Citroen XM Forum

MTXM wrote:

A replacement ECU might be needed but do ensure any replacement has a known keypad code!

Fortunately for Graeme the car has no keypad Jim!

That's a bit of luck Matthew I must confess I thought all TCTs had keypads.. So Graeme will have the RGY rather than RGX TCT then?

I'm now wondering if the MAP sensor is indeed in the ECU on an RGY as it is on the later RGX engines..

Yes by chance my two XMs and two xantias have been without the keypad. Nice little Storage space instead.

I've checked the vac pipe already and it seems good. I trimmed the ends to reattach with a secure fit as well. I'm not certain what the plastic resonator is though - can that be seen or is it inside the ecu?

Aerodynamica wrote: I'm not certain what the plastic resonator is though - can that be seen or is it inside the ecu?

Normally just outside the ECU itself Graeme but within the ECU containing box. The RGY may not have one...

The RGX ECU has a copper pipe where the vacuum pipe connects and then another short piece of plastic pipe within the ECU so it might well be worth cracking the covers of the ECU itself and looking at the sensor itself.

The RGX ECU has a copper pipe where the vacuum pipe connects

I do not remember this on any of my tct Jim and Graeme's car is quite an early example being a 1992 model. Regards, Matthew T.

The RGX ECU has a copper pipe where the vacuum pipe connects

I do not remember this on any of my tct Jim and Graeme's car is quite an early example being a 1992 model. Regards, Matthew T.

Yes, it's surely the early version. It certainly does have the vac tube to the ECU seen here:


And the connection at the ECU is like this:


I think I'll have the ECU out again to record the serial/ model number of the type to be sure.

I would open the ECU to investigate the MAP sensor if I had a spare ECU to cover my actions or catastrophic mistakes!

My apologies Jim and Graeme and after I made my last post I did then vaguely recall the tube mentioned! Although I have switched over plenty of V6 ecu I am not sure that one had come out before, other than to clean the receptacle. If you let me know the numbers Graeme it is just possible I may have a spare I could send! With regards, Matthew T.

Thanks Matthew, I took out the ECU with the Hydractive one this evening. Here's the serial number on the engine ECU:

Still not certain if it's RGX or RGY engine though. I think it's the earlier of the two (RGX?)

The fitting of these MAP sensors in ECU was a standard feature of BOSCH ECU's in the early to mid 1990's.
The 2.5 TD ECU's had them fitted but no pipe work from 1994 to 1996.
From 1997 onwards the 2.5 ECU just had the pcb tracks but no MAP sensor.
Very odd.
Cannot yet find/reach the opened TCT ECU's in the heap to compare MAP sensor numbers.

John

RGY is the earlier of the two Graeme. Both RGX and RGY used Bosch MP3.2 Injection. The RGX is slightly more powerful. 150 against 141. Not a lot of difference otherwise.

Not sure if the ECUs can be swapped between the two though as the RGX was keypadded and needs the keypad connected and working. The RGX is one of the few where the disconnection of the keypad with the engine running to disable it does not work.

If you have no keypad and wiring then that rules out trying an RGX ECU...

S1.5s were RGX engined but yours I'd expect to be an RGY.