will a bad coil pack throw a code?

rickshaw

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I reset my PCM today in an attempt to improve my idle and hesitiation at 50mph.

The idle is better but still is a little rough. At 2K of 50mph the engine sputters like a plug or coil pack is missing.

Will this ever throw a code to diagnose? Or can Autozone give me a read out?

thanks!
 

Ian Macoomb

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I've found that the coils going south are only really noticeable at idle. At any other engine speed they really aren't.

Also, it seems to take forever to get a code for a misfire. If there's no SES light chances are good that there won't be anything for the code reader to pull. However, I have found that I can get pending codes for misfires by starting off from a stop in 2nd gear. Bogging the engine seems to make it more sensitive to the misfires for some reason.
 

rickshaw

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this is driving me nuts! I replaced all the coil packs at 105K, so I'd like to think they are ok. Could this be bad gas?
 

Mr. SHO

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Wouldn't be the first time a coil pack or two died so young. They rarely throw codes (at least not hard codes) until they have been showing signs of failure for a very long time so it doesn't surprise me that you have no codes.

When my coil(s) were going south long ago, it was noticable mostly in very hot weather at idle, but it eventually progressed to the point that the car would start randomly misfiring about 1/2 of the time I went WOT. I would feel surges of power intermittantly, but it was very obviously misfiring. It would actually shut the car down sometimes. Stopping and restarting would usually clear it up temporarily. The CEL would come on only when it stalled (as it always does) and it would shut off once I restarted. I just dealt with it until I took the car to get welded and I had Kirk throw in 4 new coils on the back bank while he was in there. Still OK now some 32K miles later, but I wouldn't be surprised if I had to go through it again before 100K.
 

1slickRED89

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if the coil doesn't fire at all (firing on the outside of the spark plug, in oil or on the valve cover counts as a 'fire'), it doesn't make "back spike" to the DIS. this "back spike", up to a 2-300 volt ripple, is what the IDM signal is built on. the IDM signal drives the tachometer. if you misfire from too wide a gap spark plug, weak coil or whatever, your tach needle will hold when you accelerate, or drop off if its bad enough.

if you don't have a dropping or holding tach needle it's probably spark plug or spark plug wire related. maybe a fuel problem (filter, fuel injector etc.)

even if you don't have a CEL look at the continuous memory codes in a key on engine off test.
 

Mr. SHO

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1slickRED89 said:
if the coil doesn't fire at all (firing on the outside of the spark plug, in oil or on the valve cover counts as a 'fire'), it doesn't make "back spike" to the DIS. this "back spike", up to a 2-300 volt ripple, is what the IDM signal is built on. the IDM signal drives the tachometer. if you misfire from too wide a gap spark plug, weak coil or whatever, your tach needle will hold when you accelerate, or drop off if its bad enough.

if you don't have a dropping or holding tach needle it's probably spark plug or spark plug wire related. maybe a fuel problem (filter, fuel injector etc.)

even if you don't have a CEL look at the continuous memory codes in a key on engine off test.
This is the V8 section. We don't have issues with oil in the wells, we don't have spark plug wires, and we don't experience the tach behavior you describe. :biggrin: Not to say that COP is an "improvement". :nut:
 

1slickRED89

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oops, well thats a primer in old tech then. thanks for letting me down easy.

Not to say that COP is an "improvement".

not on a V6 sho, i'm the second (and hopefully the last) guy to try it.
 

Want.to.be

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My car just had #8 coil replaced and now the car is running like crap again after two weeks.

It is extremley HOT here in Indiana...so the message above makes since why the coils might be failing.

It could possibly be the #8 coild agian or i need to replace all my spark plugs.

The shop wanted $200 bucks the last time i was in for spark plug install...I thought that was WAY to HIGH!

I am in-line @ the ford shop for the repairs. I am hopeful she can get in and be heathly again after Monday.

I hope its the coils....not the cams....

jpc
 
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Ian Macoomb

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It could be that the new coil was a dud but chances are more likely that it's another coil. The coils like to fail shortly after handling for some reason. If the mechanic pulled another coil to see the plug in another cylinder he could have accelerated it's death.

You might want to have the plugs changed if coils are starting to die. I'd also have them gapped on the low side. If the gap is too large the voltage required to fire the plug will be higher. The higher the voltage the higher the current. The high current is causing excessive heat and may be the reason the coils die.
 

SHOZ123

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Buy them from Murray's and get a lifetime guarantee as well as the lowest prices.......
 

rickshaw

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How do you use a meter to determine if a coil pack is getting the proper voltage?

I bought one a few years ago...always wanted to use it!

thanks,
 

SHOZ123

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The coils are fed from a common fuse in the fuse box under the dash. It's fuse #10 a 20A. If you have 12V there then the coils have 12V.
 
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SHOZ123

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If you got tons of money yo take it to the Fud dealer and let them put the WBS or whatever it is on the car.

If not it'***** and miss.........
 

JrodSVT

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Ppt

Ppt4

Ppt1

Ppt2

Ppt3

Pcm1

Pcm2

Pcm3

This is the diagnostic steps for finding a bad coil pack.
I thought you might have been able to just ohm out the coil but that spec seems to have eluded me.
 
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rickshaw

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Finally!!!! I finally got the 307 Error Code! I took 300 miles, but good thing I saved the coil packs from the last change.

Now if I can just fins the ac leak...:oogle:
 

SHO2

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I have a 96 and its throwing a code for the coil packs 2 and 7 are junk. But the funny thing is when the car is idling it coughs,spits and sputters but when I give it gas it smooths right. I replaced the two and rotated them, now the car runs like a top. just my 2 cents:)
 

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