E30 Zone

I have recently had my clutch and flywheel replaced (finally that judder is gone! ). Since the repair my E30 started to misfire in heavy rain. It only happens when I drive through heavy spray (for example driving behind a truck).

When it happens, there is no power and the rev counter drops and jumps back to the right position. It never happens at idle/low revs, only at load (I think starting from about 1500rpm, maybe 2000).

The garage has checked some connectors and rotor/distributor. They didn't find any suspected causes. My leads are new (OE), rotor and distributor about 1 year old (OE).

My garage says it might be the coil, but does this really get wet? (I think it nust be something that catches water)

My suspect is the crank sensor, does water have any influence on it? (when it's dry, engine runs silky smooth). Do you guys have any other suggestions?

if it's dropping the rev counter, i believe that rules out it being the HT circuit (leads, plugs, rotor, cap). the rev counter is fed from the low tension circuit so even if you've got a few leads disconnected, it will still run the rev counter. i'd be suprised if you could get much water near the coil as it's up high and near the exhuast so will keep warm and dry.

you could well be on the money with the CPS though, they often get damage on the wire that runs up to the loom. rubbing the crank pulley, chafing on an edge if badly routed etc. this is much likely to get wet and cause problems due to it's location.

unplug it from the side of the inector wiring trunking (been a while since i've had a M20 but i think that's where it lives), feed it through and check for damage.

I'd lay money on the injector loom plug below the inlet?

ahaa, that too! I always forget that as i've been lucky enough not to have a problem with it yet

i would say that too as i moved mine out the way when changing the gearbox, (undoing bolts to the starter)