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Discussion Starter #1
The ECU of my 1.6 petrol has failed with a familiar lack of ignition on 2 cylinders.
1) does anyone know which electronic output device has failed so that I can replace the chip?

2) I've changed the ECU with an identical tested one, same codes, same model and using its own key placed close to the ignition barrel. But engine will not turn although the cluster lights are on. Any ideas why it doesn't work?
 

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Somebody told you the key matched ECU when it doesn't?

The coils fail at 30X the rate the ECU does to do the same thing.

Listen to your own words..........an 'identical tested one' and 'same codes' arguing with each other and screaming to you something, that it's likely not ECU (around here we call it the PCM).
 

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Discussion Starter #3
Somebody told you the key matched ECU when it doesn't?

The coils fail at 30X the rate the ECU does to do the same thing.

Listen to your own words..........an 'identical tested one' and 'same codes' arguing with each other and screaming to you something, that it's likely not ECU (around here we call it the PCM).
I've replaced the coils, and it has already been tested and the fault shown to be in the ignition circuit on 2 plugs, so almost certainly the ECU which is common.
I've tried it with 2 working ECUs with their keys, same result.
The only thing is maybe the new transponder is not near enough to the sensor ring?
Seems only the specialists who repair these boxes have the inside knowledge on which components (output diodes?) need replacing, even though it happens often and they would be very cheap.
 

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The ECUs there must be junk, they simply hardly ever fault on spark here. 99% of the time it's coil only with that fail. I've changed like 6 now on my two cars.

'...it has already been tested and the fault shown to be in the ignition circuit on 2 plugs, so almost certainly the ECU...'

That is no proof at all of that deduction. That fault is very easily the coil, it actually being two in one unit. And if the ECUs are 'working' as claimed and second one instantly did the same then you are hard pressed for it to be them. Unless you have figured out a way to blow out the spark control instantly.

There is no 'output' there, the spark comes back in as input, the ECU grounds them using switching transistors. Your output is simple constant 12 volt to power the coils.

All assumes the use of the standard 4 tower coil.

'The only thing is maybe the new transponder is not near enough to the sensor ring?'

Mine are a good 2 inches away, I do not use a chip in key at all. Both cars run fine.
 

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Discussion Starter #5
As I already said, it's obviously not the coil which has been replaced with new. Mk1 ECUs were known to suffer this fault if you care to check. Of course US ECUs are far better than any others.

"...the spark comes back in as input.." That's an interesting way of putting it! There's no coming back, just the primary coil being switched by the ECU with protection diodes for the back-EMF, and maybe one of these failed as is known.

Turns out that putting the chip within mms of the sensor ring solves the problem with the new ECU, so unlike your case its position is clearly very critical.
 

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Uh, you absolutely CANNOT switch primary without it first going back to the ECU to be grounded, that IS an input.

The key chip does not have to be that close, you just haven't found the lesser sensitive area yet. It's not outside the steering column shrouds, you remove them to find it. The RF pickup area varies all around that sensor ring, it can be little to nothing up to the couple inches I found.

If the engine still not hitting on all 4 then check the coil connector, they commonly crack or break wires close to coil and sometimes just up inside the plastic to not be seen. If that Euro model has EGR then the harness sometimes runs close enough to it to melt too and faulting one half the coil sometimes doing it.
 
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