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Thread: Help? Car won't start - don't think it's battery

  1. #1
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    Help? Car won't start - don't think it's battery

    Guys:
    Was going to put a new battery in this afternoon just for preventive purposes (car is 02 and had heard they only are good for around 4 years). Car will not start. Current battery "eye" shows green (according to manual this means it's charge and OK) - it has been on a BMW battery tender since I bought the car.
    When I turn the key all interior lights come on and I can hear a click that may be the starter solenoid, but starter doesn't turn over. Also, right front headlight flashes once.
    Thought it might be something to do with car's security system, so used key to lock/unlock doors (no change).
    Thought maybe somehow the key had been deactivated, triggering vehicle immobilizer, so tried other key (no change). As it's 3 on Friday and my dealer is 60 miles away, any ideas on what the problem could be? Thanks for your help.

    Mike

  2. #2
    Team Z8 KenZ8's Avatar
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    Had a similar problem

    with our 325Ci- The battery was reading OK by the green indicator and the lights worked, but the starter wouldn't turn over and we had various lights blinking on and off as well as the fan motor going on and off. It started with a jump from another vehicle, and has worked fine since with a new battery. Good Luck!

  3. #3
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    Thanks!

    Mike

  4. #4
    Administrator thegunguy's Avatar
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    The Z8 is apparently very particular about electrical power. The battery has to be at near peak charge for it to start - thus the supplied tender. Your replacement battery is probably a little low on charge, even though it shows "green".

    Ken's suggestion about jump starting will likely work. Alternatively, you can let the car sit over night with the tender. It should fire in the AM.

    Good luck.
    thegunguy

  5. #5
    Z8Mania
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    its your battery- its shot.

    Think about how much charge it needs to make the green indicator light green and how much is needed to turn over your car.

    If you try to jump it from the jump terminal in the engine it will not work. You need to jump the car at the actual battery. However, your battery is so far gone that it will not recharge when you drive it. So if you need to go somewhere, like to the dealer for a new battery, be prepared to either have them install it right there or get jumped again. I just drove to the dealer and had them put it right in.

    The batteries last about 4-5 years. Preventative maintenance I think everyone should do is replace the battery every 5 years and also every 3 years have the MAFS checked (mass air flow sensor (there are two)). There is no way for you to know how the MAFS are doing unless you have diagnostic tools- the easiest thing is to report to the dealer that the car feels down on power and you think its the MAFS- they get dirty a little too easily in my opinion. If you are under maintenance then they should be replaced free of charge to you. If not each one will cost aprox $350. Pricey- but when I got mine switched out it felt like a new car. They are critical to the performance of the engine.

    So if you are going to the dealer for a battery, you might as well have the MAFS checked too.

    Hope that helps. Happy motoring!

  6. #6
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    MAFS and battery replacements

    Jerry

    How many miles on your car and how has it been driven?

    Mine is an 03, purchased in Jan of 03, and it has 8500 miles. It has the heater problem, but other than that it is flawless. I have been using the Smart tender for a couple of months, but it has never been slow about starting. It does not generally sit undriven for more than a couple of weeks. Three or so at the most. It now has a stable mate to be driven from time to time, and I am concerned about damaging the frame: : , so it may sit a little longer than before - that's why I bought the tender.

    I do have a question about the MAFS. Why did you check them and how many miles did you have on them when you decided to check them? When do you think that they started to make your car run rich? Did you use an 02 sensor or did the car just feel down on power or was the milage bad?

    Thank you for your information

    Hap

  7. #7
    Z8Mania
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    Hap,
    Humm- my car now has about 23500 miles. I drive the car mostly in the warmer months but I do drive it year round. During winter it will sit for sometimes weeks at a time. The record for sitting is 3 months straight. It would be hooked up to a battery tender- but this was not the case until the car was 3 years old.

    When I drive the car I drive it hard.

    As to the MAFS what happened is the battery died and it died right about the time I usually do my inspection- well the car and the NYS inspection computer didnt want to get along. The solution was to replace the DME. So we replaced that and when I test drove the car afterward it felt very down on power. Very very down. The tech agreed with me that it was not simply the DME having to break in so he did some diagnostic tests and discovered the MAFS were not reporting the entire airflow. I believe if you get one of those OBD readers you can get the MAFS data. It has to be within a certain range- and if its reading substantially below that means the sensors are dirty. They self clean, but they cannot keep up and over time its a losing battle.

    On the E39 M5 you could bring up a hidden menu to show you the data but I do not think there is such a menu display.

    From reading on the topic it seems to me that every 3 years or so or every ~20,000 miles is a good time to have the MAFS checked.

  8. #8
    DSC Off hapc's Avatar
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    Thanks very much

    for the information.

    Hap