bad coil pack? motor missing/sputtering..i'm lost!

mamatried · Nov 18, 2007

hey guys i just bought a 2000 GT and all of a sudden the motor started runnin funny, kinda like its missin. at first i thought bad gas but i've filled up since and it won't go away. i noticed one of the COP's (coil pack) had worked its way up cause the bolt holdin it down was broke so i thought, well thats the problem. i made sure it was down in there good this time but it didn't help. could this coil be bad. i checked the ohms on it and it was like 0.6 or 0.7, the same as the others. could it still be bad even if the resistance was ok? i took a screwdriver and listened to the injectors thru it to listen for a clicking sound to make sure the injectors were workin and they all sound fine. but after messin around with the motor, unpluggin COP's here and there with the motor running, i never did get a trouble code. shouldn't i get a misfire code or something. my diablosport tuner didn't show anything at all. isn't that kinda weird? i need help cause i just bought this car and i'm not familiar with the 4.6 yet.

Todd00GT1 · Nov 18, 2007

Does your car have an aftermarket air intake on it? If so, make sure it's connected good up by the throttle body. If it's loose and "un-metered" air goes in thru the TB it can cause the engine to "sputter/miss." I had that happen with my cold air intake this past Summer.

mamatried · Nov 18, 2007

hey man thanks for the quick reply! no it still has the stock air inlet on it. the motor is completely stock as far as i know..other than a 75mm BBK throttle body. when it first started doin this it would run smooth at low rpm's and once i gave it so much gas it would sputter bad. but now it just does it constantly. the best way to describe the feeling would be like a constant vibration. if i smash the pedal in fifth gear at like 50mph i can feel it really bad.

Todd00GT1 · Nov 18, 2007

I've had coil problems with my LS and the check engine light came on. I also developed a vacuum leak and the LS was sputtering badly, but the check engine light came on then also.
How many miles are on it? Maybe new coil packs and plugs wouldn't hurt. I ordered Accel coils and NGK plugs from www.rpmoutlet.com the other week for $213 shipped.

mamatried · Nov 18, 2007

i thought about replacing them but the car only has 75,000 miles. when do the coil packs usually go bad or need to be replaced?

mamatried · Nov 18, 2007

has anyone had a problem that sounds like this....or if anyone has had a bad coil what were the symptoms? i don't want to spend $200 with new coils and plugs and have the same problem! i put a new fuel filter in so it can't be that. i found a black wire coming out of the fuel injector wiring harness that wasn't hooked up. its back by the last cylinder on the drivers side. it looks like a ground wire with a 90 degree rubber boot on it. anybody know where it goes i put on a bolt on the intake it seemed to fit good but i don't guess it has anything to do with my the engine is running funny.

tomustang · Nov 18, 2007

mamatried said:
i thought about replacing them but the car only has 75,000 miles. when do the coil packs usually go bad or need to be replaced?

well past 100K

Have you checked the IAC? pull it off and blast some cleaner in it, it might just be clogged, if one of your coil packs were bad you'd only have 4cyls running

Last thing you posted, can you get a pic of this wire and where it's located?

mrvax · Nov 18, 2007

Does it still have the OEM gas filter?

mamatried · Nov 18, 2007

i just replaced the gas filter a couple months ago so i'm good there. the old one was filthy by the way. i thought about the iac being dirty...i'll go ahead and try that. but would it make the car run funny all the time even under full load?

crzyhrse99 · Nov 18, 2007

Change youre plugs before you spend a lot of coin on coil packs. If that coil pack was loose you have probably got some water down in there to foul that plug. I've had this problem numerous times, now i never wash my engin bay. It will usually throw a missfire code, but the last time my car was missing it wouldnt throw a code at all. After I put in new plugs all was good, hope this helps, plugs are cheap so i'd start there.

2000fordstanggt · Nov 19, 2007

crzyhrse99 said:
Change youre plugs before you spend a lot of coin on coil packs. If that coil pack was loose you have probably got some water down in there to foul that plug. I've had this problem numerous times, now i never wash my engin bay. It will usually throw a missfire code, but the last time my car was missing it wouldnt throw a code at all. After I put in new plugs all was good, hope this helps, plugs are cheap so i'd start there.

exactly. this is what ive been thinking the whole time ive been reading this thread. i would start with the plug that had the broken bolt on the cop.

DogVomit · Nov 19, 2007

I had a similar problem.
Turned out to be a leaking intake manifold.
The leak is a failry common problem.
What happens is the internal leak up by the thermostat allows just enough coolant to drip back into the plug shaft/s on the drivers side plugs, to short the plug/s. It normally gets worse as the motor warms up.

