1997 Xantia 2.1td Surging And Racing

[foxman]

The car is an estate that uses the Lucas EPIC system (drive by wire)

Going down the motorway the car suddenly sped up slowed as if I was moving the accelerator then took off like crazy to 90+ before the yellow engine management light came on and the car slowed to a chug. I pulled over and the engine was running lumpy. I turned off, restarted and it was fine so I carried on. After 30 miles it started again and I just trundled with yellow light on for the rest of my journey. The car ticked over at a fast rate with a rise and fall of engine revs.

Since then the fault came and went for a few weeks it would sometimes start to show with a slow reaction to taking the foot off the accelerator pedal when changing gear before starting to surge a little on it’s own.

 

At first I thought it was air in the fuel or contaminated fuel then I thought it might be the throttle position sensor. I managed to drive for a while, but it started to take on some more dangerous characteristics, sometimes just surging away without warning. Generally the first clue is a rise and fall on tick-over often followed by a burst of acceleration which then causes the engine management light to come on and then put the system into limp mode.

 

Things have moved on and I have spent a lot of money but still have the problem. I took the car to a Citroen dealer in Rugby and it was diagnosed as having a faulty injector pump and a faulty injector. Not good news, so I found a Lucas injector pump specialist in Leicester, they connected their computer and it sent out fault codes for rotor sensor and other things. They took off the pump and tested it on their test bench but found it was fine. They replaced the faulty injector and tested the car- it ran well until I went to collect it and the same fault continued. They changed the filter, the pressure return sensor on the pump and even sent it to an auto electrician.

No progress and I am now many, many pounds lighter in the wallet. The car will not run normally at all at the moment- sometimes it starts in limp mode, other times it does the rise and fall tickover thing at about 1,400 rpm . I've cleaned various sensor connections and visually checked those I can see.

 

I am thinking of having the ECU looked at next- any other ideas?

[Ronin]

You've pretty much covered all the bases foxman....

It sounds more electrical than a pump/ injection fuelling problem. You shouldn't really get a surge from faulty fuel side issues just a lack of fuel delivery so it sounds like an ECU fault (it cant regulate itself to the correct mapping on the info it gets from the sensors) Thus the surge on over compensation.

 

This seems to be similar to a problem that a friend of mine had on a Rover 420 sdi turbo.

We checked everything, it went to the main dealer, auto electrician, fueling rail specialist and not one of them could pinpoint the problem. (they came up with wierd and unrelated fault codes but nothing to stop the actual fault)

 

I happened to come across a crashed Rover (same year and model) in a breakers yard and removed the ECU (£20)..... It worked like a charm and he had no further problems. It did need a visit to the auto electrician to get the mapping codes set properly though as a precaution(1hr labour).

 

Now i'm not saying thats the answer to your problems but it's worth a try. there are plenty of xantia's about now in breakers yards, most with good electrics and engines etc. due to suspension (mot) failures. just make a note of the serial number on the ecu and try to match it up. Just ring around the local breakers yards for simailar age and model types. Your bound to get two or three possibilities. Try and avoid citroen breaking specialists though, they will almost certainly have ECU's on the shelf but don't mind charging the earth for them. Normal breakers have little idea of the value of them or often what the box actaully is in your hand :rolleyes:

 

Also check the wiring loom for any heat damage (melting or dis-colouration) if it has been too close to a heat source you could be getting a short somewhere on it but I assume that the auto electrician has checked the sensor plugs for correct voltage....But going by expereience, heat causes resistance = voltage drop... Thats something that they often miss when they stop and start the car while working on it but often rears it's ugly head again on a longer road test where the heat has a chance to build up.

One last thing.. check and clean all the earthing points you can find... sounds crazy but it might just help.

 

Other than that, I cant think of anything else to help you out...sorry

 

I sincerely hope this helps m8 and you get the car back on the road with not too much hassle. :blink:

 

let us know how you get on m8 ....its a tricky one