Ignition Coil Lifespan

[June]

I thought these CPs were known to have a predictable drop in spark intensity as they age. Or is that 'marketing' circulated by retailers trying to sell you something you don't need?

Pure bunk! A ignition coil is basically a transformer, put X voltage in and as long as the windings are intact and not open electrically the voltage out will always be the same. I understand as the plug gap increases the draw of power increases until the windings open like a burnt fuse. June

[mrbrian200]

Yes they get unfiltered +B through a relay from the engine bay fuse panel. You'd have to step up the supply voltage or adjust the dwell. 5 minutes or less on google: modern ECUs adjust the dwell time from a table with battery voltage as a variable, and aftermarket tuning software can modify this table on Volvos.

I'm with ya June: in a perfect world these shouldn't really ever degrade. I'm willing to entertain that these miniaturized coils may have certain susceptibilities to degradation compared to older larger ignition coils from the 'distributor' era. In addition to the magnet wire needing to be an insanely small gauge to get the number of turns necessary to generate high voltage, the wire insulator would also need to be exceptionally thin. I could imagine the insulator starts to degrade and shorts start to pile up between adjacent loops of wire.

I have no evidence to support this starts to happen in the span of 10y/100k miles. Unless someone from Bosch R&D were to pop by and confirm that these coils lose their output over time and why, the previous paragraph would be nothing more than a conspiracy theory lacking a ridiculous youtube video.

[abscate]

Unlike the single coil system the packs sit on top of a hot cylinder head cover bathed in leaking PCV OIL

I’m surprised they last 100k

[precopster]

When the exterior casing cracks they misfire. If you peel back the rubber boot you can thoroughly inspect the casing and check for this, otherwise they last a long, long time. You can do this at every spark plug change as routine maintenance.

I have purchased aftermarket boots from AC Delco for $15 and eliminated misfires on more than one occasion.

I've only had one fail with no visible cracks out of around 70 of them.

[cn90]

- For my BMW and Volvo, I buy about 2-3 used (but Genuine) coils from ebay with good boots.

- It is about $10-$15 each.

- Then I keep these used coils in the trunk and forget about it. It is an inexpensive way to deal with issue. Never know you are hundreds of miles from home and need a coil, which is an easy fix with simple tool.

- BTW, I removed the cosmetic plastic cover and left it on the garage shelf at home, this gives me direct access to the coils.

[abscate]

100 uses for the Volvo cosmetic cover...

Tray for coffee

Emergency snow shovel

Door ornament

1/2 of a set of snow shoes, predrilled to take your boot laces

Neck brace ( the front part with the nice curved part)

Play ramp for gerbils riding very small bikes

......

[Rattnalle]

Depending on where you drive it actually keeps quite a lot of debris out of the area around the coils. My car is a mess under the hood

[RickG]

When a coil is failing, does it trigger a check engine light and log which cylinder? Two folks I know are dealing with intermittent misfiring issues on their high mileage V70s. They shop has indicated this is 99% due to ignition coils but there's no way to determine which coil is going bad until it fails. So how does one proactively determine which coil to swap while the car periodically runs rough (but is not triggering the Check Engine light)? Thanks -

[Rattnalle]

When a coil is failing, does it trigger a check engine light and log which cylinder? Two folks I know are dealing with intermittent misfiring issues on their high mileage V70s. They shop has indicated this is 99% due to ignition coils but there's no way to determine which coil is going bad until it fails. So how does one proactively determine which coil to swap while the car periodically runs rough (but is not triggering the Check Engine light)? Thanks -

If the engine detects misfires it will store a cylinder specific code if its bad enough.

The other way is to get a spare and switch them around until it goes away when you find the right one.

[abscate]

When a coil is failing, does it trigger a check engine light and log which cylinder? Two folks I know are dealing with intermittent misfiring issues on their high mileage V70s. They shop has indicated this is 99% due to ignition coils but there's no way to determine which coil is going bad until it fails. So how does one proactively determine which coil to swap while the car periodically runs rough (but is not triggering the Check Engine light)? Thanks -

Rick...you can’t depend in the code P030x , where x is the cylinder that is misfiring , to guide you on an intermittent miss.

My guidance would be...

Buy two new Bosch or Volvo could from your favorite vendor

Replace cylinder 1,2 . Drive. Move to 3,4 if miss returns. Drive. Replace 5 if miss returns.

If steps 1,2 cure it, isolate bad cylinder by swapping.

You can buy the torx screw and 10mm socket for 10% of what The $150 the shop will charge you for coil plus labour.

Keep second as spare for next failure.

Make sure they are using the right plugs too, three prong for NA, single prong for turbo. Replace every 30-60k depending on tip type.