Engine bang on startup

[fla]

Went to start the car today turned the key and it made a kind of loud bang like a major electric short. It then turned over but refused to fire for a few cranks. Then finally fired up and settled to a smooth idle. Haven't checked fuses yet but any suggestions? Wiring around the battery looked ok as did the main engine looms. I could smell something smoky but there were no obvious telltale signs
A bit disconcerting i can tell you!

[easypops]

Could be the isv damper, they go off with a bang, as does the belt tensioner when the bearings give up, although I’m fairly sure you’d know if it was that

[fla]

Thanks Easy.
I've converted mine to obd2 so have the motorised throttle body and no isv damper.

[Jim Bowen]

I've had things like this in the past, like a back fire that seems to come out the air filter.

[fla]

Ok thanks Jim. Was it accompanied by any smells? Just trying to understand what exactly happened. I'll remove the BMC and see if there are any indications. Its perhaps nothing to worry about but more just to make sure it doesnt happen again

[Jim Bowen]

Nah, no smells, that is a little worrying

Is the alternator wiring ok? I'd also check starter motor too, see if anything shorted out, might be signs of something burnt.

[fla]

Checked the alt and starter motor wiring. All looked ok. Car made a bang again on startup but sounded like it came from the fusebox area so i suspect there might me a short somewhere there.. strangely though it ran perfectly for the next 20 miles back home. Schrick performed nicely when needed too
I'll check the fuseboard and connectors to it as well and perhaps see if there are any stray screws causing a short on the wiring.
Incidentally how hot should the relays get?