Took It For A Run... Here's the results.
To start with when cold it continued to mis-fire. I took it out. First thing's first, the brake pedal has a fair bit of travel. At first I considered parking back up, but the brakes did work... Eventually. The test drive continued, lots of engine braking. Lots of distance between me and the car in front. Maybe if everyone drove around with utterly s..t brakes there would be less crashes on account of the amount of space you leave!
As the drive went on the engine seemed happier. The tappet noise seemed to be, at least out on the road a bit more settled. It did however seem a touch lumpy.... Took it out on the dual carriage way, got up to speed. Car seemed fine, apart from the odd lumpiness...
Got within about 500 yards of the house, the oil warning displays followed by a buzzer flashing away! Oh no! But.... if I had lost all that oil, where did it go? I'd expect the back of the car to be caked in it, but it simply wasn't. The absolutely useless oil dipstick showed that oil existed, from what I gather that's as good as you can hope. I stuck 4l in from dry, which I understand is probably plenty for this engine from dry.
My theory is that the oil sensor thing on the bottom of the engine was dry for around 3 weeks, the engine sat oil-less. I reckon that maybe the oil sensor is a bit sticky... If it happens again I'll strip it off and eyeball it.
Worse, when the car was stopped for a minute while I contemplated the future, the thing refused to start back up. It just sat there turning over. Gave it some beans and it spluttered back to life. After that it seemed as it was before, rough idle. So I parked it up and walked away.
The codes read that there was once again a misfire on cyl 1 and something or other to do with the cam adjustment. When it eventually got started again the camshaft code had vanished and that cyl 1 misfire was left, starting at me! These all appear as "pending codes", not sure what that implies, maybe they need to be an error for a length of time or between runs before they become "stored codes"?
Oh, and the EML didn't come on at all. Despite the slight roughness.
So my thoughts now are.........
- Bleed the brakes. Get that sorted as a priority before I get back in for a drive. I used an easy bleed, but it looks like the tyre pressure has been a tad lower than it really needed to be to bleed properly. Also I hate bleeding VAG cars after they have gone dry, every mechanic I speak to also says it's a pig to get them right. My old 80 Cabrio was the same. My S8 was the same, now this A2 is the same, they just seem a total pig to bleed.
- Fuel filter. I haven't replaced this yet. I need to do that. I also reckon the car sat for a good while, when I got it there was a touch of mould growing inside. So it's a safe bet the fuel is old and probably not up to scratch. Maybe the cause of the misfire? I doubt it. Possibly the cause of the poor hot start? Either way, it wants doing.
- I have bought a Forte fluid that is essentially "shut up tappets". Well that's what I'm calling it. Know some mechanics that swear by it.
My working theory on the engine problems is that the car has sat for a while, my understanding is that these engines tend to struggle with condensation build up, which is hardly a surprise with all the oil filler nonsense going on. I think that the top end has probably a film of corrosion from sitting around either in my garage, or out in the elements for many months (with poor fitting oil caps) and it's just full of sticky components. I hope that the oil additive and a good few runs on motorways free it all up and make it wonderful.
There was about 10 minutes of driving where it was actually a pleasant wee car, when stopped at lights the idle seemed far steadier, it accelerated without grief, the suspension work seems to have been good, no clunks rattles or bangs and it went over bumps nicely, I was very happy with it.... For a while!
The only reason I'm happy to stick with it is - there's no smoke, there's no milky oil, there's none of the worst red flags. I still believe it's a good motor fundamentally...