Or a term that encompasses both!
Issue with spark plugs
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6th Gear
Joined: Mar 2019
Posts: 13
Likes: 0
From: Florida
Issue with spark plugs
So I went in to get my compensator fixed and the Harley tech told me I had some pre detonation under heavy load(WOT). I just recently replaced all the fluids in my bike so I figured I would go ahead and do spark plugs too so I bought two sparksplugs from them and then came home, I tested WOT and did hear some pings. I switched out the spark plugs and realized that the guy who had my bike before hand had put some NGKs in it and these things still looked pretty decent, but now the pinging is gone with these Harley plugs, so is there anyone who can possibly explain how these, almost new looking spark plugs where causing a pre det when they are the ones that NGK makes for my bike? Im just trying to understand a little more about how this stuff works.
I have a 2010 fat bob.
I have a 2010 fat bob.
Ultimate HDF Member
Joined: Dec 2007
Posts: 9,254
Likes: 283
From: Lake City, Florida (Native)
I do well with OEM Harley Plugs although did do fine with the NGK Iridiums without any problems just wanted to to try them as know a few that swear by them .. Ran them about 5,000 Miles and then switched back to OEM's ..
HDF Community Team
Joined: Aug 2018
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From: New Hampsha
The ECM reads the impedance of the ignition system to detect rapid increases in cylinder pressure, an indicator of preignition and detonation. Some say that other-than-original plugs interfere with the system. I'm not sure how much credence I give to that theory, but your experience would seem to support it.
OTOH, I can't see NGK listing a plug for that engine if it was known to have issues.
OTOH, I can't see NGK listing a plug for that engine if it was known to have issues.
Last edited by John CC; Aug 8, 2019 at 09:39 AM.
HDF Community Team
Joined: Aug 2018
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From: New Hampsha
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Joined: Jan 2007
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From: along the shore of Mishigami
My brother had his bike prepped for a long cross country ride from central FL to upstate New York to west MI and back to Cent. FL. The shop installed the NGK's and a OEM replacement K&N filter. on the way to NY he got the CEL, after he got to MI we checked codes, replaced the plugs with OEM and installed a factory air filter. The CEL never came back on. What's odd is I run the Iridium in my 02 Dyna and 05 Dyna and no problems. It's nuts how this works.
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Ultimate HDF Member
Joined: Dec 2007
Posts: 9,254
Likes: 283
From: Lake City, Florida (Native)
My brother had his bike prepped for a long cross country ride from central FL to upstate New York to west MI and back to Cent. FL. The shop installed the NGK's and a OEM replacement K&N filter. on the way to NY he got the CEL, after he got to MI we checked codes, replaced the plugs with OEM and installed a factory air filter. The CEL never came back on. What's odd is I run the Iridium in my 02 Dyna and 05 Dyna and no problems. It's nuts how this works.
Tourer
Joined: Feb 2016
Posts: 264
Likes: 54
From: .
I run NGKs on my 16, no issues and the ecu knock detection still works. If it pings it will only do it once or twice and the ecu corrects it.
Do you still have the ones you took out? I'd bet they are the wrong heat range or something.
Do you still have the ones you took out? I'd bet they are the wrong heat range or something.