XANTIA HDi RUNNING ROUGH

[Skull]

HDi doesn't have a timed fuel pump ....

[Huskyxantia]

1. The Light Blue Smoke (At Startup)
​Blue smoke is burning engine oil. Right after a total rebuild, this is actually incredibly common and often completely harmless for the first few heat cycles.
​Assembly Lube and Oil: When building an engine, a lot of oil and assembly paste is used on the pistons, rings, valve stems, and bearings. This initial coat burns off within the first few minutes of running, creating a light blue haze.
​Piston Rings Seating: New piston rings need time to "bed in" or seat against the freshly honed cylinder walls. Until they do, a tiny amount of oil can bypass the rings into the combustion chamber.
​The Verdict: If the blue smoke clears up after a few minutes of running and doesn't come back until the next stone-cold start, it's highly likely just assembly oil clearing or rings finding their seat.

[Huskyxantia]

​2. The Transition to White Smoke (When Warm)
​White smoke is usually one of two things: unburnt diesel fuel (atomized but not ignited) or coolant. Because it happens after the engine warms up, pay close attention to how it smells.
​Scenario A: It smells like sweet chemical/acrid vapor (Coolant)
​If it's thick, sweet-smelling, and lingers in the air like a cloud, it is coolant getting into the cylinders.
​The Cause: A torque issue on the cylinder head bolts, a slightly misaligned head gasket during assembly, or an issue with the cylinder head sealing surface. As the engine metal warms up and expands, a tiny gap can open up, letting coolant weep into the combustion chamber.
​Scenario B: It smells like raw, pungent lawnmower exhaust (Unburnt Diesel)
​If it has a sharp, eye-stinging smell of raw fuel, it's a fueling/timing issue.
​The Cause:
​Injector Coding / Calibration: The HDi common rail system is highly sensitive. If the injectors were mixed up, weren't coded back to the ECU correctly, or have slight internal leakage at operating temperature, they will over-fuel or spray a poor pattern.
​Fuel Timing or Glow Plugs: While glow plugs mostly matter for start-up, a faulty coolant temperature sensor can fool the ECU into injecting the wrong amount of fuel as the engine warms up, leading to incomplete combustion.

[Huskyxantia]

What to do next
Check the Exhaust Fluid Smells
Immediate
Safely smell the white smoke. If it is sweet, stop the engine immediately to prevent hydro-locking. If it smells strongly of raw diesel fuel, it's a fueling issue.
2
Monitor Liquid Levels Closely
Over the next 2-3 heat cycles
Keep a strict eye on your coolant expansion tank and your oil dipstick. Check if the coolant level is dropping, or if the oil is turning milky/frothy (signs of cross-contamination).
3
Check Injection Parameters via Diagbox/Lexia
Diagnostic Scan
Plug in a Citroën-specific diagnostic scanner. Look at the injector correction values when the engine transitions to white smoke. A high correction value on one cylinder points directly to a faulty or uncalibrated injector.
4
Give it a Gentle
If fluids are stable
If the smoke smells like fuel/oil rather than coolant, and levels aren't dropping, the piston rings might just need a proper load to seat. Avoid idling it on the driveway for hours; take it for a gentle drive varying the RPMs to help the rings seal.

[Huskyxantia]

And , the one we all dread ... head gasket possibly failed..which there is pressure tests to rule that out as you may already know , id say that would be the first step .

[Huskyxantia]

Im going to lay down in a dark room now to rest my brain. I really hope you do get an answer.

[Skull]

Thanks for those comprehensive posts HuskyXantia

I'm not sure if I have any enthusiasm left though ....

[moizeau]

Beer o'clock then

[Huskyxantia]

. And why not crack open a cold one and let the days results fade away .

[CitroJim]

Hi Gary, only just seen this Good advice so far... I have nothing useful to add except to strongly recommend a leakdown test...

Keep is posted...

[Stickyfinger]

My instinct on that smoke (the way it "floats") is a fuel/combustion problem....not seen it, not smelt it so only a hunch

[Skull]

Well today has confirmed:
What started out as a Core Plug corroding/leaking
Led to a rough running engine on re-start
Led to a smoking engine
Led to fuel injection mis-diagnosis (No.4 running)
Led to Jim and Mick visiting (Mick won diagnosis)(No.4 not running anymore)
Led to a broken Inlet Camshaft Follower
Led to a Cylinder Head rebuild
Led to another Cylinder Head Gasket
Led to a nice sounding engine but still a bit smokey
Led me to believe all was well so I done ABS rings
Led to a few laps of the block where it was smoking
Led to another Compression Check 21/21/24/24
Led to Turbo pipe’s inspection
Led to fresh oil being found in the lower pipes
(They weren’t that bad after 168k but I pulled a rag through them so I know they weren’t oily before the long lay-up)

So it would appear either early on or due to being laid up the Turbo Oil Seals have dried up

I’m going to offer it here as spares or repairs but you’ll need a trailer for recovery because as soon as it gets to the turbo zone it smokes badly.

Runs and drives currently…I’ll do a listing here and then on eBay before it heads for a scrap yard

[mickthemaverick]

I fully understand your frustration and general despair Gary but having come so far might not one more job warrant it rather than waste all you've done up till now? https://www.ebay.co.uk/itm/267690949148

[Huskyxantia]

Its worth it for that price .

[Skull]

Sorry but I have no more desire to fix it ....

Be my guest .... viewtopic.php?t=89622