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Help...ECU diagram with in/outputs signals

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My car has been at the dealers for some months now and this is the last hurdle .

the engine was rebuild however it was missing some of the cylinders when put on load.

the dealer has said that this is likely due to the ECU 'circuit drying out', causing the wrong signal to be sent to the respective ignintion coil.

this ECU has been removed and repaired by a local specialised but the dealer is concerned that the problem may return so he is saying that he needs to get hold of a ECU circuit diagram showing the actual signals so that the specialist can trace and verify that all the signals are correct.

for those who know the back ground to me and this car '10 things to do when the engine is out' it's been 11 weeks since the psiton liner went and a number of further problems were diagonised, however this appears to be the last barrier to me getting the car back, so any help would be appreacitated

PS the dealer is attempting to source the info from lotus direct, he's been speaking to Chris Brown at Lotus?, may have worng the name but he didn't seam confident in getting the right diagrams

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Unless something has been lost in translation, this sounds a little bizzare. If the ECU was repaired by a "specialist" the faulty part was replaced. However, the specialist would have required schematic diagram to troubleshoot the circuitry, unles he was just cherry picking parts. BTW Lotus has never, to my knowledge, released schematic diagrams of the ECU, which was built by EFI in Italy.


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ECU drying out sounds unlikely.

Misfire under load on all cylinders is probably timing or fuel related (cam or crank sensor, fuel pump, filter etc).

Misfire under load on a limited number of cylinders is most likely down to ignition (plug, lead, coil pack). Under load / high RPM the ignition circuit has to work harder so this is when faults show up.

Unless the engine is throwing a fault code (warning light on) then the person repairing the car needs to use a good automotive oscilloscope to test the signals (eg PicoScope - shameless plug for my own company BTW). Wiring diagrams for the car are in the service manuals but someone with experience of diagnosis will not need them.

Unless they have already checked everything with a scope and scan tool there is no reason to suspect the ECU.


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Update, the fault was diagnosed as dried out connections within the ECU. This has been repaired.

That said we have been able to source the original diagrams from EFI Italy, these have been passed on to Lotus H/Q as they did not have a copy themselves. Unfortunately, Lotus will not release them to the dealer.

Now looking for a recommendation on a good ECU specialist on an other thread.

thanks for the assit

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