My girlfriend's Golf is having a bit of starting trouble. Basically, the starter will spin the engine fairly well, up to about 400 revs or so, which if I recall correctly, is about right for a starter. However, the engine doesn't catch. Give it a welly full of throttle, and it'll fire and then bog down again at around 600rpm, and stall. What it reminds me of most is driving an old MK2 Golf with a bunged up ICV / the idle screw turned too far in.
Keep giving it a bit of throttle (say, 5 or ten seconds held at
1000-1500rpm) and it's fine.I replaced the breather pipe that feeds from the oil seperator into the airbox, so it's possible that the throttle body is gunged up, but I can't see why that would cause cold start issues, but not at any other time.
Other candidates are that the throttle body stepper motor has worked out of alignment, and finally there's the possibility that there's something wrong with the charging system / battery / spark, and there's not enough energy to properly ignite a whiff of air and petrol in a cold engine, or the alternator is pulling the engine revs down, trying to get some charge into a near dead battery. The battery is claiming to be fine, with green showing in the window.
Obviously I'll have a bit more idea tomorrow, when I can take the DMM out and get some readings for the battery voltage. Any other possibilities?