Plugs and coils not firing

289,357 MILES • 4.4L • V8 • AUTOMATIC
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REARDRIVE
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I have short question, new plugs and coils. Will a battery maybe going bad cause the spark plugs and coils not to fire? Car model above is a 745i.
Jun 27, 2018 at 7:23 AM
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JACOBANDNICKOLAS
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Hi and thanks for using 2CarPros.com.

If the battery is strong enough to crank the engine, it should not have an affect. If you are not getting spark, I would suggest checking the crank sensor. If you have a scanner which reads live data, check to see if there is a signal coming from the sensor. The sensor is located on the bottom right of the transmission bell housing. I have attached a picture for you to see its location.

I hope this helps. Let me know if you have other questions. If needed, here is a general video of using a scanner.

https://youtu.be/YV3TRZwer8k

Again, it is very unlikely that the battery is the issue unless it is basically dead.

Take care,
Joe
Feb 19, 2021 at 5:48 AM
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REARDRIVE
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I had already replace the crank shaft sensor that was not the problem. I notice when I open the car door the inside lights do not come on, but when I hook the charger on the battery about ten to fifteen minutes then I open the door the inside lights come on. I also replace the Integrated supply module. I thank you.
Feb 19, 2021 at 5:48 AM
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JACOBANDNICKOLAS
  • ✓Experienced Mechanic
  • 110,245 POSTS
If the lights only work after the charger has been on it, remove the battery and have it load tested. It sounds like it is bad. Most parts stores will test it for you free of charge. Here is a link that describes how to do it if you would rather do it yourself:

https://www.2carpros.com/articles/car-battery-load-test

Let me know what you find. Keep in mind, if the battery does not have enough power to turn on the interior lights, it cannot start the engine.

Take care,
Joe
Feb 19, 2021 at 5:48 AM
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