new spark plugs

eastcoastLS

eastcoastLS

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just got all my spark plugs replaced for my 2000 LS V8 yesterday. it was running horrible before. i thought it was the valve body but now its not running like it was before the new spark plugs. before it would stumble from 40-100 mph. my car had no history of spark plugs being replaced and at 88k miles i figured it'd be a good idea. the stumbling has seemed to slowly go away. i told the mechanic that if he noticed any oil or water in the plug wells to inspect and replace the valve cover gaskets but he said there was no signs of any oil in there. my guess is my spark plugs were just old and fouled up. how long should you run on the same set of spark plugs anyways?

also i have replaced my front passenger window regulator (window fell in the door). and i have hooked up a 1.2 farad capacitor to my system. just thought i'd share. haven't been hawking the forums like i used to.

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Last edited:
02V8Sport said:
the coils do fail on these cars even w/o oil in the wells.
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ok, but i didn't have the coils replaced, atleast the mechanic didn't tell me he replaced any of them and the receipt just says 8 plugs. the bill was $250 and some change for all 8 plugs installed...
 
The coils can fail without setting a code and making only subtle missfires.

My 2004 LSV8 was in the shop for a few weeks with them trying to pin down which coil was bad. They told me every time they replaced a coil, it seemed like the problem would move to another and not set a computer code. I only felt the problem during light acceleration at just below freeway speed up to freeway speed.

Since my car was under warranty, I guess Ford only let the dealer replace one coil at a time and even tried to blame me for non factory plugs which turned out to be original and a factory installed item. Ford field rep tried to stick me with the bill until it became clear that my car is ALL factory, NO mods.

So yes the coils can fail without oil and it may be subtle enough to not find it with the computer. It is my opinion that the coils are heat sensitive and prone to failure since my problems started on a hot day with me stuck in traffic for an hour and a half.

Also your car is approaching the mileage where I would start to expect come electronic components, like coils, to fail.

Just my opinion and experience with these *&$@!! coils.

Jim Henderson
 
02 V8 LSE here. Had it since new (Dec2002).

86k miles.

Had my plugs replaced around 66k when I noticed the telltale puff of smoke from the drivers side windshield wiper area when taking off from a stoplight. Valve cover gasket was leaking. Gasket replaced. Plugs replaced with Bosch Platinums. No coils were bad, engine has run smoothly/problem free since new. I have two spare coils sitting in the garage that I ordered off of ebay awhile back, but fortunately, not needed yet.
 
hows the cap working out? Mine still gets maxed out sometimes and my amp shuts off. I think i need a bigger cap...
 
the cap barely did anything. the lighting on the car dims less now with it. and the rpm needle doesn't bounce around with the bass loud.
 
if you were running on old and poor efficient spark plugs, could this cause the coil packs to be ruined?

i just drove 12 hours and the car ran fine the whole time until i got to my destination and did some city driving, every complete stop i made the car was misfiring a lot. the motor kept almost turning off it was missing so bad.

when i had all the spark plugs changed my mechanic said the valve cover seals were fine and that there was no oil or water in the plug wells. he did state that the spark plugs were ruined and it was a good thing i had those changed. do you think bad plugs could ruin the coil packs?
 
The coil packs can go bad with brand new plugs. I just replaced mine last weekend. I had two bad packs, so I just went ahead and replaced them all. They had never been replaced and had 92K on them. I also replaced the plugs while I was in there. There was no water or oil present.
 
Scred said:
The coil packs can go bad with brand new plugs. I just replaced mine last weekend. I had two bad packs, so I just went ahead and replaced them all. They had never been replaced and had 92K on them. I also replaced the plugs while I was in there. There was no water or oil present.
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how was the car running before the new plugs and coil packs? how did you know you had two bad coil packs?
 
The car idled fine, but when it hit 1500 rpm, it would start hesitating and missing. I knew that it had to be the COP's from everything that I had read on this forum. I didn't know how many were bad until I replaced them and took the old ones to a buddy of mine. He knew how to test them with a volt meter and he found that two were bad. I bought the new COP's off of ebay a lot cheaper than I could have gotten them at the parts store. I think they were around $240 for all eight of them.
 
