UK RHD M2.7 348 Running like a B***h at low revs

No doubt,

Thats what I thought, so without the engine running I should have got the speed sensor error from 'both' ECU's. It definitely wasn't presenting itself on the 1-4 bank ECU milk. But, if there is a prob I can't understand why I don't get a CEL from 1-4 bank ECU all this time whilst driving around with the rough running.

 

Been under, both sensors look fine, wiring and connectors are undamaged (look like new actually). The pins are clean and shiny, no signs of corrosion. The gaps are at the top end of the tolerance or just nudging above, one at 0.9 and one at about 0.93. I took the two very thin shims off the 1-4 sensor, bringing it back into tolerance now at 0.8 or thereabouts.

I checked their output once again with an oscilloscope (direct by backprobing the connectors this time). Both outputs are of the correct waveform, but one has lower amplitude than the workshop Fig. The 1-4 sensor has peak to peak of 25V (for the revs part of the signal), whereas the 5-8 sensor is only outputting peak to peak amplitude of 18V.

Do any of you guys feel that voltage shortfall is significant, or do I continue looking for the fault elsewhere?

May just buy a new sensor for the 5-8 position as the cars in the air and they are only a few pounds/dollars.

Suns shining like billho over here in UK (for a change!!!!!) so I'm getting really cheesed off at not being able to drive the mello yello mother.

 

Is 18 volts peak to peak on a Bosch Motronic 2.7 feeding crank rpm sensor significant compared to spec 25 volts?

 

I pulled my plugs (again) and this time noticed that two of them were sat in a slight well of oil in the plug holes. The oil can only have come from between the camcover to head joint, even though when I last had the engine out to do the cambelts/tensioners etc I used new gaskets. I have a suspicion it was the new stainless dome head nuts I used for the camcovers, they aren't quite as deep as the Ferrari ones, so they don't pull the camcovers down sufficiently.

Anyway, I made up something I can only describe as an oversized cotton bud tool, cleaned/soaked up the oil from the two affected plug wells and bingo, the car now runs beautifully.

Now we just need to get yours right. I think you are on the right lines by checking the plugs.