850 engine cuts out

Discussion in 'Volvo 850' started by Marvin42, Feb 22, 2007.

  1. Marvin42

    Marvin42 Guest

    Help! My 850 2.5 10-valve sometimes cuts out on a right turn, which
    is very inconvenient on roundabouts in the UK. The symptoms are: 1-
    the engine dies and will not re-start. 2- the engine cranks but there
    is no spark at the coil. 3- when you turn on the ignition the
    temperature gauge goes right up, then right down even though the
    engine temperature is normal before it cuts out. 4- after about 40
    minutes it will re-start and the temp. gauge works normally. It has
    happened twice now, and after the second time the Lambda light has
    stayed on. After the first time I did 150 miles, threw the car round
    lots of right turns (which was fun) - no problems until yesterday,
    when it died on a busy roundabout. Please can someone help? Or
    should I re-plan my routes to always turn left? Could it be an
    immobiliser fault? (I did try switching the immobiliser on and off but
    no help). Thanks, Marvin
    Marvin42, Feb 22, 2007
  2. Marvin42

    Tim.. Guest

    Tricky one!!

    I would suggest you check the connections at the ignition coil, and
    under-mounted amp, and especially the earth ring connector that is trapped
    under one of the bolts. Remove the coil unit entirely, as its often painted
    under neath and the earth connection is less than ideal electrically.

    Also check the King HT lead is properly restrained in the clips around the
    air filter, and the Air temp sensor wiring is routed as far away from the HT
    lead as possible.

    Also check the Cam Position Sensor (CPS) wiring plug on the end of the
    exhaust cam, and the Crank Angle Sensor (CAS) plug wiring below it.

    I am mystifed by your weird temp gauge readings,- it may well the ECU is
    being spiked by stray HT, but it should restart straight away though.

    Tim.., Feb 22, 2007
  3. Marvin42

    Marvin42 Guest

    Thanks Tim, I had checked the wiring but not the coil earth - I will
    do that. It's tricky to find a fault that has gone...
    Marvin42, Feb 23, 2007
  4. Marvin42

    Mike F Guest

    But it's not entirely gone. You have a code stored in the ECU that
    caused the Lambda light. That code should point you in the correct

    Mike F.
    Thornhill (near Toronto), Ont.

    Replace tt with t (twice!) and remove parentheses to email me directly.
    (But I check the newsgroup more often than this email address.)
    Mike F, Feb 23, 2007
  5. Marvin42

    Marvin42 Guest

    Thanks guys. Today the car stopped again, but I had my trusty
    voltmeter with me. I measured the voltage on the coil: ignition on -
    nothing. Cranking - 12v to chassis on both red and blue wires, of
    course no voltage across the coil. I tried earthing the coil body/
    amplifier heatsink - no change. I don't expect either coil connection
    to be grounded but the fault must be in whatever it is that drives the
    coil amplifier. Time, I thought, to read the fault codes: Socket A
    pins 2 and 3 give 1-1-1, socket B pin 5 gives 1-1-1. None of the
    other pins give any flashes. I hope this means something to
    someone... the temp. gauge was doing the same thing: switch on, the
    needle goes to halfway, pauses for second, then goes right up, pauses
    for a few seconds then falls to zero. After an hour and a half, as I
    was attaching the tow rope, my wife tried the key and she fired up,
    drove home with no problems. I didn't mention it before, but the
    central locking gives trouble in damp weather, especially the
    tailgate, and the remote often will not lock the doors although it
    will unlock them after I have locked them manually. Could this be an
    immobiliser fault? Where is the immobilser located, and can I disable
    Marvin42, Feb 23, 2007
  6. Marvin42

    Tim.. Guest

    No, it wont be an immobilizer fault, as it is inhibited whilst the engine is

    Seeing as you had no +12v at the coil with key on, I would head straight for
    the main relay (underside of fuse box) Sounds to me that the ECU is not
    powered up when it dies. - dry joint in the relay.

    If you can- check for +5v at one of the engine sensors (pin 1 if its a 3 pin
    connector) the next time it quits. If 0v the ECU is not powered.

    Either replace the relay, or open it up and resolder the PCB.

    Tim.., Feb 23, 2007
  7. Marvin42

    Marvin42 Guest

    Hi again just an update... the ECU was still powered because it
    started the fuel pump briefly when the key was turned. Someone on
    another forum suggested the coolant temperature sender - I replaced
    that, and the thermostat as well because you have to remove the elbow
    to get at the sender, and the car has not broken down for 40 miles so
    far (it wouldn't do more than 10 miles before). The only trouble is
    that the idle is now down to 550 RPM hot or cold, and it stalls
    easily.... I think I'll start by cleaning the idle valve, but what
    next? Cheers, Alan
    Marvin42, Feb 28, 2007
  8. Marvin42


    Apr 24, 2013
    Likes Received:
    Pull the codes. It will most likely be the camshaft sensor. I had the same problem, having the engine die for no apparent reason and not starting at all. Replaced the cam shaft sensor and she runs like a charm now. Maybe change the fuel relay while your at it.
    TonyB, Apr 24, 2013
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