Full disclosure - I have a Metro. I hope it's ok to post about this here, and I'm hoping some A-series experts may be able to help... ?
The car has a running problem during winter. I've owned 2 Metros prior, and currently own two (other one's a Turbo) - none of the other 3 Metros I've had (998, first Turbo, current Turbo) were THIS bad in the cold, so it must be possible to make this one better. This one is my daily.
My car is bog standard apart (engine-wise) and has been maintained to within an inch of its life by me and by previous owners, judging by the extensive history. It's done over 100k miles now. It's had a new clutch and NOS box during my ownership - but it still pulls like a train. It's a lovely car to drive _when it's warm_. I had it rolling roaded a few months back; not for performance but just to make sure it's running properly. The RR made it drive even better when warm. It's now getting 67 BHP, I think; something like that. Basically it's getting really close to whatever it was supposed to get from new. The guy who did the RR also adjusted the float and carb needle - not sure exactly what he did, but took the dashpot off and measured something then adjusted something. As a result, the idle is way smoother - it purrs! He set up the timing, and adjusted the carb to get the best out of it. It runs great but at the MOT it failed with high CO, so I had to knock it down a fraction (and I left it there - and when warm it still runs fine even after I brought it down a touch).
Shortly after the RR and before the MOT, we had a cold snap and it ran like **** again when cold. Problem is that to get to the RR is a short motorway drive so it's fine by the time I get there. Unless I park it up overnight in his yard and get it on the rollers first thing, then he won't be able to see the problem while it's happening.
The poor running always happens during the winter months, when it's really cold. It sometimes happens when it's cold and damp, but cold is the key: it doesn't mind the rain/fog/mist/damp so long as it's not too cold - but if it's cold (regardless how damp or dry the air is) it'll misbehave. Happens every winter without fail.
Symptoms are:
Low power - like it's only running on 3, but seems equally poor across all cylinders (removing any lead makes it worse - there's no specific lead/plug which is the problem). Feels like the spark is generally weak across all plugs?
Misfiring - really poor acceleration, and extremely poor idle.
Black soot in the exhaust. In fact black SMOKE out the exhaust if I'm really gunning it to try and force some power out of it to drive up a slight incline on the way to work.
Starting from cold, it needs choke - but giving it LESS choke doesn't improve things (and giving it MORE choke, up to max, doesn't seem to improve things either).
Happens not only with choke out but for maybe the first 20-25 mins of running (even after dash says it's at normal running temp, and I'm no longer on choke).
Improves slowly - the change from minute to minute isn't noticeable, but it's fine after maybe 20-25 mins of running.
What I've tried, without success:
It's always running E5/super - always has been since E10 was introduced (it's never run E10).
Air filter is cleaned every ~5k miles - normally a Unipart filter (I bought a bulk load of Unipart filter a few years ago)
Oil and filter changed every ~5k miles - normally use Millers pistoneeze classic.
Replaced air cleaner for a NOS one as I thought maybe the warm air diverter wasn't working.
Checked/renewed the duct between hot air stove and air cleaner.
New plugs (currently using NGK BPR6ES). Plug gaps where checked and adjusted by the guy that did the RR.
New Unipart HT leads.
Dizzy cap (always Lucas)
Rotor arm (always Lucas)
Gone through several different ignition amps - Lucas, Unipart, Intermotor - each time using heat transfer paste between amp and dizzy body, but replacing the amp makes no difference.
Even changed the actual dizzy for a same model (NJT10002) from a low mileage donor.
Tried different coils - gold Lucas sport coil, currently running silver Lucas DLB198.
LT connections at coil are cleaned and I'm using dielectric grease to prevent moisture/corrosion.
Dashpot is topped up with Burlen dashpot oil.
Vacuum advance elbows are recent and I've checked that they're supple (not brittle - no cracks).
I thought it might be the fusible links - I unwrapped the loom to find them, but they're still sealed so I don't want to break the seal. I'm assuming that if still sealed, then moisture/oxygen can't have got in.
Since last MOT I've been putting RedEx treatment through with each fuel refill (it's sometimes on offer at Lidl, so I always pick up a few bottles when I see it - each bottle does 1 tank, and I've put through 6 bottles so far, so the fuel system must be about as clean as RedEx can get it).
This is a bog standard 1275 engine, not the MG version. 12HE engine, unleaded from factory. It didn't come with water heated inlet manifold, and I wondered if maybe I should consider getting one set up? But the normal 1275 has a combined inlet and exhaust manifold, so I'd have thought the inlet would be heated by the exhaust? Other than that I'm bang out of ideas.
Anyone got any suggestions?
