Hey all, thanks for answers!
Your discussion about the temp sensor difference makes perfect sense! If I recall correctly then coolant temp and intake air temp had 1 degree difference.
Diesel quality should be ok, I buy it from reputable source, it is winter diesel rated to -32°C. Also when refueling in different stations it does not make any difference.
Glow plugs have been changed a year ago (battling this issue for second season
) relay is clicking and tested one glow plug for voltage (had to check all 4 I guess) it was ok. Glow plug light and a relay click is very quick tho, something like 3 seconds after turning on ignition. Keeping ignition on for longer or turning it on and off a couple of times before cranking does not make a difference.
Injectors were also on the potential problem list, since its the only car and commuting without it would be a nightmare, I purchased a set of used - tested injectors and replaced them over a weekend. It seemed that car was running a bit smoother, but no changes in cold start.
Car runs fine and starts ok when temps are not freezing. No other issues than cold start. Until -10° it does not crank longer than usual, fires up but sounds like it will throw a rod out for couple of minutes, jiggles like a paint schaker, and puffs out white smoke (would indicate unburned diesel, but not a lot of smoke).
When it was -15°C it cranked a couple of turns longer, but also tried to fire up, made a couple of bangs and then stalled. It starts at third attempt or will keep running on first one if throttle is applied to rise the rpms up. Still sounds like it is going to disintegrate...
I assume some of you will say that compression is possibly down, but wouldnt it cause excessive blow by?
As Zork perfectly said - old diesel engine realm
Egr was blocked for a shot period to test - no difference.
No visible coolant usage.
No significant oil usage.
Air flow at idle ok according to my calculation.
Fuel pressure right after cold start goes to ~40 000 kpa, I assume its ok since it tries to run ar 950 rpm.
Throttle flap not sticking (replaced Y-shaped pipe bit, and also experimented with vacuum hose removed).
Battery is a couple of years old, with a bit more CCA.
Starter also works well.