Progress?

I took the car for an MOT on Friday, but it failed due to emissions (not a total shock, but still disappointing), and headlight position. Apparently one headlight is a few mm lower than the other, which is No Good, despite passing IVA and the last MOT. Easily fixed with a spacer though. Emissions are more tricky.

Emissions are all good, except for lambda (air/fuel ratio) which was 1.2, i.e. pretty far off (20% too much oxygen present, though I suspect 1.2 was the limit of the analyser they were using and in fact it was even worse than this). In a perfect world the oxygen and fuel would balance in exactly the right ratio and all the oxygen would be used up burning the fuel to produce CO2.

In my world, however, the prime suspect is an exhaust leak upstream of the lambda sensors, which would explain (a) the excess oxygen as the exhaust flow draws in more air and (b) the rubbish fuel economy as the lambdas detect the oxygen and compensate with extra fuel. Presumably the cat is then using the excess oxygen to burn the excess fuel and hence I'm seeing normal HC (unburned fuel) levels at the tailpipe, which will be rapidly destroying the cat.

After looking for an exhaust leak and not finding one, I took the exhaust apart in search of more evidence, and eventually found this where the primaries join the block:

Exhaust gaskets. Note scorch marks at top left.

Which looks like pretty solid evidence of a leak. I've ordered new gaskets (these are off the old 328 engine and are slightly different to the M3 gaskets, which can't help), and booked a retest. They said they'd "make sure it passes" next time, which is nice of them, but I'd quite like to actually fix the problem.

Lack of progress

Not a lot to say this time round: the front suspension is, finally, all back together, tightened, etc and ready to go. Thanks to Ben for coming round to help me bleed the brakes.

Unfortunately the car's due an MOT so no road testing until that's done... and given the weather at the moment, that hasn't happened this weekend. It will have to wait for a dry day. In the mean time, the windscreen is off (it would fail due to the lack of wipers), and the centre mirror and front numberplate are on in readiness for the MOT. Given that I always tend to drive in a helmet anyway, I'm debating leaving the windscreen off. Might see how that one goes.

In the meantime I got on with some garage upgrades: the garage now features 1700 W of lighting, which also contributes significantly to making it warmer, and may help stop me hitting my fingers with a hammer so often.

And the search for decent wheels continues. The main problem seems to be that BMW owners tend to go for big (heavy) wheels - even on race cars, no one uses 15" because they're all running big brake kits. So finding some lightweight 15" wheels is proving difficult. Team Dynamics seem to be about the only option at the moment, which is not very exciting (or especially lightweight). Keeping my eyes open for some Dymags but not holding my breath as these seem kind of rare.