Started noticing that my tacho fluctuates when driving at a steady speed. The clutch is not slipping. I seem to remember these are supplied by fueling pusles. If I'm correct would this indicate I have a fuelling problem?
Looking forward to any replies. THANKS.

The top dead centre sensor does indeed power the rev counter, in fact if yours has mechanical fuel injection, thats all it powers! It is located at the top of the gearbox bell housing immediatly below the cylinder head under the turbo air pipe. Its not very easy to get at without a bit of dismantling, but hopefully you won't need to. The problem is more likely to be the two pin connecter just above it, mounted on a bracket to the end of the cylinder head, its a square arrangememnt and the wire that comes from the sensor is the one that is fixed to the bracket, the lead to the loom unplugs. Pull it apart and give the pins a good clean and smear a little grease on them. If this doesn't do the trick, if you have access to a multimeter, measure the resistance across the connections to the sensor, if my memory serves me correctly (and it doesn't very often) it should read about 20 ohms, if it does, and the plug contacts are clean, you could have a poor connection on the instrument panel connector. Having said that, mine read OK but the sensor was actually faulty, it had been damaged, but the symptoms with that were, reading up to 1000 rpm and the dropping back to zero. I hope its the easy option!

Peter.N.

The problem is sitting in the left of the engine - EGR ECU It's in the plastic box surrounded by other ECUs (Hydroactive, ABS). My solution (a replacement one) was taken from the scrappies for 20eur

The fault in the EGR module (if this is the problem) can easily be fixed by adding one resistor to the main board inside the EGR module. Unfortunately I do not recall the originator off this picture.

Kind regards
Jens

I don´t know where the atached picture (47 kb) went so I´ll try once more. If the picture is still missing please mail me and I will mail it back.

Kind regards
Jens

Can I ask for some clarification guys?

Is this the 2.1TD engine( code XUD11ATE/P8B or XUD11BTE/P8C)? Whats the RP number?

The P8B has a purely mechanical injection pump and has no engine ecu.
The P8C engine is controlled by a Lucas DCUP2 ecu.

In the case of the P8B the tacho brains is in the dash and the two wires from the TDC sensor go straight to the dash via 3 sets of connector plugs (no ecu).

In the case of the P8C the tacho is driven by the Lucas ecu which by coincidence also does the EGR.

I can't quite see the connection between the tacho problem and the EGR ecu. I can't find an ecu which only does the EGR and nothing else. Can someone confirm this is definitely the case?

Cheers

noz

This is country specific. In Denmark a P8A engine with Bosh mechanical injection will have an EGR system. The EGR box looks like an ECU, but the only thing it does is to control the EGR valve, which is powered by a small vacuum pump under the right wing. To do this, it uses the taco signal, the throttle position and the engine temperature. This is the reason why the taco is connected to via the EGR unit. On cars without the EGR unit, the taco signal is converted in the tachometer.

/Jens

It's PHZ with electronic EGR control. P8A has no EGR. There is P8B with simple EGR - only using a couple of switches. All of them are XUD11ATE with different suffix - /Y(phz) /L(p8b) or none (p8a)

Hi Sharo,

OK, I've found the wiring diagram now. I can see that the Tacho is fed from the EGR ecu.

I just wonder if this helped stjxs01 with his tacho problem?


Cheers

noz

Just thought I would mention that mobile phones will and do cause the rev counter on XMs to behave strangely, this has happened on both my XMs. If the phone is within about 12 inches of the rev counter the needle will flick around the gauge as the phone 'registers'. Took a little while for me to realise this was the cause!