the doser unit was to blame.

[John Bilko]

You can't blank the EGR on a B9, it sets the engine warning off so you get a Christmas tree dashboard.

Also I will bet you £200 right now that Citroen won't have a clue what is going on with it. 

LOL

I do agree.

Mostly,  I will be taking it to the dealer as I will want them to tell me if the clutch needs changing (mine is an "automatic") and when I run it from first starting it while cold it is like I am a learner drive kangarooing all over the place.

Oh no, I sometimes like to blank off the EGR cos I hate cleaning them.

What next with this Citroen...............................oh yes, PX it for something else.

[saskak]

I have a different theory on the cold smoking/misfiring, etc., that I lately developed. I have not yet tested it, but will do so in the short future. I may be wrong in all of this thinking though.

So, the PCV has a spring that pushes the diaphragm, so when the turbo spools up it will close slightly, so the suction does not suck all the oil out of the crankcase. The tension on the spring is factory set for a brand new engine. A brand new engine will have very little blow-by.

With age, the blow-by inevitably increases as does crankcase pressure. So, the amount of blow-by and associated crankcase pressure is highest on cold startup, so this is certain to push against the turbo oil return pipe oil returning to the crankcase. On cold startup some oil will pass the turbo seals due to this pressure until the pressure reduces with reaching operating temperature or lessens with warmer engine parts. So, coming back to the spring. If this spring is stretched out a bit, this will help evacuate the crankcase pressure much easier and likely not push the oil returning from the turbo oil return pipe. My theory is that this might help with the cold startup smoke, smell, etc. I'm not too sure how much to stretch the spring though, probably 1/2mm or thereabouts.

[geoff]

Just buy new - you'll break the cover clips

eg ebay PCV Valve Cover Repair Kit 1.6 HDI 0248L1 circa £10

https://www.ebay.co.uk/sch/i.html?_from=...c=0&_sop=2

[saskak]

Just buy new - you'll break the cover clips

eg ebay  PCV Valve Cover Repair Kit 1.6 HDI 0248L1  circa £10

https://www.ebay.co.uk/sch/i.html?_from=...c=0&_sop=2

Yeah, that's what I did last time I replaced the diaphragm, not that there was any need to replace it though ;-)
Broke all the plastic bits that held the cap on.