Elise s1 - intermittent no spark diagnosis help please.

[dern]

Afternoon,

Could anyone help me diagnose why I'm intermittently getting no spark when trying to start please n a 99 Lotus Elise S1 with a 1.8 k-series fitted along with a turbo technics tt190 supercharger kit (hopefully not connected)?

Every now and again when I try and start the car it turns over but won't start. Removing the spark plug shows I have no spark. There is no consistency to when it won't start, the car could be cold or hot and the weather wet or dry.

I can definitely hear the pump priming, I have fuel in the tank and the engine is turning over strongly on the starter motor. There is no difference between the noise made by the starter or the pump when it isn't starting to when it is. When it starts it fires almost immediately. The car has never cut out when running.

Today I drove it to the shop with no issues but it wouldn't start when I came to go home. Car was still hot. The car coughed as if it was going to start when I first turned the key but didn't. It then just span the engine on the starter. Left it for a few minutes and tried again and it still didn't start. Sometimes just leaving it results in it starting. There is no strong smell of fuel by the way. I called the recovery people who hooked it up to their jump start (by this time my battery was flat from me trying to start it) and it fired up immediately.

On a couple of occasions it won't start and then for no apparent reason will just start.

So far I have...

Bypassed the alarm.
Replaced the distributor cap, rotor arm, HT leads and king lead, coil and the crank position sensor.
Cleaned all the earthing points and battery terminals.
Cleaned all the multiplugs everywhere with contact cleaner.

It seems to me that this must be an electrical issue and while I am confident with diagnosis and handy with a multimeter I'm not sure where to start.

The ecu is standard elise fodder and it has an extra racelogic box to change the timing for the supercharger.

Can anyone help me with diagnosing this issue please?

Many thanks,

Mark

[Egg Chaser]

Camshaft position sensor ?
Knock sensor ?

[sparkybean]

First suggestion i would give is to check for duff wiring. Corroded connectors, shorting wire ect. Go over the loom with a fine tooth comb.

[skid-mark]

has the car got coded keys i had a problem like this on one of my mazdas and it was down to the computer that recives the signal from the key, it was just a little control unit bolted up under the dash but had to get the keys reprogrammed.

[annodomini2]

Duff relay would be my guess, check the coil supply with a multimeter.

[dern]

Thanks for the advice. No coded key, no camshaft position sensor, no knock sensor so I can rule those out. Did a lot of work on it today and believe I've tracked the problem down to a malfunctioning racelogic supplementary ecu which retards the timing for the supercharger.

Cheers,

Mark