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

2001 Saturn L100

Tiny

Jrscars

November, 20, 2011 AT 11:11 PM

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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14 Answers

Tiny

rivermikerat

November, 20, 2011 AT 11:20 PM

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.

Tiny

saturntech9

November, 20, 2011 AT 11:35 PM

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?

Tiny

Jrscars

November, 21, 2011 AT 4:10 AM

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.

Tiny

saturntech9

November, 21, 2011 AT 4:32 AM

Does the cooling fan run all the time?

Tiny

Jrscars

November, 22, 2011 AT 12:22 AM

No, the cooling fan cycles as it should.

Tiny

saturntech9

November, 22, 2011 AT 1:44 AM

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.

Tiny

Jrscars

November, 24, 2011 AT 5:35 AM

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.

Tiny

saturntech9

November, 24, 2011 AT 5:40 AM

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.

Tiny

Jrscars

November, 24, 2011 AT 4:58 PM

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.

Tiny

saturntech9

November, 24, 2011 AT 6:45 PM

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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