Ignition Coils... Wear item? When to replace?

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Back when these COP ignition systems first came out, all the old timers were complaining how instead of replacing just one coil, they would have to spend up to 8 times as much now to replace them on a V8. They forgot that if a coil goes out on an older car, you're stuck by the side of the road. If a coil goes bad now, at least you can still get home.
 
Originally Posted by dishdude
Originally Posted by atikovi
Kinda like the question posted once before asking if they should replace their 200,000 mile radiator, headlights or struts. You can, but why waste money on it if you don't need to. Bad coils are readily apparent from misfire codes and basic diagnosis when they do go bad.
Exactly. You can make this case for countless parts on the car, the only solution is to replace all of them...with a new car!

There's a guy on YouTube that shows his mods and repairs on his car (a G35). He replaced his alternator as "preventative maintenance" ! Current alternator was showing no signs whatsoever of issue.

People that replace items like this will justify it to no end with the argument that it will save them from being stranded on the road one day.
 
Originally Posted by hallstevenson
Originally Posted by dishdude
Originally Posted by atikovi
Kinda like the question posted once before asking if they should replace their 200,000 mile radiator, headlights or struts. You can, but why waste money on it if you don't need to. Bad coils are readily apparent from misfire codes and basic diagnosis when they do go bad.
Exactly. You can make this case for countless parts on the car, the only solution is to replace all of them...with a new car!

There's a guy on YouTube that shows his mods and repairs on his car (a G35). He replaced his alternator as "preventative maintenance" ! Current alternator was showing no signs whatsoever of issue.

People that replace items like this will justify it to no end with the argument that it will save them from being stranded on the road one day.

Struts and radiators are wear items.
When I got my Tundra, the original shocks were squishy as heck. A set of Bilsteins did the trick.
I want to R&R the radiator, as the transmission fluid flows through it as well as coolant. I had the dreaded strawberry milkshake on an Accord; its radiator seemed fine.
While the Tundra's radiator seems to be fine, a new Denso would give me peace of mind and just might save a transmission nightmare.

Just my 2 cents.
 
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How do you account for, or guess is, the cause of breakage?

1) Old tech material failure like early "rubber" compounds. Things dry out, embrittle and arc.

2) Flawed material e.g. imperfect wire or connection point? Weak point burn out, failure to conduct electricity etc.

3) Control electronics? Sure, it's gotten better since the '50's (dawn of Fuel Injection) but still fail occasionally.
Since consumer products have "infant mortality" or last a long, long time, what constitutes "infant mortality" in the production and QC of coils?

As reported here: I contacted a big Volvo parts source regarding the separate coils (COP's, not a pack or cassette) used in Volvo 5 cylinder engines ca. 1983-2009.
The seller said he stocked them and has never sold one.
 
Both the Mustang and XTerra developed coil-related misfires, and instead of just replacing one, I replaced them all. If one goes out, I figure the others can't be far behind considering they are constantly exposed to what is probably the hottest part of the engine, but I would not replace them at a set mileage just as preventative maintenance.
 
Something like the Corolla where you can get to them without drama, replace on failure.

Something more difficult like my daughter's V6 Escape or some 4 cylinder Nissans where the intake manifold has to come off, upon first failure, I replace all the coils under the manifold.

So in the case of my daughter's car, we did 3 of the 6 since the other 3 were unobstructed by the IM.

Since good coils can be $50-$100 each, I don't go for prophylactic replacement unless it's a chore to get to them as in they are buried under other components.

Originally Posted by JeffKeryk
We see more and more posts about replacing ignition coils.
I recently replaced a bad coil on a friend's 2009 Corolla; thanks to the great feedback from this forum I saved some bucks on the brand.

I have 2 vehicles approaching 200K miles; wifey's beloved 2006 TSX and my trusty 2001 V8 Tundra.
Does it make sense to R&R the original coils?
Remember gas is pretty expensive in sunny Silicon Valley...

I appreciate your thoughts.
 
I keep an eye on low mileage junkyard cars if they have a website & buy a couple. Came in handy on a sidejob more than twice
 
Originally Posted by Kira

3) Control electronics? Sure, it's gotten better since the '50's (dawn of Fuel Injection) but still fail occasionally.
Since consumer products have "infant mortality" or last a long, long time, what constitutes "infant mortality" in the production and QC of coils?

As reported here: I contacted a big Volvo parts source regarding the separate coils (COP's, not a pack or cassette) used in Volvo 5 cylinder engines ca. 1983-2009.
The seller said he stocked them and has never sold one.



I had to replace all four coils on a co-worker's Fit and it looks like they are a fact of life on those engines. Modern direct ignition coils are made with better materials but the coils are smaller with denser windings and incorporate the triggering circuit(an igniter in Toyota/Honda speak) which is basically a transistor that switches the coil on and off from the PCM.

The triggering circuit doesn't really fail too often but the windings or the boots do. Not sure about non-Toyotas, but Toyota uses a IGF signal from the igniter to confirm if the coil fired, no IGF means no spark which will set a DTC. It's supposed to be a fail-safe in the event of a misfire to prevent cat damage. Didn't help me, but the car it happened on used batch-fire EFI and the engine used two distributors, two coils and two igniters for a V8.
 
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