Without removing your fuel rale, you should be able to pull the cops. If you can't blow out the plug shaft and are affraid to remove a plug, just tape a peice of paper towel to a coat ahanger (really good) and push it worn to the bottom of the spark plug shaft.

Take a look at the first 2 spark plug shafts to see if there is coolant, or any other moisture in the spark plug shaft. If so, you may have a leaking intake, or perhaps just moisture in the shaft. You could clean them out, keep the motor dry and see if it comes back in a day or 2, then you might be looking at an intake.

I would replace the original with an aftermarket instead of OEM. Not for power though, Ford really nailed the design of the intake well. The flaw is the crack they tend to get up by the thermostat housing. I replaced with an aftermarket which is the same design, but supposedly one that doesn't crack like the OEM.

mamatried · Nov 19, 2007

thanks for the replies guys! for such a small problem i sure as heck learned a whole lot more about my new car! i started my engine and unplugged the coils one at a time and everyone pulled the motor down except for the coil on #8 cylinder. so i thought well that coil is bad. the next thing i did was reinstall my original tune. the performance tune i had with my Predator Tuner was keeping the car from getting codes i guess..so i put in the original tune and BAM....#8 cylinder misfire. i pulled out the coil and the hole was full of water. i dried it out really good, dried the coil and put it back...it runs like a new car now! i couldn't believe it i'm so freakin relieved. i guess i'll just have to check it again and make sure its not still fillin up, i really hope i don't have a crack somewhere. now i know what to check first next time this happens...thanks for all the help people!

mamatried · Nov 19, 2007

oh i forgot...the hole that had the water in it wasn't the one that had the loose coil pack. the coil pack in this hole was down in there tight...i have no idea how water would have got down in there past the rubber seal on the coil boot...any ideers??

crzyhrse99 · Nov 19, 2007

Like I said earlier, ive had lots of problems w water getting to the plugs. If you wash youre engine make sure you get those COP's covered up along w the other electrical parts. Hell i even had to silicone the underside of my fake hood scoop (dont have hood liner) because when it rained it leaked enough to get water to the COP's.

Glad it was an easy, painless fix for ya.

BurningRubber · Nov 19, 2007

That seal is tight but dirt and moisture can still work its way down there, especially if the boot is frailed or brittle.

Coolant doesnt just get there, its leaking from somewhere. Sound like your standard Ford engineering at work, lol.

2000fordstanggt · Nov 20, 2007

crzyhrse99 said:
Hell i even had to silicone the underside of my fake hood scoop (dont have hood liner) because when it rained it leaked enough to get water to the COP's.

i remember when i took the hood liner off. thats when all of my mis-fire problems started. needless to say i put it back on.

BobHyatt · Nov 21, 2007

BurningRubber said:
That seal is tight but dirt and moisture can still work its way down there, especially if the boot is frailed or brittle.

Coolant doesnt just get there, its leaking from somewhere. Sound like your standard Ford engineering at work, lol.

sounds like the classic water-crossover plastic intake manifold developing a crack letting coolant run onto the top of the motor and into the plug wells... seen it more than once..

Mike97gt · Nov 21, 2007

I did not see this thread untill after it was resolved, but we see this all the time at my work..

99 percent of the time if you have a bucking under acceleration then it's a plug/coil problem.. I can not even begin to explain how common it is for these coils to go bad or get water in the wells...

I have been working on fords for 7 years now and I do a lot of check engine lights and driveablity problems and the amount of fords with these symptoms that it was not the plugs/coil that I have seen has been very small..

The next highest cause of a misfire I have seen on the modulars is valve related. I have one run into a few bad injectors.

the new 3v motors is a different story.. those things fuel foul plugs due to faulty injectors and if you go a long time on oil changes the passeges for the VCT get pluged up and that gets fun.

mamatried · Nov 23, 2007

yeah i've looked around for cracks in the intake but i can't see anything noticable. i finally got it running good and its not missing...but after driving around i noticed some steam coming from under the hood when i parked it, and it definitely smelled like antifreeze. i popped the hood and there was a little moisture around the coil packs on top the motor but couldn't see where it was coming from. i did notice though, that behind the timing cover i could see water puddled up in behind there somewhere. its hard to see back in there so i can't tell whats goin on. it didn't look like antifreeze but more like dirty water...of course thats what was in my spark plug hole too, it didn't look like antifreeze but maybe thats what it was.

bad coil pack? motor missing/sputtering..i'm lost!

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