Loud Knocking Xantia 1.9td Lexia fault update - SUCCESS

shaunlfc1 · Post by **shaunlfc1** » 03 Aug 2010, 20:20

Today I learnt that the coolant temperature sensor could be causing my problem, I've tried disconnected it but it didnt do anything.

Continuity is fine back to the ECU and I am getting 5v at the connector end.

But I take it to really see if its not working is too just replace it?

A friend at work has a full diagnostics system on his laptop so hopefully sometime this week I will get to the bottom of this!!

Cheers all again for your help,

Shaun......

MikeT · Post by **MikeT** » 03 Aug 2010, 20:38

The green sensor? You can put a multimeter across the terminals, set to 200K ohms, then run the engine up and watch the value progressively change (I think it's inverse to temperature).

My ECT sensor was faulty but on testing behaved itself just fine up to 60/70 odd degrees then it went haywire. £15 or less from main dealer, and all's well again.

Interestingly, the result of faulty coolant temperature readings meant the timing was being retarded unnecessarily. The differences weren't obvious when driving but the Lexia showed me exactly what was going wrong.

Post by **CitroJim** » 03 Aug 2010, 21:07

Mike, can you give Shaun a ballpark resistance for the Sensor, say at around ambient?

Shaun, I make an assumption you're in Sussex. Perhaps Malcolm (Citronut) might be happy to hook his Lexia up to your car? I guess you're not too far away from him?

shaunlfc1 · Post by **shaunlfc1** » 03 Aug 2010, 21:17

Indeed near worthing, west Sussex.

MikeT · Post by **MikeT** » 04 Aug 2010, 10:04

CitroJim wrote:Mike, can you give Shaun a ballpark resistance for the Sensor, say at around ambient?

I'm afraid I didn't take notes and you know what my memory is like. But if it's like my failed sensor, that won't help because it gave normal readings from cold. Only when hot did it go crazy.

This is my thread on that issue.

http://www.frenchcarforum.co.uk/forum/v ... highlight=

shaunlfc1 · Post by **shaunlfc1** » 04 Aug 2010, 13:35

Could mine be purely set to cold causing the ECU to just set the timing to advance?

What else would effect timing management, the car now has a new crank, injector sensor, I know the cold start solenoid thingy works, all wiring checks out using a continuity test. My colleague is hooking it up tomorrow to his diagnostics so all will be explained no doubt.

MikeT · Post by **MikeT** » 04 Aug 2010, 15:56

shaunlfc1 wrote:My colleague is hooking it up tomorrow to his diagnostics so all will be explained no doubt.

Unless he's got Lexia, I wouldn't bank on it.

shaunlfc1 · Post by **shaunlfc1** » 05 Aug 2010, 20:24

Would the load lever sensor be giving me the troubles I am experiencing, I've tried everything else, diagnostics been delayed til the weekend.

Cheers,

Shaun

Post by **CitroJim** » 05 Aug 2010, 21:50

shaunlfc1 wrote:Would the load lever sensor be giving me the troubles I am experiencing, I've tried everything else, diagnostics been delayed til the weekend.

Cheers,

Shaun

I don't think so Shaun, this pot (and it is just a normal three wire potentiometer) helps the ECU measure the lad the engine is under by comparing throttle angle with engine speed. If the load is high, signified by the throttle being wide open but engine revs are low it will do a timing trim.

Worth a check of course and it can be checked with an ohmmeter or by substitution, Just take care to ensure the relative alignment of pot to spindle is maintained.

I'm not able right now but tomorrow (remind me if I forget( I can run an ohmmeter across one I have here and give some ballpark readings and a test plan for it.

Maybe if the thing is completely open circuit it might make a difference. Also check that it's operating fork is not broken. It's made of brittle plastic and transmits spindle rotation to the pot. It's a tad fragile and gets more brittle over time.

shaunlfc1 · Post by **shaunlfc1** » 03 Sep 2010, 18:06

Hi everyone,

Its been a while, and I've finally had the Xantia linked upto a Lexia.

The resulting fault and the only fault the Lexia showed was "Adjustment of Motion"

My money's on a problem with the timing? Is it possible the timing belt has jumped a tooth and not caused any major problems, apart from causing the horrible banging noise?

Finally a big thank you to Tony (cachaciero) for giving up some of his time to help me out this afternoon.

I look forward to seeing people's opinion on the fault I have.

Thanks,

Shaun

Post by **Peter.N.** » 03 Sep 2010, 18:27

The noise you describe would certainly suggest over advanced timing, if the belt slips it would normally retard it, where abouts are you, do you have anyone near that can listen to it? Or post a video on YouTube.

Peter

shaunlfc1 · Post by **shaunlfc1** » 03 Sep 2010, 18:46

I am located near Worthing in west sussex on the South Coast.

I will try and post a video on youtube tomorrow.

Thanks,

Shaun

Post by **CitroJim** » 03 Sep 2010, 19:31

That fault is normally caused by low fuel pressure in the pump, often as a result of a plugged fuel filter...

If not that then check the strainer in the fuel tank. It's well known for getting very badly choked up and restricting fuel flow very badly.

Here's one:

shaunlfc1 · Post by **shaunlfc1** » 03 Sep 2010, 19:35

Well I whacked in a new fuel filter the very evening the noise first happened, the old filter, was a bit discouloured but not that bad at all.

Is there any other problem with the fuel filter housing that could cause this problem?

How big of a job is to get the strainer out of the fuel tank to check?

Cheers,

Shaun

MikeT · Post by **MikeT** » 03 Sep 2010, 20:58

That fault is certainly timing related. Did you check the coolant sensor and timing in the Live Parameters section of Lexia?