Xantia ECU with bad memory...?

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JamesQB
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Joined: 13 Aug 2003, 18:01
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My Cars: Citroen Xantia 1.8 - I miss this car a lot.
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Xantia ECU with bad memory...?

Post by JamesQB »

Hi,
My Xantia 1.8i '96 petrol car is being a bugger again. A couple of weeks ago, I jumped into the car, started it up and started to drive off, noticing that it was really lumpy and almost kangaroo'ing down the road in 2nd. When I slowed down at a junction, the engine just stalled and when I tried restarting it, it just would not idle, instead dying each time unless I revved up continuously. After eventually managing to get home with constant stalls every time the engine speed dropped, I parked the car and took my foot off the accelerator only to find it was now idling although still not correctly.
A friend advised me to leave it idling a few minutes while tapping the accelerator once in a while, I did this and the car seemed to get better and then drove okay.
Jumped into it yesterday morning to find it had done it again, the ECU seems to 'forget' how to time the engine and it means it won't idle and running is terribly lumpy. Took bloody ages to get it running and idling again, I can't seem to find a proper method to get it to sort itself out, any ideas?
Again, this morning with an appointment to keep, it'd done the same thing! It kept stalling and in the end I had to pull over, rev up all over the place until the engine had done something to allow itself to time the engine closely enough to idle without cutting out and then just leave it while revving at all ranges in the hope that something would work. I was eventually able to drive off with the engine running smoothly.
That's two days in a row and it's now getting annoying, never know when it's going to do it again.
I have no idea what to do and I haven't got the cash to go to the garage to get them to read fault codes or check the ECU out or anything... Can someone help please?? [:(]
Thanks,
James
andycarter
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Post by andycarter »

James,
If you've got no $$, and assuming you've not already done so, first visually inspect everything thats free i.e.
- Vacuum hoses not split or detached
- Electrical connections clean and secure
- No leaks in fuel system
Then start worrying about the ECU.
Andy
Tepi
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Post by Tepi »

I don´t know the correct English word for the part, but direct translation is "stepping motor" and it is located near intake manifold. It should be either cleaned or replaced, cost is about 100-150€ here in Finland for the part.
Just a wild guess... ;)
David Goddard
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Post by David Goddard »

Sounds very much like the £12 (green) engine coolant temperature transmitter. If it is shorted out, the ECU thinks the engine is hot, when it cold.
Hence it won't like starting and run poorly until warmed up - which takes longer than normal as it keeps stalling etc.
wheeler
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Post by wheeler »

if you have an ohmeter you can check the resistance of the green sensor,should be about 2000 ohms at about 25 degrees C & 200-300 ohms when at running temp.if its short or open curcut then you know its faulty.
I think Tepi is talking about the stepper motor,it is another possibility,it may be worth removing & cleaning it and the housing it sits in (but do not move the plunger in or out as this will damage it)as they are very expensive.
NiSk
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Post by NiSk »

The "Axle motor " Tepi is talking about is probably the stepping motor. A well known cause of lots of problems on many diferent Citroëns.
Have you tried disconnecting the battery for 10 mins and then reconnecting it? (after fisrt checking that you have the code number to any stereo you may have fitted)!
This may well clear the ECU's memory problems.
//NiSk
Tepi
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Post by Tepi »

Yes, I think we are now talking the same thing: stepping motor. As far I understand it's way to function, it shouldn't disturb when you are keeping the rpm's off the idle speed (i.e. driving in gear any speed).
Had idle speed problems in my Xantia 2.0 8V -93 when cold, replaced the stepping motor and now everything seems fine.
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