Ok so spent a bit more time on the car this evening, doing some more poking about, trial and error etc.
1)
Oil level - I may have to re-name the thread. For some inexplicable reason, the oil level now appears to be back to normal (just under max), whereas last Friday evening, it seemed massively overfilled?! Surely there could not be any massively increased pressure in the crankcase to make the level rise, as I only replaced the PCV valve a month or so ago. Anyway, that can only be a good thing, and it affirms my belief that the oil looks and smells fine. It was a good two hours + since the car was turned off so the oil level must be back to normal now.
2)
Injectors - with the engine cranking, I disconnected the electric plugs to each to see if there was one that wasn't performing properly, and lo-and-behold, the engine grumbled like a mother trucker when they were disconnected individually. So far so good there, then. Also did a leak back test (ignition on but not cranking, leak back pipe off and clamped) and even after 20 seconds there was barely any leakage from the top of all four injectors.
3)
Misfire - looking into this a bit more, I'm not even sure this is a full misfire, if there is such a thing. When stationary, there is no sign of anything amiss when holding the revs at up to 2,000rpm, whereas between 2,000-3,000rpm there is a distinct (but not hugely noticeable) grumble from what sounds more like the exhaust and what sounds like one of the cylinders is missing ever so slightly. But, the effect is nothing like when I disconnected the injector supply above, nowhere near. The fuel pressure sensor has been changed recently too, plus a new wiring harness, so can't (rather shouldn't) be that.
So realising this above, and having had email correspondence from Bob from Diesel Bob UK who has said it doesn't sound like an injector issue to him, and for some reason with the airbag cover off my attention turned to the MAF. This is where I (might) have had a breakthrough.
Going on Nik Rivers' suggestion -
http://www.nikrivers.com/freelander-td4/maf-sensor/ - I unplugged the MAF and ran a mile or two down the road. To my surprise, there was an imperceptible difference, possibly zero, on performance, low rev pick-up and power further up the rev range. So now I am wondering if the MAF is either kaput, on its way out or needs some connector cleaning spray.
BUT - I thought I had read somewhere on here that the MAF is essentially redundant if you have blanked your EGR? I have, so wondered if that was true.
To summarise
- starts fine but on cold start-up, takes a few seconds to clear its throat (5-10 secs maybe) accompanied by a pretty big belch of whitey-blue smoke, which also clears after the same few seconds. After this, runs fine. Possible injector issue, despite my findings above?
- slight 'misfire' or 'grumbling' as mentioned above 2-3k rpm - I am still wondering if this is a slightly dirty injector nozzle or something?
- MAF seems to have no difference when unplugged, though as above not sure if it is redundant when EGR is bypassed? Unsure if faulty MAF will display any of these issues above that I am experiencing
- I THOUGHT that the oil level was rising again last weekend, but now it seems to read between min and max on the dipstick. Fu*k knows what's gone off there, but seems that is no longer an issue.
- Coolant level does go down slowly, but I think this is a small leak somewhere in the coolant system as opposed to head gasket. The car is showing no other symptoms of HFG whatsoever (no oil in coolant and vice versa, no steam out of exhaust, no increased running temps etc, no mayo around expansion tank or oil filler cap)
- General running of the car, other than first few seconds each morning, is spot on. MPG is very good, expect 40+, power is decent especially since EGR was blanked.
Be great if anyone has any thoughts on what might be causing the morning 'cough' and smoke and the slight grumble at 2000rpm. The rest of it I'll keep a close eye on, mainly the oil level to be fully sure.
Sorry for taking up half your evening with this...
Thanks in advance