Aaaaaaarrrggggghhhhh - Damned car!!

[andmcit]

OK, I'll say it, are you listening Robert? My Activa is really starting to p!ss me off!

It's fighting me every step of the way. No, not the fancy suspension but the
bloody engine emissions. It had a nice new (expensive) NGK lambda sensor today
and it made not one jot of a difference. MrMOTman is very sympathetic and hasn't
claimed the retest yet after x3 revisits to get a current reading although this is
getting a bit embarrassing for him as well as me!

IT has had every sensor and plug that I can get near switch cleaned although I now
need to consider the not so easy to get ones too! Probably just the temp sensors.

The problem is covered in an earlier Activa area specific post but I don't see why
everyone else can't add suggestions as I'd love to hear any experiences that match this:

http://www.frenchcarforum.co.uk/forum/v ... 17&t=40357" onclick="window.open(this.href);return false;

It's bad on the CO at fast idle = 1.078 with pass under 0.300 and the normal idle is very low 0.043 pass limit 0.500.
In fact CO seemed to get worse with the Second Fast Idle Test at 1.386. The HC is negligible at 8-11 pass limit 200
and lambda is steady at 1.001-1.004 pass limit 0.970-1.030.

When the car started the test it was hunting at idle and unfortunately that's when the readings were taken - by
the end of the test session after 3/4 of an hour it was really a lot happier and smooth but another reading couldn't
be taken and I wonder what the readings would be then.

The car has stood around 8-10 months little used and MrMOTMan suggested new plugs, fresh petrol and additive
injection cleaner with new oil/filters which TBH I was going to do but not specifically for the test now. He didn't
think the cat was suspect and I'm not sure of the validity of swapping everything in sight. MrMOTMan believes the
ECU is constantly tripping things up by resetting itself and altering the fuelling which is the cause of the wide
fluctuating idle and readings so I guess it could be one input feed sensor. The fuel has been allowed to run right
low as I've had it idling loads in the garage whilst messing about with the ride height/ARCS adjustment and new
middle exhaust section so for the test has had £20 quidsworth of regular unleaded. Would Optimax help?

Has anyone encountered a similar issue on their Activa and/or have suggestions on a fix?

So. Since this post it's had a new set of correct NGK plugs, lambda, air cleaner and a known good working set
of HT leads as well as a fun Italian tune up and Redex fuel injector treatment.

The car passes the idle emissions test and it pulls really well and cleanly and is (frustratingly ATM) a nice drive!
It WILL NOT hold an even idle - no matter what rev in the 1800-2400 range it will hold for a few seconds then dip
or rise of it's own accord which at first you put down to a twitch of the foot to alter the pressure on the throttle.
This is which is shown by the actual yo-yo effect of the emissions readings on the all knowing machine - it will be
in the pass range for around 10-15 seconds then ramp up to 1.6 to 2 in the CO reading as it seems the fuel system
adjusts via the ECU as it (probably) lobs some additional fuel in. Basically, it seems just like a sensor is breaking
down at higher revs due to higher pressure/heat etc?

A pal with a LEXIA is encountering PC issues so as yet it hasn't had the decent thing and had a diagnostic session
and none of the local Cit Indies are free to LEXIA it until middle of next week when the retest will laspe. The car
will have to be mothballed if nothing can be resolved asap as it cannot remain where it currently sits and once
its out of the immediate sphere of influence, less likely to get anything done anytime soon 35 miles away and I
can't keep chucking money at it!!

Has anyone got any advice/relevant anecdotes etc!? It's getting on my tits!

[Lighty]

Have you tried putting the suspension in low, so that the hydraulics are not cutting in every few seconds.
This may be upsetting the idle and hence the co

[Gregg1100]

Hi Andrew,
My 16v Xantia was like yours. Idling all over the shop. Fitted new throttle electronic thing, potentiometer, etc. Turned out to be a leaking inlet manifold gasket- spray some WD40 on inlet manifold, if you can get at it, to see if bubbles appear. Inlet gasket was changed, no more problems.
Greg

[citronut]

if you spray carb cleaner around all induction area's pipes hose's and manifold joints this will find vacuum leaks better the that W stuff,

the other thing to remove is the idle stepper motor,
blast out with carb cleaner, blow out with air line followed by a shot of duck oil or a very light oil like 3in1

[CitroJim]

Andrew, a useful thing to check is the pipe running to the MAP sensor. There was an Info Rapide about this where the plastic part of the pipe could squash where it was clipped to the rubber stub-ends and cause a false pressure reading.

Also, check the rubber stub-ends for perishing and also the white plastic damper box near the ECU end of the pipe. It can go hard and split.

The MAP sensor itself is inside the ECU but hardly ever fails.

I doubt this is the problem though as Lambda and HC are both good. It's more suggestive of the cat having seen off all it's nine lives or...

Else that you have false air getting into the exhaust and fooling the lambda sensor. Check for exhaust leaks upstream of the lambda sensor. You know how these engines just love to blow exhaust manifold gaskets. Check too the 'brillo pad' is not leaking. You'll see soot around it if it is... A blowing manifold gasket will make it sound like a Fordson tractor...

