Spark plug electrode broke off
#1
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Spark plug electrode broke off
I went to do compression testing on the car and removed the trailing plugs and they looked fine. I then removed the leading plugs to check their condition and notice the side electrode has been broken off and gone, on both leading plugs. The plugs has one season of track use and some street miles, probably 2k miles total. I asked my other two friends that also track rx8 and they said they had that happened before also and thought they were the only one. Is this a common thing or just a bad batch of NGK. this must have happened awhile ago because i've been trying figure out why the car was getting misfire since last year. but never thought to check the spark plugs since they were new. ive done compression test before but only pulled the trailing plugs and never checked the leading one.
Here's picture of the broken one.
Here's picture of an older plug from my old engine with 75k miles. The electrode is still attached.
Here's picture of the broken one.
Here's picture of an older plug from my old engine with 75k miles. The electrode is still attached.
Last edited by trackjunkie; 09-03-2019 at 07:54 AM.
#2
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As long as it didn't make its way into the engine you should be ok.
#4
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#5
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the plug with the electrode still on it is from another engine. not from the engine that's in my car. i just posted the picture for comparison. both leading plugs from the engine in my car is missing electrode
#7
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#9
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Did you install the plugs. If not it makes me wonder if the previous owner put them in like that.
#10
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yeah electrode missing on both leading plugs. i check with two other track buddies with rx8 and they said they have had same thing happened.
#11
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#12
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didn't see any knock when i was logging on the dyno. unfortunately i don't have a way to log knock while on track. i'm running e85 and pretty much stock timing
#14
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i'm using standard 7 heat range. never really thought of using colder plug since im not running FI. but i guess things does get pretty hot when running constant WOT. where did you get colder plugs? i did a quick google search and was only able to fine RE8C-L on amazon. did not find any 9 or 10 range. the search on mazdamotorsport is useless.
also RE7C-L are $29 on motorsport but only $20 at advance auto. dafug
EDIT:
i found RE6C-L on motosport but no 8/9/10
also RE7C-L are $29 on motorsport but only $20 at advance auto. dafug
EDIT:
i found RE6C-L on motosport but no 8/9/10
Last edited by trackjunkie; 09-04-2019 at 07:14 AM.
#15
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So what exactly does a colder plug do? And is it worth it for very hard street driving. I kinda treat the street like a track most of the time. Shhhhh
#16
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colder plugs dissipate heat quicker and keeps the center electrode cooler, reducing chance of pre-ignition. but also not great for cold start in colder climate.
#17
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the Renesis-specific NGK R7440A- L / R7440B- T iridium racing plug is preferred but expensive, there are also aftermarket plugs like Denso etc and the NGK 13B R6725 / R7420 racing plug can also be used.
https://www.rx8club.com/series-i-maj...thread-253547/
I wondered if this also was playing into your cutout issue. If you have good spark and crank rpm they should light off fine. The only time I ever had slow starts was from a lowish battery in cold weather. I never had a single Renesis flood, not even in 20 deg F weather with E fuel.
not really interested in addressing street car stuff, my comments are specifically for TJ.
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https://www.rx8club.com/series-i-maj...thread-253547/
I wondered if this also was playing into your cutout issue. If you have good spark and crank rpm they should light off fine. The only time I ever had slow starts was from a lowish battery in cold weather. I never had a single Renesis flood, not even in 20 deg F weather with E fuel.
not really interested in addressing street car stuff, my comments are specifically for TJ.
.
.
Last edited by TeamRX8; 09-04-2019 at 09:02 AM.
#19
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so it looks like the cheapest place is direct from NGK. 9 for leading and 11 for trailing. is it important to have two heat range step between leading and trailing like oem? or run 9-L and 10-T
https://www.ngk.com/product.aspx?zpid=10138
https://www.ngk.com/product.aspx?zpid=10140
https://www.ngk.com/product.aspx?zpid=10138
https://www.ngk.com/product.aspx?zpid=10140
#22
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I saw you had asked about dwell a while back. I did end up dropping those numbers down some over concern for quality variance on the D585 coil and its tendency to have sporadic auto-discharge at high dwell. That’s my main reason for switching to the IGN-1A. Which I always knew was the coil to be using.
#23
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yeah i saw your response to that thread. i have removed the LS setup when one of the coils died while i was at the track few months ago. luckily i brought the oem setup in my spare parts box and was able to continue racing. i think i'll just stick with oem coils for now and just replace often and keep spares around. also didn't want to mess around guessing the dwell settings.
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