Deafening bang on startup

[Red Morris]

My car has been sat for 10 or 11 months dues to a brakes issue. Now it’s (hopefully) sorted I went to start the car today for the first time. I read up on starting sat cars and did some basic steps as 1 year seems to barely count. But nothing prepared me for a deafening bang (explosion?) on startup. I jumped out the car and saw smoke, so I high-tailed it out of the garage. No more smoke appeared, and once the initial ringing in my ear started to go I could hear dogs around where I live barking and people coming out to see what the noise was! My right ear is still ringing 40 minutes later.

Does anyone have ideas as to what this was? The car has a very loud exhaust that will make loud bangs in tunnels. Was it just the mother of all back-fires? Or is something more sinister afoot?

I’ll list my steps here so they aren’t in the narrative.

1 – pulled all the HT leads from the plugs.
2 – let the fuel pump prime and cranked the engine in increasing duration, about 5 times. All sounded like a normal startup without the catch.
3 – reconnected the HT leads
4 – tried to start the engine – big bang
5 – afterwards I tried the ignition stage 1 and 2. Electrics seem to be fine and fuel pump still primes.

The car is a 1997 Lotus Esprit GT3 (2.0L 4 cyl turbo)

Topic

[Charles]

Sounds like the process you used dumped a large amount of raw fuel into the exhaust. When you reattached the HT wires the fuel in the exhaust ignited. Would have been better to remove the plugs and spray in a little light weight oil before cranking. Does the engine run now?

[Red Morris]

That does make sense. I was only thinking about getting oil up into the top of the engine.

I haven’t tried it again. I was a bit shaken and didn’t want to risk causing more damage before I had some idea what had happened.

[Author]

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