[KevMayer]

I've a distant memory of a problem similar to this and I think it ended up being an oil leak down the valve guides into the combustion chamber.

Could this be the problem

[CitroJim]

I've a distant memory of a problem similar to this and I think it ended up being an oil leak down the valve guides into the combustion chamber.

Could this be the problem

That's more likely to raise HCs Kev. Good test for this would be to see blue smoke out of the exhaust under conditions of high vacuum...

[andmcit]

UPDATE!!

Many thanks for your thoughts here - it's worth my mentioning the car has covered 89,725 miles and goes very well
and I love driving it and really want it sorted!

It has finally seen the attentions of a LEXIA diagnostic this evening and for the ignition brings up:

Permanent Fault Knock Sensor
Intermittent Fault Engine Speed Sensor Signal

First question - where is the knock sensor as I can't see it on the block?
Second Question - I this this another phrase for the flywheel sensor!?

I also seem to have intermittent errors on the electro valves susp ECU and susp fuel system
- does that mean an LHM leak!?

CPH flags up key errors too which is why it beeps on starting sometimes I guess.

So. Would the knock sensor and flywheel sensor hijack the fast idle????

[andmcit]

Reading up on knock sensors and their failure mode would certainly suggest the
mixture would be wrong but there would also be a knocking/pinking evident
whilst the engine runs but there isn't?

[andmcit]

Xantia petrol engines discontinued the knock sensor in very early 1999. The plug is still on the harness, but no provision made for it in the ECU software.

Mine is like this; I've wondered what might happen if one were connected in.

Do I have a permanent failure of the knock sensor because there isn't one fitted then Adam?
My car is registered in Jan 2000...

[xantia_v6]

The knock sensor mainly adjusts the timing, not the mixture, and is mainly active under conditions of high combustion pressure (full throttle), so not likely to be linked to your idling problem. I am a bit surprised if they were deleted from the TCT engine, as that would seem to be one application where it would really be needed.

An intermittent crank sensor could play havoc with idling and emissions, but beware that the lexia may be reporting something that the ECU thought it saw years ago. You need to clear the faults and see if they reoccur.

[andmcit]

Resetting the fault codes still brings the same warnings up so I've had a prod
about the flywheel sender connection and changed over to another second hand
knock sensor so it now only brings up a warning of an intermittent fault on the
knock sensor plus of course an intermittent steering wheel sensor and throwing
a strop as it cannot find the klaxxon siren for the alarm; worryingly, it doesn't
seem to like the look of my key on the CPH computer too!

As a rough rule of thumb, according to MrMOTMan, if it revs and doesn't jack
about at a particular level it will all be OK and it seems to be doing this more now!
OK, not 100% but nothing like as noticeable as before. Basically the revs are keen
and smooth but when they reach a chosen determined level and expected to stay
at the mark the needle will stay for around 10 - 15 seconds then decide to go
ever so slightly on a wander up or down the rev range and that's not because
of the position of my foot on the pedal!

The LEXIA has been handy and I do want to check out the Xant V6 shortly too;
may have to think about the unthinkable and buy a Windoze lapdog as LEXIA
doesn't run on a MacBook Pro.

edit - typotastic!

[handyman]

Andrew, if this is a late car, the throttle body is probably that cheap rubbish plastic item. Check for wear in the throttle spindle and the plastic body. I had this on my 1.8 and it had all the symptoms you expressed. Worth also checking the temperature sensor and the cooling fan wiring, as these are interlinked with the ECU, so it may cause the mixture to wander and give you these strange problems.

I did also find a wear mark in the wiring harness to the temperature sensor, where the insulation had been compromised. Resolving this made the running problems less erratic, but the harness for the 2.0T is different to the 16V in this respect.

If I remember any more points, I'll post up again.

Might be worth taking to the MOT man, outside of the test and asking him to check the emissions on his machine. Saves you the cost of the test and ta least you'll know if its resolving the problem.

Dont forget, change one thing at a time, to find the solution. Do too many things and you wont know what has helped.

H

[andmcit]

Thanks for the thought HM.

It is a late jan2000 car but has an ally manifold. I do have misgivings
about the temperature sensor although was expecting it to show up
on the LEXIA or does the ECU just get what it's given to work with
without asking any questions about the working temp range?

I have had an issue with a poor connector on a temp sensor on a normal
2.0i Xant but the emissions and consumption were globally completely
out of whack not just at higher revs although I guess how it breaks down
may affect different states of poor / incorrect running. The fans cut in
and out fine although of course they run off a different sender of the x3
on the head though I will need to get a closer look (somehow!!) at these
although access is rubbish on the TCT here!

The MOT guy is really cool about letting me have additional readings
although I worry I'm taking the p!ss a bit going back all the time!!

With you on the one change at a time - did that all wrong years ago
on a poor running CX Prestige 2.5...

[steelcityuk]

Hi.

Has the fuel rail pressure been tested? Is it to spec and consistant?

Steve.