Scred said:
The car idled fine, but when it hit 1500 rpm, it would start hesitating and missing. I knew that it had to be the COP's from everything that I had read on this forum. I didn't know how many were bad until I replaced them and took the old ones to a buddy of mine. He knew how to test them with a volt meter and he found that two were bad. I bought the new COP's off of ebay a lot cheaper than I could have gotten them at the parts store. I think they were around $240 for all eight of them.
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I wonder how he tested them with voltmeter. I tried testing with voltmeter and two of mine that had failed tested fine. The dealer said the only way to test them is under load which requires another tester.
 
is it possible to get misfires only in 5th gear?

I can clearly feel it missing at a stop light but I don't understand when I drive super light on the throttle and as soon as I hit 40 mph and the tranny hits 5th gear, the car all of a sudden starts stumbling all over the road. another thing is the car runs amazing when you get on it. it's when the car is driven easy that it starts stumbling all over the road.

so do you think its possible for the vehicle to only misfire in 5th gear?

this has been an ongoing problem and never has my car thrown a check engine light nor are there any codes stored in the computer.

I recently had all the spark plugs changed because the car was running even worse. should I follow the O.M. on disconnecting the battery since I haven't done that since the new plugs?
 
When I was having problems with my 04 V8, it was usually in 5th cruising at about 40-maybe 55. You could feel a stumble, even my wife noticed it.

Depending on how bad the coils are, you might not feel the stumble if the engine is reving hard. This is probably due to plenty of noise and the stumbles are maybe too short to feel when the engine is at high RPM.

Jusat my experience.

Jim Henderson
 
original coils except for 1 that the previous owner had replaced. 2000 V8 90k.
 
well my check engine light actually works. haha never seen it come on before but its on now. P0302 cylinder 2 misfire. i just put all new plugs in so i guess i'll replace all the coils and see if that clears things up.
 
I don't understand when I drive super light on the throttle and as soon as I hit 40 mph and the tranny hits 5th gear, the car all of a sudden starts stumbling all over the road.
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The gear doesn't matter, its the fact that the engine is under load and running low rpm. My cars been getting progressively worse with the same issue for about the last month. I know what the problem is I just don't know which coil(s) to replace yet. I have an idea, but i've been too lazy to rip into it and replace the ones I think are on the way out. And its been too damn hot.

Anyway, put the gear shift in 3 and give it about half throttle up a steep hill from a stop. I can almost promise you it'll misfire like hell.
The coils are just cheap, they'll die for no reason. You can get them for about $50 a pop from autozone, and replacing all of them takes about an hour tops.
 
update:
just replaced all the passenger side coils and now i'm getting codes P0301 and P0351. any ideas? i don't understand, 8 new spark plugs and 4 new coils on cylders 1-4 and yet i'm still getting a misfire for the same side. any help appreciated..
 
I don't know what the P0351 code is.
I've read that sometimes the computer isn't quite accurate in determining which cylinder is misfiring. Try moving one of the coils to a position on the opposite side of the engine (5-8) and see if it changes anything.
 
my exhaust on the passenger side is weaker than the driver side.....
 
A friend and I replaced one, and I still had a misfire. I got all 8 replacements and we did use dielectric grease on the ends of the coils that meet the spark plugs. That and we replaced all 8 spark plugs. Oh, and of course the valve cove gasket issue. Works great. No misfires.
 
Update

took my 2000 LS8 to the dealer.. apparently i had a faulty cylinder 2 coil. the car threw a check engine light with 2 codes p0301 and p0351. with those codes and the car running terrible the dealer was able to pinpoint it to the cylinder 2 coil. also the dealer said there was carbon built up in the throttle body and the valves which led them to perform fuel injection service to clean the fuel injectors and also performed a three step complete fuel system cleaner, a valve induction cleaner.. the car was also only blowing cold a/c when i was driving or cruising, when i would come to a stop it would start blowing hot air even tho a/c was on, dealer told me that when it misses it sometimes can't build enough pressure for the a/c to work properly, so now my car runs great and the a/c is good.
also told the tech to let me know if any oil was present and if there was to replace the gasket, but none was present..
 
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