406 semi ecu XUD9, lumpy/idling issues,advance woes

[Piggy]

Before i go and sack off the semi ecu bosch in favor of a mech bosch pump...

Friends 406. done 225k.

Idles rough as a dog and smokes at idle. Drives fine though. Not always does it do this.

Narrowed randomly down to advance/retard by ecu.

If you disconnect the RPM sensor...it idles perfectly, but knocks heavy because ecu has gone full advance. 

Now...the advance could be masking something. But occ it will start and the rev counter wont work and it will run fine. 
Its not drawing air. All earths and wiring has been removed and checked.

Drives fine either way...other than one way it has mega advance.

For now, knock the pump to full retard and disconnected the rpm sensor.
Means it struggles to start a bit...but it drives and doesnt create a smoke screen in traffic...

Basically:

Anyone have experience of this or an idea of a fix?

Or a cheap mech bosch?

[Seb_Ryan]

Had this on a car in work the other week.. Was the connector on the sensor on no4 injector, cut it out and soldered together. May be worth a try

Sent from my LG-H850 using Tapatalk

[Piggy]

This has it on no2 cylinder.
So you just shorted the two wires together??

[Seb_Ryan]

No, just cut the plugs where they join and joined wires together, if you played with the plug in a certain way it would be ok, nothing obvious wrong though

Sent from my LG-H850 using Tapatalk