WHY WONT THE CAR START ON A NEW COIL BUT IT WILL THE OLD ONE? AND IT MISSES.

  • Tiny
  • Jrscars
  • 2001 SATURN L100
  • 95,000 MILES

Recently the car would not start and I diagnosed a bad ignition module. I replaced the module and the car started and ran fine. A couple days later it developed a light miss. It randomly but very regularly coughs, sometimes its bad, sometimes its not too bad. I did a basic tune up with plugs and a fuel filter. No change. I finally decided my coil pack was faulty, so I got one, it will not start at all on any new coil. I got one from the parts store and from the dealer. It will start back up on the original one, but still misses. I dont know what to do. Any thoughts on why no coil will work with it? Thanks.

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Sunday, November 20th, 2011 AT 11:11 PM

14 Replies

  • Tiny
  • Rivermikerat
  • MEMBER

Could be a bad connector or a defective coil. New parts being defective are rare, but they happen. Make sure the crankshaft and camshaft position sensors are functioning properly, as well.

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Sunday, November 20th, 2011 AT 11:20 PM
  • Tiny
  • Saturntech9
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Just to add to this one does it only miss at idle or thru out the rpm range?Those engines that year are known for jumping timing chains?

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Sunday, November 20th, 2011 AT 11:35 PM
  • Tiny
  • Jrscars
  • MEMBER

Thanks for the quick replies. I ruled out the cam sensor because it wouldnt be so specific to which coil pack was on it, but maybe I have 2 problems. The car has most of its coughing at idle, worse in gear and with ac on. Off idle its much better, almost not noticeable.

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Monday, November 21st, 2011 AT 4:10 AM
  • Tiny
  • Saturntech9
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Does the cooling fan run all the time?

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Monday, November 21st, 2011 AT 4:32 AM
  • Tiny
  • Jrscars
  • MEMBER

No, the cooling fan cycles as it should.

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Tuesday, November 22nd, 2011 AT 12:22 AM
  • Tiny
  • Saturntech9
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At the dealer they sold you a single coil?When I worked at the saturn dealer they only came as a coil cassette both coils housing etc without the ignition module.

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Tuesday, November 22nd, 2011 AT 1:44 AM
  • Tiny
  • Jrscars
  • MEMBER

Yes, to clarfy, I am refering to the coil as singular, but it is the assembly you are refering to. The module was replaced first when it had no spark at all. I have since run fuel injector cleaner through the injectors to rule them out as a problem, sure enough, no change in the miss, worse when its cold and/or under load.

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Thursday, November 24th, 2011 AT 5:35 AM
  • Tiny
  • Saturntech9
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Ok so you replaced the coil cassette/assembly are you sure you didnt get a bad module?Because you said it went from a no start to runs great to now runs poorly.

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Thursday, November 24th, 2011 AT 5:40 AM
  • Tiny
  • Jrscars
  • MEMBER

No, im not sure its not a bad module, just thought it was unlikely. My next step was going to be to find a coil assy off of the same car and try it. I can do the same with the module.

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Thursday, November 24th, 2011 AT 4:58 PM
  • Tiny
  • Saturntech9
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Thats a great idea I keep a spare coil cassette complete with module for a quick swap out makes trouble shooting a lot faster. Keep me posted on what you find.

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Thursday, November 24th, 2011 AT 6:45 PM

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