Fuel Injection relay

[Steve940estate]

Cars are a pain in the backside sometimes, well most of the time actually !

I don't think you are the first person to suffer with a problem like this but I don't now if anyone has ever got to the bottom of it.

When you are driving is it just the engine that stops of is it a total electrical failure ? I have suggested to others, and possibly you to check the ignition switch.

Apart from that I really don't know other than to check through all the supplies and earths to see if there is a problem. A lot of things get earthed to the body with bolt on terminals to which a few wires are joined. All very well when new but there is one down near the ecu which couild be worth checking.

It won't be much help but I have just spent the day getting filthy welding the battery tray in my 940. I'm not sure if an electrical fault might be slightly more fun or not but the smell of burning hair has gone off a bit now !

Hope you can track your problem down.

[brokenbritain]

Your rev counter will only drop when you lose your spark, faulty injection relay etc will still allow rev counter to work....

[clocks2003]

"Your rev counter will only drop when you lose your spark, faulty injection relay etc will still allow rev counter to work...."

Now I am even more confused - if that is possible! The saga was that the engine cut out, with the rev counter dropping to zero even when the engine was still turning due to being pushed round by the road wheels. All other electrics were still working fine. Switch the ignition off, wait for a minute or so and turn it back on and it will fire normally. HOWEVER the only fault code was 1,4,4, which is not the crank-shaft sensor (as one would expect from these symptoms), but the load signal from the fuel injection system being absent...., but you say this would not make the rev counter drop to zero??
Could it be that this signal being absent switches off the fuel ecu, causing the spark to also be switched off and therefore for the rev counter to zero out?

[clocks2003]

Well, it has been a while now and no more cutting out, so it seems oit was the fuel relay! Thanks everyone....

[wrinkles]

Originally Posted by clocks2003

Hopefully switching the relays will have sorted it, but now I know where to look for the next stage it there has to be a next stage...
Thanks again
Andrew

P.S. - can anyone answer the final question in the OP - "Final question, could this problem also cause the rev counter to drop to zero when the engine cuts out even though it is still connected to the road wheels while I am moving (so the engine is still turning over)?"
Thanks
A

That is the crank sensor on the top of the bell housing playing up.

[clocks2003]

Apparently not Wrinkles! I had assumed that to start with and wasted a lot of time messing about with replacements, replacing the socket in the loom, etc etc, but the whole issue has been cleared up by replacing the fuel relays, and the engine management code was completely clear for the crank-shaft sensor...

It seems a faulty signal from the fuel relay causes the engine management system to switch off completely, which also causes the rev counter signal to be switched off.

Worth noting for future reference?

[wrinkles]

That is deffo worth knowing.

[wrinkles]

It sounds like the crank sensor on top of the bell housing playing up.

[clocks2003]

Hi Wrinkles - check the three posts before your last one! :-)