Odd startup behaviour

[bmnelsc]

I've noticed a funny situation with my 1991 S2 when hot or on a restart (my clutch is a bit of an on/off switch when hot ). If I release the key before it has actually fired (if you release the key just as it is firing - it will actually start but it seems like it is ignition before TDC that is starting a power stroke and taking over rather than the starter motor turning the engine into the power stroke - if that makes sense) then the engine won't run properly - seems to be fuel starved and won't rev. It will idle very roughly and won't seem to "clear its throat". If I let the engine "fire up" before releasing the key - it runs fine.

I haven't tried to reproduce the scenario but the last time it happened (couple of days ago) - I knew the engine wasn't going to run properly as soon as it started - had to switch off and re-start.

Any thoughts?

 

[GlennS]

My S2 also exhibits very occasional start-up oddities. It will sometimes start and remain resolutely "lumpy" unless I switch it off and then back on again. I hadn't associated it with not turning the key for long enough when hot-starting but I will keep an eye on it from now on and see if the cause is the same.

 

[simdel1]

Very strange! My initial thought is cam sensor. It sounds almost as if unless the engine has a good few clean rotations on the starter whilst it's firing, the ecu is unable to figure out where tdc is. I'd try some contact cleaner on the cam sensor connector first to see if that makes any difference.