rocker cover earth?

[paultownsend]

im sorry but my cameras broken, so il try explain the best i can

there is a flat plastic covered lead that attatches to a thin plate on the rocker cover, and seems to dissappear to the area of the coil.
what is this for as during my bvh head it has snapped

Paul

[russ-vdub]

its only for protection really, not essential to have on .. dunno what you mean by "bvh head" tho?

[Diamond Hell]

Don't run the car without it - you can get odd earthing across the vehicle and it can pop the ECU.

[paultownsend]

oh sorry, big valve head!

excellent, so i can earth it anywhere really?

[russ-vdub]

earth is an earth at the end of the day.. just make sure you get a dvm and check that it is actually grounding

[Diamond Hell]

earth is an earth at the end of the day

No it's not.  If you don't earth the engine correctly you can get voltage differences across the body which will result in the ECU seeing wierd readings and possibly voltage above what the circuitry is designed to.  Then you get dead ECUs.

Earth it as it came out of the box and it'll work properly.

[russ-vdub]

where are voltages running through the rocker cover?? these are protective earths, thats all

[Diamond Hell]

It's earthing the engine to the shell.

Is it worth taking the risk of frying the ECU?

[russ-vdub]

agreed its not worth risking it but theoretically you can earth it anywhere on the chassis as all earths go to the chassis at the end of the day

[syncrogolf2]

If you have a carburettor engine then this earth is not that important, but with a GTI digifant injection system this connection has an earth cable dedicated to the ECU and running about with this connected is just an accident waiting to happen, usually when starting up and the starter motor is pulling a lot of current & the usual earth cant keep up, then it can & will leave the ECU stone dead and unrepairable!

BTW this is not just a protective earth but actually part of the ECU injection & knock sensor circuit.