Help! Please. Xantia 1.8 cutting out.

[dowen]

My 16v xantia drives really well, then, without warning it just cuts out, It can be alarming when overtaking on a motorway, or at junctions etc. Then immediately comes back to life. It is just as if the ignition had been switched off and on, not just one cylinder, the lot. Ive changed all plugs, and the coil pack, made no difference. So, I had a £40 diagnosis, it came up with a faulty inlet manifold pressure sensor! The mechanic wasn't too sure, although he was sure it was 40 quid, thank you very much! Has this happened to any one? I would be very grateful if someone could help Regards, David Owen.

[Deanxm]

Hi David

If the diagnostic says its the MAP sensor then i would guess you will need a new map sensor, im amazed this confused you mechanic though .
not too up on my xantias but i would guess its one of these http://cgi.ebay.co.uk/MAP-Manifold-Air- ... 3ca7f66d26 and at £16 it shouldnt break the bank, easy to fit yourself too.

(Edit) check the rubber hose from the inlet manifold to the map sensor isnt split or damaged first though

Good luck!
D

[DickieG]

I don't think that is the correct MAP sensor, the one mentioned is for the older 1.8 8V, IIRC on the 16V the map sensor is on the underside of the manifold and is a different shape with just one securing bolt.

Quite a common problem appears to be the coil pack which I understand can cause similar effects (bear in mind that 1.8 and 2.0 coil packs are a different shape and not interchangeable).

Also check the two large relays in the ECU box under the bonnet.

[Deanxm]

I did wonder, shame though i bet the 16v one is 5 times the price then

D

[Sid_the_Squid]

I believe there are two MAP sensors for the 1.8 16v, I recently had to buy one, theres a cheap one and an expensive one. AFAIK the only way to be sure which one you have fitted is to take the old one off and actually bring to a parts shop.
The map sensor is a real pain to remove, very awkward.
Mine had the expensive one fitted, came to about £45 from eurocar parts, I'd post a link but cant seem to make their web site work now.

[CitroJim]

I personally doubt the MAP sensor is the total cause of the problem. Usually they cause poor running at low speeds and stumbling but I'd be amazed (but quite prepared to be though!) if it caused a total stall as you're experiencing.

When it does cut out, do you loose any other electrics? I had much the same happen briefly a couple of times ages ago on my Activa and I noted that when it happened all the instruments fell to zero and all the warning lights came on just as you'd expect of a stalled engine. I never did find a positive cause but my suspicions fell upon the double injection relay that will be found as an oblong relay sitting next to the injection ECU. This relay feeds the injection ECU, the fuel pump and the injectors and is operated in part by the ignition switch and the immobiliser. The ignition switch itself is not above suspicion either.

I always carry a spare relay in the glove box these days and since then I have never had a repeat of the problem, touch-wood.

[addo]

Recently, I too experienced similar issues. The only thing which seemed to reduce them (but I'm not 100% sure it's gone entirely) was replacement of the CAS.

Coil pack would just cause a misfire on two cylinders - not a complete shutdown. I'd think a dying MAP sensor might cause a rich (safe) condition with mapping based on intake air temp and the O2 results.

[Thermonuclear]

Had the same problem on my 1998 Mk II 1.8 16V Xantia a few weeks ago. To find the cause I ran a wire from the Engine Managment Computer (Sagem SL96 in my car) to a digital voltmeter in the cabin. Over several days I checked power to the fuel pump, power to the coil pack, and finally the output from the MAP sensor. The MAP sensor output (input to the Managment Computer) varied from 0.5V - engine coasting, 1.4V - engine idle no load, to 4.5V - car accelerating. Intermittantly, the MAP voltage would drop to 0V. Sometimes this had no effect on the car, but everytime the power died, it happened as the voltage dropped to 0V. I checked the 5V power supply to the MAP sensor from the Engine Managment Computer and it was steady at 5V. Twice the 'K' light came on while driving, but reset after engine shutdown and restart. Unlike the Bosch Engine Computers, the Sagem unit does not have a live feed from the battery, it is powered by the double injection realy only. If the tachometer works normally, the Engine Managment Computer and its power supply should be ok. The fuel pump and coil pack are also powered by the double injection relay. Changing the MAP sensor (100 Euro) fixted my problem. However, as Citrojim says, the double injection can cause problems like this. It is also worth noting that an internet search for this problem led to several sites that suggest that coil packs made by Sagem suffer from a fault which leads to HT leaking back to the Engine Managment Computer and damaging it, leading to intermittant runing. This can be very expensive! They recommend fitting a coil pack NOT made by Sagem (ie Valeo, etc.) Citrojim posts wiring diagrams on this forum and I found a Sagem diagram of his here, which was a big help. It sounds to me like you need a MAP sensor like I did, but without measurments I cannot be sure. I found that the problem occoured most often when the car had just reached operating temprature, and if I stoped for a short time (refueling) when it was hot, it would be very hard to restart, and would not idle well. The MAP sensor is well hidden behind the inlet manifold but can be changed. Removing the connector from the oil low pressure switch helped. Its easer to get out then get back in! Its held in by one 10mm bolt. Its connector has a spring loaded latch which is trickey but not impossible. Best of luck!

Hope this helps

DG

[CitroJim]

Let me know if you want the applicable circuit diagrams David....

[dowen]

Many thanks for all your help, I got more help and advise for free,than the mechanic I paid 40 quid! I think common sense tells me it cant be the MAP! that would not make it cut out completely for sometimes 2 or 3 seconds. Ive ordered a MAP £16 on eBay. but I'm looking for a injection relay, that makes more sense.

I only recently bought the xantia, I needed something to get me around as my C5 v6 among many other things developed an oil leak from the steering rack, behind the gaiter, its just a cheap O ring ? Anybody know? Anyway it will have to come off, Some job! The first thing I noticed when I drove the Xantia, was how much more comfortable and smooth the ride is compared to the C5, ...Almost as good as the XM! I had an XM for 4 years no trouble at all. So that's what I'm looking for now. Thanks again for your help. dowen.

[VertVega]

I think common sense tells me it cant be the MAP! that would not make it cut out completely for sometimes 2 or 3 seconds.

When I had MAP sensor problem some years ago one of the symptoms was engine cut off during overtake.

Gear stick into 4 and step on the gas pedal, nice acceleration.
Overtake was almost over and I pressed clutch pedal in order to shift to 5
but as a result engine cut off, all dashboard lights came ON.
I got the engine running again (on the fly) by releasing the clutch pedal (gear in 5).

That WAS my last "exciting" overtake before MAP sensor replacement

[VertVega]

MAP sensor in my Xantia was this type -->


I've seen in Xantia '99 (1.8 16V) where MAP sensor was this type -->


They both have 3 wires on the connector but connector type is different.
I think pin layout is also in different order.

PS: pics are from ebay, I'm not seller, not related to the sellers in any way

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Edit: this's the broken sensor from mine