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  #1  
Old 12-21-2005, 03:58 PM
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What are symtoms of a bad coil?

I have heard coil failures are not uncommon. My vehicle is a 98 and so far, the coils have been fine. had plugs replaced at 75000 miles (feb 05), and was wondering what to expect or how to recognize a bad coil.

my engine runs great other than a few occassional episodes (5.4liter) whereby the rpms go erratic, dropping off to near stall before resuming normal idle. The other thing is, sometimes, though not commonly, the motor runs very rough and lacks power. this is only temporary as well and the computer or motor adjust and resumes power, smoothness and acceleration. not sure what causes any of this.
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  #2  
Old 12-22-2005, 05:03 AM
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Old 12-22-2005, 05:47 AM
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Bad coil

6 months ago coil number 4 went bad causing my Expy to run weak just going up hill and sometimes almost stall while in parking position.. I had erratic rpms once under a bad pcv (bad elbow) too. Check turning on your engine and grab you pcv to see what happens; follow the hose to the firewall.



Quote:
Originally Posted by tealboy1
I have heard coil failures are not uncommon. My vehicle is a 98 and so far, the coils have been fine. had plugs replaced at 75000 miles (feb 05), and was wondering what to expect or how to recognize a bad coil.

my engine runs great other than a few occassional episodes (5.4liter) whereby the rpms go erratic, dropping off to near stall before resuming normal idle. The other thing is, sometimes, though not commonly, the motor runs very rough and lacks power. this is only temporary as well and the computer or motor adjust and resumes power, smoothness and acceleration. not sure what causes any of this.
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  #4  
Old 12-22-2005, 09:41 AM
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the #5 coil on my 02 5.4 went bad and would make the truck shudder and shake and throw the check engine light. Expensive SOB to replace, for what it is.
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  #5  
Old 12-22-2005, 07:20 PM
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Question Bad Coil Blues

So for all of you 5.4L people with a coil that's gone bad... how many have had to replace more than one? At what milage did your coil(s) go bad? I'm asking because I took my '00 Lariat in for 2 coils in two consecutive days. With winter and all the demands on my truck that the weather makes and my need for reliable transportation, I'm just trying to gause if I need to be prepped for more coils to fail. Mind you, I've got 233,000kms on my truck...

Steve
Huntsville, Ontario
'00 Lariat S/C 4x4
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  #6  
Old 12-22-2005, 08:19 PM
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I had a coil go out on my 99 5.4 and knew it right away. I didn't think it was fit to drive in that condition. It would shake terribly at any speed, idled rough, and sounded funny.

Is a coil failure always this bad? My 02 5.4 makes a dull thud noise that sounds almost like a dead cylinder, but much quieter and not nearly as violent. It is so quiet, in fact, that no one else can ever notice when I point it out. This usually only happens when I'm on and off the throttle at low(800-1200 RPM) but ocassionally will happen around 2 grand under load. My theory is that one of the cylinders is not firing as strong as the rest, maybe due to a weak coil? For the most part the engine runs and accelerates smooth as silk. The exhaust sounds like it 'flutters' under a heavy load, usually under full throttle.

Just wondering if this is what some of you are experiencing, not the non-drivable condition of a totally crapped-out coil.
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  #7  
Old 12-22-2005, 09:22 PM
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If the coil goes out you'll no it. No power going up slight hills and can tell it's missing at idle. My check engine never came on though. Just had my #4 (passenger side, by the firewall) coil and plug replaced today. $249. I just changed the plugs two weeks ago at 62,000 miles. I don't know if I had anything to do with causing it or just a coincidence. First COP that has gone out on me. I think I might buy a OBC II scanner (can buy them for $40 on ebay) so if I have any problems in the future I can diagnose the problem and service it myself. They charged $80 for diagnosis, $107 for the coil and plug, $40 labor (reasonable), and I think it would have been about $50 in parts at a parts store.
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  #8  
Old 12-29-2005, 03:36 PM
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Wink new coil pack cheap

go to http://stores.ebay.com/CBS-Automotive-Group and you can get 8 coil packs for $88 its cheap since a motocraft one is $100 each. If they are not listed email the guy he will list it for to buy
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Old 12-29-2005, 03:36 PM


 
 
 
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