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Especially for $350, is the benefit really THAT significant? I would like to know what it is.

I guess OEM is ~$100 per, and aftermarket is about $50/per or $300 total, so the price isn't that bad relative to these. But hard to replace all my good ones if not needed
I paid $35.79 each for the Hitachi coils about a year ago.
 

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I paid $35.79 each for the Hitachi coils about a year ago.
^This. With the excellent price per hitachi coil pack at rock auto, currently $32.79, I just feel doing anything different is hard to be justified. This said I get the desire to try to squeeze more mpg out of our rigs but like so many have said who knows if the same effects will be felt with the new oem hitachis. At the end of the day absolutely do what you feel is best for your rig or simply what you’re willing to spend to try something new. For me I’ll just stick with the oem hitachis and only get them from rock auto because of their pricing. Nissanpartsdeal.com has them listed for my 2011 P4X for $105.98 EACH. No thanks lol. Not sure if the oem is actually hitachi or denso but regardless the hitachis are all I have ever put on both of my Xs and they have all (the coil packs) lasted over 100k miles. May be about to do another new set for my ‘06 just for some pm.
 

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So replacing the ignition coils at 70K miles resulted in an increase in throttle response and MPG? Both outcomes indicate better combustion is taking place after coil replacement.

If you google "do ignition coils weaken over time?", you get articles suggesting both Yes and No. Your data suggests the OEM coils with only 70K miles may have weakened over time, or else those new coils are just that much better. I assume the spark plugs weren't changed at the same time as the coils, correct?

After your experiment, I'm tempted to replace my OEM coils with Hitachi coils at 65K on my vehicle just to see if the OEM coils do actually weaken over time. I did an early spark plug replacement at around 60K miles and immediately noticed a smoother idle. If I can extend the life of the CATs even more by preventing more unburnt fuel making its way down to them with fresh coils, it might be an interesting experiment at the RockAuto cost of about 6*32+shipping = $200ish. Hmmmm?
 

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Discussion Starter · #25 ·
So replacing the ignition coils at 70K miles resulted in an increase in throttle response and MPG? Both outcomes indicate better combustion is taking place after coil replacement.

If you google "do ignition coils weaken over time?", you get articles suggesting both Yes and No. Your data suggests the OEM coils with only 70K miles may have weakened over time, or else those new coils are just that much better. I assume the spark plugs weren't changed at the same time as the coils, correct?

After your experiment, I'm tempted to replace my OEM coils with Hitachi coils at 65K on my vehicle just to see if the OEM coils do actually weaken over time. I did an early spark plug replacement at around 60K miles and immediately noticed a smoother idle. If I can extend the life of the CATs even more by preventing more unburnt fuel making its way down to them with fresh coils, it might be an interesting experiment at the RockAuto cost of about 6*32+shipping = $200ish. Hmmmm?
Initially, no I didn't replace the spark plugs, but I still showed increased MPG. I went back in a second time, trying track down a loose connection and at that point, I replace the plugs. The MPG didn't change beyond the initial increase I noticed, though.
 

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The only way to figure this out is with a spreadsheet :p

Someone is going to have to take one for the team. Replace your spark plugs first. Then buy a new set of OEM coils, install them, drive around and record MPGs. Then install a new set of the Audi coils and do the same thing.

Replacing old factory coils with brand new Audi coils and going "These are better than factory coils!" isn't scientific in any stretch.
 

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Initially, no I didn't replace the spark plugs, but I still showed increased MPG. I went back in a second time, trying track down a loose connection and at that point, I replace the plugs. The MPG didn't change beyond the initial increase I noticed, though.
This intuitively makes sense. The hotter coils fattened up the spark in your old spark plugs. Going to new spark plugs didn't make as much difference - because you already had pretty good ignition. At least it sounds good.

I still like the Audi coils. There cheaper, and a lot higher voltage than the Z1 coils. But if you have to lift the manifold to install on 1, then its a bit of a liability. I can swap a OEM coil in the dark without thinking about it. Not that I have ever had to - but sill seems wrong to make something more complex.
 

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Discussion Starter · #28 ·
This intuitively makes sense. The hotter coils fattened up the spark in your old spark plugs. Going to new spark plugs didn't make as much difference - because you already had pretty good ignition. At least it sounds good.

I still like the Audi coils. There cheaper, and a lot higher voltage than the Z1 coils. But if you have to lift the manifold to install on 1, then its a bit of a liability. I can swap a OEM coil in the dark without thinking about it. Not that I have ever had to - but sill seems wrong to make something more complex.
Yeah, getting that front one in is definitely a turn off for a lot of people.
 

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To revive the tread, I have pulled a trigger and purchased the Z1 Performance coils. They should arrive by tomorrow. I will report my findings. My plan is to swap coils only, since the spark plugs in my car are only 32,000 miles young.

June 21 2022 Update:

Coils installed. The car drives fine, but it also drove fine with the OEM coils. I will report MPG changes, if any, once I will accumulate any significant miles.

Jarek
 

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Bratcat,

You might be right with the tune.

Unfortunately,I haven't driven much miles yet to notice any mileage improvement if any (like 50 miles since the install). My car has IMS, CAI, and Magna Flow muffler swap so it drove pretty nice even before the coil swap.
There is a shop two hours away from where I live that does Nissan/Nismo tuning on dyno They are also the UpRev authorized shop.. Last time I have talked to them 3 years ago, they said it would take about $500 to get a tune for the Xterra. It is something on my to do list, maybe later in the year.

Should I disconnect battery to trigger relearn procedure, would that improve anything?

Jarek
 
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