XM problems.......

XMplory · Post by **XMplory** » 13 Feb 2005, 11:22

Hi everyone, I have just joined this great forum and I am the proud owner of my first XM ! (Had a BX in the past though!)
Its a 92 2.0 i '<i></i>Prestige<i></i>' (auto) model ,aqquired for the princly sum of £200 ! [:D](short MOT plus a few other probs you'll hear about![:(])
The main problem appears to be its horrendous fuel consumption.(roughly 5-10 mpg)[:0][:0][:0]
Before buying the car i was aware that the engine management light comes on after a few minutes as the car starts warming up and that the exhaust backbox was broken on the pipe inlet.
I did not think for a minute that the engine management light being on would affect the fuel consumption this badly otherwise i may not have bought the car (iam aware that there are probably other problems aswell that could affect this i.e blocked air filter and so on).
The engine management light goes out sometimes when driving and then comes back on, however tonight i found that on long periods of 'overrun' the light goes out ,although this just speculation.
Reading on this forum others have suggested the 'coolant temp sensor for the ecu' but i cannot find this anywhere as it is not in the usual place on thermostat housing .Could someone tell me where it is ?
Also i dont know what kind of injection system is fitted to mine. (Engine no. is :- HJ370700***)
Could anyone please tell me how i find out whether its got one of the Bosch systems fitted or Magneti Marelli type? and also whether its got a cat fitted on this model ?
All i know is that its got 'Weber' on the end of the inlet manifold (throttle body?)
The car idles fine and pulls ok but i think it should be better and without driving another i can not tell as autos are usually a bit more sluggish.
The car has also misfired/backfired? once or twice on overrun (i think?) and one night when i was revving it it puffed out a fair bit of black smoke when it misfired/backfired. I must stress that it has only done this (with the black smoke once) and a couple of misfires/backfires in approx 50 miles of town driving.
I can also smell fuel in the engine bay around the injector/inlet manifold area when the car is not running but cannot find ANY leaks in the engine bay, everything looks dry.
Any thoughts please ?

Homer · Post by **Homer** » 13 Feb 2005, 11:55

Prbably no cat on that age, easiest way to check would be to look under the car. Big silencer type thing right up at the front end before the downpipe.
I've had the exhaust break at the same point an a catted BX and a Xantia and it did not cause the diagnostic light to come on.
Might be an idea to get the diagnostic codes read.

Richard Gallagher · Post by **Richard Gallagher** » 13 Feb 2005, 12:51

I agree with Homer, get the diagnostic codes read.
On that age of car I'd imagine a Gunson code reader for £20 will do the job. It may save a lot of time and money so that you don't buy unnecessary parts whilst 'stabbing in the dark'.

NiSk · Post by **NiSk** » 13 Feb 2005, 14:29

With that level of fuel consumption the engine must be running really rough and pumping out loads of black smoke - if it isn't you've got a leak somewhere!
//NiSk

Post by **philhoward** » 13 Feb 2005, 14:37

If its got Weber on the throttle body, then it should have the Weber/Magnetti Marelli injection system...unless someone's put the wrong one on!
If it is doing that sort of MPG, I wouldn't think the Cat would be any good now - they don't like running THAT rich. If the K light comes on after a few minutes, it could be quite a few things; a sensor going open circuit when it gets warm (crank sensors are good for that, Lambda sensor could not be working (only used by the ECU when the engine's up to temp), or the ECu's temp sensor is playing up. That's be my favourites to look at. Given the 5-10mpg aspect, i'd look at the temp sensor first; EGO correction (what the Lambda sensor does) is normally only around 5-10%, but will send the emissions out of kilter.

XMplory · Post by **XMplory** » 14 Feb 2005, 10:04

Thanks for the responces.
Tonight i have discovered a slight fuel leak around the fuel inlet to the fuel rail right near the first injector at the cam end, also the fuel line here and the one before the pressure regulator are quite badly perished so will replace asap.
But surely a slight weep here would not cause such a high mpg and the Ecu doesnt fire in more fuel just due to a slight loss in pressure so i think there must be something else aswell, like the coolant temp sensor...........But can anyone tell me where it is ?[:)]
Also whats the best way to get to the crank angle sensor ?
Do these cars have a knock sensor ?
Does the Magneti Marelli type have a lambda sensor ?
Could it be worn injectors ?
Could it also have slipped a tooth on cambelt ? if so hows best to check this ?
The funny thing is is the more vigerously i drive the car (just stamping on the accel pedal!) the more mpg i get ! ! !
Must be due to more air being sucked in with all that fuel !
In response to 'NISK'S' reply :- like i said the car idles and runs ok thats also the funny thing about this, it just smells quite rich out of the exhaust, no black smoke only once/twice on a misfire or it probably preignited some unburned fuel.

DoubleChevron · Post by **DoubleChevron** » 14 Feb 2005, 10:54

I'd be suggesting you find the temperature sender. It's gotta be unplugged or dead. You see if the resistance is 'open circuit' the computer says "right full enrichment, the motors is a -40degrees C and needs lotsa fuel to run".
Also check the fuel pressure regulator, when it expired on my CX the pressure skyrocketed to much higher than my 60psi guage could read :EEK:
good luck
Shane L.