My repair guy says i have a bad coil in my 08 Ford Edge. 130,000. Should i have all of them replaced these are the original how much should I pay having a mechanic replace?
Bad coil question
- Thread starter SmokeyBear
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I'd rather go with all spark plugs replaced and failing coil only. I'd guess an hour of work max but plugs need to be changed on cold engine.
Coils fail at erratic and unpredictable intervals. The majority, in fact, never do. I have a car with 333k mile on it and four of the original coils. Another V6 at 200k, all original coils. At 130k all your plugs should have been replaced. Were they (can cause coil wear/failure)?
Replace plug and coil that is bad. Get an OBDII reader and buy a couple of low-mile used salvage take-off coils on Ebay ($30). Then replace them yourself as necessary (if ever).
Replace plug and coil that is bad. Get an OBDII reader and buy a couple of low-mile used salvage take-off coils on Ebay ($30). Then replace them yourself as necessary (if ever).
I have always only replaced the defective coils. It's been over 10 years that I have had one go bad. I would not use an aftermarket replacement.
Coils are a go/ no go item.
Only replace them as needed. One going bad is not indicative on the rest "about to go" as well.
Cheap coils from Amazon/e-bay are a crap shoot. If it is an engine that is easy to change on, not a big deal, but if it is a pain to change them, pay the money for better (usually OEM) coils.
As mentioned, when were the plugs last changed?
A bad plug can cause a coil to go bad, so make sure to at least check the plug on the bad coil and change it if needed, or replace them all if they are older.
I recently had a coil go bad on my son's Scion tC with 155,000 miles on it. I bought a 4 pack of no name coils off Amazon for $37 (cheapest single coil option was $18).
My thought process is change the one bad coil, and have 3 spares for that one. One of those 4 will last the rest of the life of the car, and worse case it takes 5 minutes to change a coil on that car. I literally have a spare coil and 10 mm socket in the back of the car for on the spot replacement if needed.
We did replace all 4 plugs while we were in there. Was told when we bought the car a "tune up" had recently been done, so I (incorrectly) assumed the plugs has recently been changed, when in fact they had not (I don't think they were original plugs, but were old plugs and needed to be changed). The plug on the bad coil had a huge gap, so no idea if that was the cause of the coil going bad or what (had swapped coils to verify it was the coil and the other coil worked fine on the "bad" plug).
Similar for my '02 F150 with 208,000 miles on it. Had an original OEM coil go bad a few months ago. Was #7 coil, kind of annoying to get to. Took coil 7 off and replaced it with the coil from #5 (super easy to get to) and ordered 2 cheapie coils off Amazon. Cheap replacement is on cylinder 5 and again, takes 5 minutes to replace if it goes bad. Plugs had been changed 20,000 miles ago and plug 7 looked fine, so did not change it.
On the other hand, had a coil go out on my BMW K1600 motorcycle with 65,000 miles, and that requires several hours to replace, so bought a known good brand replacement coil. Plugs were replaced 5,000 miles ago, and plug on bad coil looked like new. This bike is known to have issues with coils going bad (a lot of heat packed into a small area).
Only replace them as needed. One going bad is not indicative on the rest "about to go" as well.
Cheap coils from Amazon/e-bay are a crap shoot. If it is an engine that is easy to change on, not a big deal, but if it is a pain to change them, pay the money for better (usually OEM) coils.
As mentioned, when were the plugs last changed?
A bad plug can cause a coil to go bad, so make sure to at least check the plug on the bad coil and change it if needed, or replace them all if they are older.
I recently had a coil go bad on my son's Scion tC with 155,000 miles on it. I bought a 4 pack of no name coils off Amazon for $37 (cheapest single coil option was $18).
My thought process is change the one bad coil, and have 3 spares for that one. One of those 4 will last the rest of the life of the car, and worse case it takes 5 minutes to change a coil on that car. I literally have a spare coil and 10 mm socket in the back of the car for on the spot replacement if needed.
We did replace all 4 plugs while we were in there. Was told when we bought the car a "tune up" had recently been done, so I (incorrectly) assumed the plugs has recently been changed, when in fact they had not (I don't think they were original plugs, but were old plugs and needed to be changed). The plug on the bad coil had a huge gap, so no idea if that was the cause of the coil going bad or what (had swapped coils to verify it was the coil and the other coil worked fine on the "bad" plug).
Similar for my '02 F150 with 208,000 miles on it. Had an original OEM coil go bad a few months ago. Was #7 coil, kind of annoying to get to. Took coil 7 off and replaced it with the coil from #5 (super easy to get to) and ordered 2 cheapie coils off Amazon. Cheap replacement is on cylinder 5 and again, takes 5 minutes to replace if it goes bad. Plugs had been changed 20,000 miles ago and plug 7 looked fine, so did not change it.
