Engine Sensors

Discussion in 'Ask for help with your car and FAQs' started by ibiza owner, Feb 13, 2006.

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  1. ibiza owner

    ibiza owner IBIZA Mk3 1.0Ltr MPi

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    Hi. Does anyone know what sensors work and report back to the ECU at the stages of starting up the engine from cold to Normal Temperature?

    I have a feeling that I might have a faulty sensor (hoping its not an ECU problem!) as I have problems at about 5 minutes into a journey but only when the engine is started from cold. The engine 'kicks'/misfires once' as I say only happens when engine is warming up.

    Doesn't do it if engine is already warm and I go out in the car - very strange.

    Also what sensor(s) send back info to the ECU to say that its warmed up enough to turn the choke or fast idle off (if it were a normal carburettor engine but it isn't!) :) because maybe this is faulty.

    There is one sensor on the drivers side underneath the Throttle Body and its going into a black plastic housing its held in by 2 torx screws what does that do? its about the best I can explain it at the moment. Next time I get a moment I will take a photo of it and post it up on here

    Any advice please on any of the sensors? - I wish I could get a Haynes workshop manual on these car but unfortunately they don't produce one saying that they don't produce manuals if the car has not sold enough quantity to make it viable to bring out a manual! :censored:

    My car: Mk3 SEAT IBIZA Bog standard 1000cc MPi (multipoint Injection Engine) Year 2000.
     
  2. m0rk

    m0rk sarcasm comes free

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    it'll be the coolant temp sensor, not sure where it is on the 1.0, but if it's faulty it will log a fualt code, and may show an engine warning light.

    try following the coolant pipes back to the engine & look fot electrical connectors going into it.
     
  3. ibiza owner

    ibiza owner IBIZA Mk3 1.0Ltr MPi

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    Thanks for your reply Mork but I replaced the coolant temp sensor last summer on the engine. Had to get one because one minute the gauge on the dashboard would be on cold even though the engine was warm and then the next it would shoot up to normal temp on the gauge and then the next time I looked at the gauge it was back on cold again - very temperamental.

    I bought a new temperature sensor/sender unit from SEAT's put it in myself and that sorted the gauge out and stopped it mucking about.
    There wouldn't be another coolant temperature sensor lurking somewhere else on the engine would there????
     
  4. ibiza owner

    ibiza owner IBIZA Mk3 1.0Ltr MPi

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    Here is a pic of that sensor I was trying to describe. I think maybe this is the MAF or MAP sensor maybe?

    Its got a Bosch part number on it: 0 261 230 031

    inside the cage bit its got like a kind of ceramic like temperature component

    If this sensor was at fault could this be sending back wrong info to the ECU and making the car act up as its warming up?

    If I had to replace this do you reckon its an expensive sensor - will one from a scrap yard do?

    Thanks,

    Andy.

    [​IMG]
     
  5. m0rk

    m0rk sarcasm comes free

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    Inlet air temp, or manifold air temp sensor that is.....

    If it's faulty it will log a fault - shouldn't be too dear at all really
     
  6. ibiza owner

    ibiza owner IBIZA Mk3 1.0Ltr MPi

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    Thanks. Has never shown a fault on the diagnostics machine at SEAT's but they did list a no signal / intermittent /implausible fault on G28 Engine Speed/ Crankshaft sensor.

    If its just this G28 sensor only that is at fault I cant understand why the engine only plays up when the engine is going from cold to normal temperature only.

    Andy.
     
  7. m0rk

    m0rk sarcasm comes free

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    Clean the connector, reset the fault code & I bet all will be well.
     
  8. ibiza owner

    ibiza owner IBIZA Mk3 1.0Ltr MPi

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    thanks, someone else mentioned that once. I did have a look once but could not even bloody find the G28 sensor!

    Can you see it from the top of the engine with the bonnet up or do you have to get to it from underneath the car do you know?

    Thanks.
     
  9. m0rk

    m0rk sarcasm comes free

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    standing in front of the car.

    It will be on the lower right side of the engine block, very close to the gearbox - it will take it's readings from teh crankshaft.

    it might be worth removing the sensor & cleaning it up a bit - when mine logged that fault it was all covered in bits of steel shards that had been drawn to it. I also WD40'd all the connections I could.

    best to get at it from under the car, most likely obscured by the front engine mount.
     
  10. hocrss

    hocrss Guest

    engine coolant temp sensor & coolant temperature sender are two different things.The first sends a signal to the ECU for fuelling purposes,the second makes the temp gauge work.
     
  11. ibiza owner

    ibiza owner IBIZA Mk3 1.0Ltr MPi

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    So do you reckon I have 2 coolant sensors on my car then? - the one I have replaced is at the top of the engine near the ignition coil. Although it looked like 2 sensors could fit into the housing there one was blanked off and the sensor was in the other one. with the funny black plastic U clip that holds it in!
     
  12. hocrss

    hocrss Guest

    let engine warm up then disconnect sender, if temp gauge drops down then you have got wrong sensor-this only operates the gauge
    disconnecting the coolant temp sensor while the engine is running will usually put the engine management light on
     
  13. ibiza owner

    ibiza owner IBIZA Mk3 1.0Ltr MPi

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    Thats the thing, I only reckon I have one coolant temperature sender on my engine and not another one and if I pull the wire off then the temp gauge goes to cold and no EPC light goes on.
     
  14. ibiza owner

    ibiza owner IBIZA Mk3 1.0Ltr MPi

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    Is this where the Crank sensor is?

    I had my Seat Ibiza in bits today to try and find this Crank/engine speed/G28 sensor today and was wondering if this is it in the following picture? - if it is in that location it will look like I will have to remove the starter motor to get to it properly, wonder if the starter motor will be a bitch to remove or easy enough? its only held in by 3 bolts isnt it?

    [​IMG]
     
  15. dan-ish

    dan-ish Audi Techie

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    Thats a map sensor.
    Is it a single cylinder missfire like ignition?I have known coils to short to the body at certain temps then be o.k when warm
     
  16. ibiza owner

    ibiza owner IBIZA Mk3 1.0Ltr MPi

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    Could be although nothing showed up on the garages diagnostic machine about the coil when they checked it. The only faults logged was G28 implausible/intermittent and battery voltage too low (although I had the battery disconnected for a while so that could have been that problem)
     
  17. dan-ish

    dan-ish Audi Techie

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    Coils don't always bring a fault code untill there open cicuit or a diffenet missfire detected.
    It does sound like it would be the crank sensor if it's come up as a fault code your picture is a bit hard to see but it does look in the right area.
     
  18. ibiza owner

    ibiza owner IBIZA Mk3 1.0Ltr MPi

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    Thanks. Yes, sorry about that, it was a bit difficult to get the digital camera into that space.
     
  19. ibiza owner

    ibiza owner IBIZA Mk3 1.0Ltr MPi

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    Thats a point, does the ECU normally log/store a coil fault or are coil fault codes not logged in the ECU?
     
  20. ibiza owner

    ibiza owner IBIZA Mk3 1.0Ltr MPi

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    I removed this sensor off the engine as well whilst I was at it today. I am almost sure this is called the Knock Sensor but some people call it an Engine speed sensor. Its a bit grubby and I will clean it up now its off but does anyone know what effect it would have on the car if it had a fault?

    Could it cause the engine to cut out a few minutes of Idling on the drive or cause the engine to cut out a few minutes into driving when the engine is warming up?

    [​IMG]
     

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