Engine ECU compatibility

[BrendanM]

I have been experiencing consistent cold starting issues (and other issues) but I have made some progress today.

When I replaced the Bosch engine ECU in my 1996 2.0i petrol turbo XM with one from my scrapped car it started as it should.

The scrapped car is a 1997 XM with the same engine type (XU10J2TE) but has cruise control and aircon.

How do I find out if I can use the healthy ECU permanently?

[xmexclusive]

Hi Brendan

Just see how it goes.
The cruise is a mechanical system on petrol XM's so will have no ECU input.
On aircon the new ECU will sometimes try switching out a relay that is not present.
Neither of these are likely to be a problem with car running.

John

[BrendanM]

I was also wondering if I had anything to lose by opening up the faulty ECU and trying to faultfind the problem.

I have qualifications in electronics and 'hobbyist' experience.

If the faulty ECU has little economic value then I might as well have a go.

Are there companies that repair ECUs or do they just reprogram them?

[BrendanM]

I fitted the borrowed engine ECU onto the metal plate and slid it into position.

I then took the XM for a test drive. It started quickly and No problems were found.

I've been thinking about getting the Lexia diagnostic kit to see if there are any clues to the lack of acceleration which is still there.

I don't have any laptops and I have not used Microsoft Windows for years.

I am a skinflint Ubuntu Linux user.

A big thanks to xmexclusive for his help.

[xmexclusive]

Hi Brendan

If you open up, look for dry solder joints, cracked copper tracks and dried out electrolytic capacitors.
It might be worth just cleaning up the main connector contacts first, the try that ECU again.
This original ECU was having trouble seeing all the engine rotation pulses.
You proved the sensor was not at fault.
That suggests a poor contact somewhere.
ECU specialists charge well for their services so few XM owners go that way.
My comments on the cruise system were a bit brief.
The vacuum cruise system fitted to most XM's is mainly mechanical.
It does have some electrical components and its own dedicated cruise ECU.
This will be found bolted to the outside front of the main ECU box.
It has no electronic communication with the engine ECU.
That was the point I was trying to make.
For lack of acceleration it may be worth looking at the throttle position sensor and its wiring contacts.

John