On the other hand, had a coil go out on my BMW K1600 motorcycle with 65,000 miles, and that requires several hours to replace, so bought a known good brand replacement coil. Plugs were replaced 5,000 miles ago, and plug on bad coil looked like new. This bike is known to have issues with coils going bad (a lot of heat packed into a small area).
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I'd replace all the plugs, all the boots and springs but only the defective coil. Motorcraft is highly preferred.
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Said engine has all original coils except on 1 cylinder. It failed last summer. Replace 1 at a time.
Hint - old plugs are hard on coils, so if you replace your plugs on time your coils will last longer.
Under the Valve covers @395,000 miles Nissan Xterra VQ40
I finally got around to fixing the very leaky valve cover gaskets on my 395,000 mile Nissan Xterra. I bought this vehicle new in 2008 and I have always ran this on conventional or semi synthetic following approximately the factory recommended 3,750 OCI. Latest few runs have been on Chevron...
bobistheoilguy.com
Hint - old plugs are hard on coils, so if you replace your plugs on time your coils will last longer.
Given the propensity that those coils have for shorting and killing the driver in the PCM in this situation I agree with replacement of all of them. Ford sells a kit still for the 3.5 with 6 plugs, 6 coils and intake gaskets that is reasonable. https://www.tascaparts.com/oem-parts/ford-kit-ba5z12259a
Not with Fords.....I replace more Ford Coils than any other marque combined.
Like Tim said......The Ignitors are built into the ECM where most GM vehicles for example have the Ignitors built into the Coils & have little chance of a bad coil harming the ECM.
Replace them all at once. Why? because I had one go bad on me, filled the catalytic converter w/gasoline, & blew it up. Sounded like all 4 tires blew out going down the road. Black smoke filling the inside of the car. burned the gas line rubber hoses. It was a mess...
REPLACE THEM ALL NOW. It will be cheaper for them to do all now instead of one by one anyways.
REPLACE THEM ALL NOW. It will be cheaper for them to do all now instead of one by one anyways.
I don't know anything about Fords. But on my old RAV4, the OE Denso coil was $100 local. $50 on Amazon. Very easy to change Like <5 minutes easy. Having a pro replace the coils would cost me like $125 x 4 plus labor. Looking at $600 or $700. Doing myself was $50 for one. Wife did drive home on 3 cylinders and triggered the cat converter CEL.
I wouldn't replace them all because one failed. The rest may last the life of the car
Thanks for all the reply. I'm going to try replacing the bad one. All the plugs. And do research on the risk of the cat conv situation.
Thanks again.
Thanks again.
That's good to know.
I would just change the faulty one. Doesn't mean the others are bad or about to fail, I would leave the others alone.. I would make sure the new one is Motorcraft.
I recommend replacing only the bad one. However, as you replace the spark plugs, inspect all of the 'soft parts', i.e. boots, springs, etc. If those are available separately, I'd replace them any time you're changing plugs.
Without knowing how difficult it is to access the coils on your engine, I'd recommend placing the new coil in the most inaccessible location, and moving the others to the locations that are easier to service.
On engines where coil access is difficult, there may be an incentive to change coils even if they are not giving trouble.
As plugs age, the 'demand voltage' increases, which in turn increases the stress on the coil. Regular plug maintenance is key to long coil life.
Without knowing how difficult it is to access the coils on your engine, I'd recommend placing the new coil in the most inaccessible location, and moving the others to the locations that are easier to service.
On engines where coil access is difficult, there may be an incentive to change coils even if they are not giving trouble.
As plugs age, the 'demand voltage' increases, which in turn increases the stress on the coil. Regular plug maintenance is key to long coil life.
Do you know when Ford started doing this?
If the bad coil is in the back, replace all three of the rear coils. If it's one of the front coils, you only need to replace the bad one. Motorcraft is a fair price on Rock Auto.
^ This, replace all in the back if that's where it is, but only if using OE coils, not aftermarket.
However, in almost every case, the driver should notice the rougher running, the dash warning light should come on, and there would be sufficient notice to stop driving it, before enough fuel in the cat caused damage, let alone a fire. Guess the lesson learned is, if the check engine light comes on, pull over and shut it off until you know why. The light is there for a reason and other causes can result in damage too.
That is a very unusual situation, but also one that could happen to many vehicles that have a constant misfire due to the coil failing.
However, in almost every case, the driver should notice the rougher running, the dash warning light should come on, and there would be sufficient notice to stop driving it, before enough fuel in the cat caused damage, let alone a fire. Guess the lesson learned is, if the check engine light comes on, pull over and shut it off until you know why. The light is there for a reason and other causes can result in damage too.
