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Thread: sensor values: help please

  
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    sensor values: help please

    hi

    I have a zafira 1.8 that was diagnosed with a duff cat.

    I have changed it out and it has made a big difference but not perfect.

    I have connected my elm scan and get

    air intake temp: 71c
    Cat temp 300 at idle but shifts to 600-700 and 1200 I floor it.
    coolant reported at 95c
    long term fuel at 99.967%
    short term varies between 91-98%
    O2 sensor voltages between 0.3 and 0.8



    The engine feels real hot and the coolant was bubbling in the expansion bottle.

    Is this normal??

    Thanks

    MIke

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    nope, probably an airlock or backpressure in the coolant. even a restricted/blocked radiator.

    Either way the coolant shouldnt bubble/boil. engine being hot is normal. (shouldnt really go over half way on the gauge though, fans should kick in if it does)

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    Air intake temp 71c? Surely that couldn't be right?

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    Make sure your coolant is mixed correctly, and as said before their is probably an air lock or a leak as water needs air to boil, and a coolant system is pressurised so it shouldn't happen.

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    Thanks guys,

    Discovered why it was boiling, 10 mins later it was all over the floor!!

    In my struggle to remove the cat, I somehow managed to loosen the thermostat flange

    Now tightened and full of coolant, but still seems to be pretty hot, no bubbling though.

    Fan cuts in and out the gauge goes just over half way.
    OBD reads coolant at 96c. (seems too hot for me)

    The main thing I am concerned about is destroying the new cat if there is an underlying problem.

    It runs really hot. 300c on idle and way upto 900c when revved, this is according to the obd. Is that right????
    Air intake was now at 45c thats a bit better right

    would appreciate some feedback on the cat though.

    cheers

    mike

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    Any error codes at all?

    I'd replace the thermostat in any case. Coolant shouldn't be getting that hot. Even if it was in a preheat stage (where the cars purposefully overfueled to bring the CAT temperature up). The CAT has no coolant contact its not cooled at all by the coolant.

    What it could be...
    HOS1/2 (Heated oxygen sensor 2) either unplugged or damage and is misreporting to the ECU which is compensating by upping the CATs temperature.

    Engine coolant temperature sensor (tells the ECU that the engine is cold and the ECU compensates by burning more fuel to bring the temperature up).

    Air blockage in the coolant system

    Coolant pump buggered (doubtful as I'd expect you to have a huge failure).

    Hope this helps a bit.
    jam
    Its a jam thing

    Haec credam a deo pio, a deo justo, a deo scito?



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    Thanks jam

    The car was running lean according to the exhaust gas analyzer on the mot.

    No codes that I can read with my elm. but the tuning centre diagnosed cat efficiency. but didnt give me a number.

    Where is the 2nd sensor located? I will check it out and let you know.

    Also does anyone know the correct part number for the thermostat housing? (zx18E 2001) VX pulled up two and couldnt figure out which one it is.

    thanks for the help

    mike

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    Hi Mike,

    Right the Z18XE has 2 heated 02 sensors (lamba) one on the exhaust manifold itself and another one on the exhaust itself near the back of the engine bay.

    Give LMF a call they should be able to sort you out with the right price and part. www.lmfvauxhall.co.uk

    jam
    Its a jam thing

    Haec credam a deo pio, a deo justo, a deo scito?



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    Thanks Jam,

    I ll call them tuesday

    cheers

    mike

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