spark plugs

on 3/23/2008 11:58 AM snipped-for-privacy@sympatico.ca said the following:

The 2002 Sentra does not have a distributer, so there are no big cables to follow to the plugs. It has a coil-on-plug (COP) ignition system. The Spark plugs are under the ignition coils for each cylinder. You have to unscrew each coil to get at the spark plug.

willshak wrote in news: snipped-for-privacy@news.supernews.com:

At least you can't mess up the firing order,getting plug wires on the wrong plugs..... ;-)

and you need a long socket extension and a sparkplug socket that doesn't drop the plug or hold on TOO tight to it. My cheapo plug socket holds the plug so tight the entension pops off before the plug,leaving the socket down in the plug well. :-(

innews: snipped-for-privacy@news.supernews.com:

Thanks Jim and Wills. Leo

on 3/23/2008 3:41 PM Jim Yanik said the following:

The CoP system is more efficient than the distributer based system, but if a coil fails, be prepared to spend around $75 for the one coil. I had to replace one on a 2000 Maxima.

It does cost more, but you get:

more power cleaner exhaust much much better reliability from significantly less moving parts that wear out. All you replace are the plugs.

Buh-bye, rotor. Seeya later, cap. I'll put you right there next to the carbuerator in my old car tech museum:)

CD

Hmmm.... $50 worth of rotor, cap, and wires that wears out at 50K miles, vs. four to six $75 coils that typically start to go at 75K miles...

Don't get me wrong, I like direct ignition systems, but for the minor difference in distribution reliability (no cap/rotor) I don't know that it's worth it.

Of course, it's not like we get a choice.

still just me wrote in news: snipped-for-privacy@4ax.com:

where's it say that;"typically start to go at 75K miles"? Or is that just because you had to replace one at around that mileage?

Nothing's perfect, but the direct ignition system, when quality control is on par, is completely maintenance free.

You could go buy a quality aftermarket brand and be completely done with ever touching those coils again.

Of the hundreds of thousands of Altimas out there, ALL cap and rotor equipped Altimas had to have the 50K service . . .every 50 K miles. SO for a car that's destined to go 200K miles at the very least, that's $200 worth of worn out caps, rotors and wires.

For the newer distributorless ones? Just the few who got some bad coils have to replace them once and that's it. $75

CD

Nissan Maxima coils start to go out at that mileage. Some go longer, some a little shorter. Check out Maxmima.org if you like to see how many guys have replaced one or more starting about 60-75k My CA16DOHC, another Nissan I had with direct coils, lost one a about

Likewise Saab direct systems usually go at about 75k, as do Audi. BMW seems to do slightly better but loses some too at high miles. (Not counting the recent Saab and Audi quality issues with some major runs of these parts).

Fair enough. But is it all coils that need to be replaced or just the defective 1 or 2?

CD

A good question. I only had to do one in my CA16. Easy to ID. Many Maxima owners replace all six because they often continue to fail once they start to go (see Maxima.org). But, I got away with one in my Max (Hard to find). There' ve been some massive failures such as the Audi problems - but that was a specific engineering issue where all coils would start to go at 40K. And Saab has a regrettable single unit with

I think the root of the problem is putting moderately sensitive electronic devices on top of an engine - and in most cases, putting a cover on them to make sure they bake. I've yet to see one of these coils with even a simple heat sink.

still just me wrote in news: snipped-for-privacy@4ax.com:

Which was likely a bad manufacturing batch or a poorly designed coil.

COILS are not considered -electronic- devices(electrical,not electronic),and are not "sensitive",even "moderately". "electronics" would be the ECM and the semiconductor circuits that switch the coil primary current.

Problems coils have are bad windings or bad encapsulation/insulation,or improper currents applied to them.(an external problem,not of the coil itself).

I'd agree that a coil of wire is unlikely to go bad unless shorted, etc. FWIW, some do have small switching devices in them.

The bottom line is that there is an unreasonably high failure rate (MHO) on these coils. It's not a strict manufacturing issue when it takes 60K or more miles (or the related time baking) for them to go. Perhaps the bad ones have bad tolerances, but then the manufacturing process has fairly major issues, and across manufacturers. I'd think that it was unlikely so many manufacturers just couldn't get it right

- and it's the design that is just inherently prone to failure from heat and vibration.

still just me wrote in news: snipped-for-privacy@4ax.com:

if the coil was potted properly,vibration should not be a problem. It's possible the potting compound(epoxy) is aging and becoming brittle,and cracking under thermal cycling. I suppose one could create some coil mod where the actual coils are off the motor and a short wire from each coil to the plug,eliminating some of the heat and vibration.

BTW,one Nissan forum I visited cited a Nissan emissions warranty as covering failed coil packs.It seems there's a TSB on it;NTB01-059

It is for 2000-2001 Maximas.