More megajolt problems - perhaps ?
Turbo Mini Forums

The car has suddenly developed a problem which I think has to be MJ related, as it runs fine on the distributor.

When warming up and driving fairly gently it runs OK, but as soon as you make it work, and before the boost comes on, it will cut dead, but fire up immediately as you release the throttle. The unburnt fuel then ignites in the exhaust and frightens all the chickens, OAP,s, horses etc.

If it runs fine on distributor then it cant be a fuelling issue, right ?

If the Map sensor was misbehaving and somehow making the ignition massively retarded, could this be the cause ?.

(As the problem seems to be load related it made me think of the only load related input )

Robert has suggested that I have a weak spark, which cannot cope with the higher cylinder pressures and that I may have a low tension fault somewhere.

It may be significant that I cant get a reliable rev counter by taking the impulse from either the EDIS, the MJ or a tee off the PIP line, all of which work erratically. I have therefore temporarily disconnected the RC, with no good effect.

Any ideas before I strip out all the loom and check all my connections,for the second time this month, please ?.

David,this sounds like the problem I had recently,with the erratic rev counter AND misfire.I replaced the EDIS 4 unit (£10 from a scrappy) and it fixed it.

'Where does the engine go?'

Great, I have two spare EDIS units so will try that now.

Now runs without the fault and I have a rev counter !!

First replacement ran as above, second one ran engine OK but no rev counter,and both gave a different feeling to the performance of the engine, either to each other or the original one when it was working OK.(Less power, it felt like)

By comparison with the dizzy, It feels slow, the dizzy gave a big surge of power, but I suppose this is all subjective , but do the EDIS units differ in spec and would the MJ not compensate for this anyway ?.

At least I will get to my club annual rally this weekend.

I'd think it depends on the mapping surely tadge? in theory if the map were written to exactly follow the curve of the dizzy, it should feel exactly the same....

Mr. Prawn, the friendly Crustacean- slowly making steps towards forced induction.

I,m pretty sure thats the case. My MJ map is slightly conservative on the advance, to try and keep this, my third engine in less than two years, in one piece for a little while !.

Its likely that the short blast I had on dizzy was with a lot more advance so felt good, but a bit dangerous maybe ?.
(The dizzy keeps on advancing with boost and revs whilst the MJ MAP sensor pulls the advance back of course, which may be why I thought what I did)
I,m sure to try more advance on the MJ eventually, but not until I have finished the rebuild on one of the spare engines.