how do you earth the ECU - earthing issue

[rushing]

My elan is not earthed . This could be one of the problems that why my elan is misfiring or running badly or A bad earth going in to the ECU . if my ECU is not erthed how do you do this please?.

1. Where do i find the earthing bit on the ECU .?
2. where does the earth go out of the ECU and where in the car ?

i think my faulty ECU might be getting wrong commands and hense causing it to misfire and be lumpy any advise would be nice please. cheers

[rip]

I looked for this on mine with a view to sorting yours:

It branches off from a trunk of cables which run above the ECM. It attaches to the aforementioned trunk about 4-5 inches to the near-side of the ECM. If it is still there, it should have a ring connector on the end which gets clamped by the off-side ECM fixing bolt.

[rushing]

Rip

can we fix this when we are putting the ECU together. i dont know what im looking at.chhers matey

[Candles]

The ECU is also importantly earthed to the base of the coil pack and to the engine block via the intake plenum. If these aren't conducting well then the readings from all the engine sensors will be in error, hence the engine runs badly. I had mine come loose from the plenum (next to the PAS reservoir) where 3 earths come together and the car would hardly run.

[rushing]

has anyone got a pic of where the plenum (next to the PAS reservoir) is so i can have a look if this has come out. I guess when i change the ECu i can have a look at this

[ailwyn]

has anyone got a pic of where the plenum (next to the PAS reservoir) is so i can have a look if this has come out. I guess when i change the ECu i can have a look at this

The plenum is the bit under the bonnet with DOHC embossed in it, the PAS reservoir is the black container to the left of the engine as you look at it from the front, next to the plenum, the ECU is in the passenger footwell. Hope that helps

[Doc Fizzix]

The ECU is also importantly earthed to the base of the coil pack and to the engine block via the intake plenum. If these aren't conducting well then the readings from all the engine sensors will be in error, hence the engine runs badly. I had mine come loose from the plenum (next to the PAS reservoir) where 3 earths come together and the car would hardly run.

I have had this same problem, make sure the coil is earthed. The coil is under the coolant reservoir.

[rip]

I'll check all of those next time I'm over matey.
I seem to remember an earth on your coil packs anyway.

[Doc Fizzix]

I'll check all of those next time I'm over matey.
I seem to remember an earth on your coil packs anyway.

Make sure it is clean! Use a little sandpaper and clean it off.

[rushing]

Change of ECU has made some improvement but not cured the problem 100%. The lumpy effect comes and goes after 35 mins if car running. Car back to the normal faulty effect. Contacted a garage today and they did say that the ECU needs to be earthed for the sensors to work as if not it will try and send different error messages – communication to the engine .Also he said that the conducting would be poor. Exactly what you said candles .

The new fitted ECU is not earthed and I think it might be sending scrambled error codes now and then. . When RIP and I took the old ECU out we could not find any earth wire next the ECU.

I really need to get this earth wire sorted out. I’m still not clear on how to do this. Has anyone got any pictures of there ECU with this on so I’m clearer on what I am looking for? Can I just out a wire under the frame of the ECU and mount it to plenum??? I


Having spent money on the ECU I just don’t want it been faulty again because to the simple fact of not been earthed.

[ailwyn]

You need to sit down with the electrical manual and find out where all the earthing points are on the car, there's not a specific earth wire for the ECU it all goes through the harness.

For each earthing point you need to disconnect the wires, clean up all the connections then re-fit. As has been noted previously, there are earths near the coils, I'd suggest using this as the first clean-up point.

[GeoffSmith]

I presume you are happy that the CAS to coil pack connections (WR11X and W11Y) are good.

The ECU is earthed to the inlet manifold via connectors A12, D1, D6 and B4 and four black cables (see Wiki). The CAS shows one and the coil pack shows two connections to the inlet manifold. It is important that these are all good, low impedance connections. You could connect a jump lead (for example) to the inlet manifold earth and try the other end on the CAS and coil pack earths to see if you can cure the problem.

[Doc Fizzix]

Also, make sure the motor has its earthing straps attached and that they are clean and making good conduct. I have seen people do work on cars and not re-attach the straps and/or attach them incorrectly, this will cause problems if the motor is not properly earthed.

[ailwyn]

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