The impact of old coils, wires, & plugs
#1
weeeeeeeeee
Thread Starter
iTrader: (12)
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This weekend I had the honor of hosting an EMS tuning session for a bunch of NE region rotary heads. One of the cars we put on the dyno showed signs of weak coils / plugs.
One of the crew had a spare set of brand new OEM coils, wires, and plugs and we swapped them out and got the 8 back on the dyno to finish up tuning and see what kind of measured improvement we'd get.
The sheet below is from a Series 1 RX-8 with original plugs / wires / coils at a little over 30,000 miles on the odometer.
The "low" numbers are before the swap. The high number is afterwards. While not shown, the car was run a couple times after this sheet to verify the final number. It was not a fluke. The car maintained 199-200 WHP consistently after.
![](https://www.rx8club.com/attachments/series-i-trouble-shooting-95/185882d1339433610-impact-old-coils-wires-plugs-screen-shot-2012-06-11-12.43.29-pm.jpg)
That's right folks... 27 horsepower at the wheels tied up in just coils, wires, and plugs.
Enjoy!
One of the crew had a spare set of brand new OEM coils, wires, and plugs and we swapped them out and got the 8 back on the dyno to finish up tuning and see what kind of measured improvement we'd get.
The sheet below is from a Series 1 RX-8 with original plugs / wires / coils at a little over 30,000 miles on the odometer.
The "low" numbers are before the swap. The high number is afterwards. While not shown, the car was run a couple times after this sheet to verify the final number. It was not a fluke. The car maintained 199-200 WHP consistently after.
![](https://www.rx8club.com/attachments/series-i-trouble-shooting-95/185882d1339433610-impact-old-coils-wires-plugs-screen-shot-2012-06-11-12.43.29-pm.jpg)
That's right folks... 27 horsepower at the wheels tied up in just coils, wires, and plugs.
Enjoy!
#4
FULLY SEMI AUTOMATIC
iTrader: (9)
#11
SARX Legend
iTrader: (46)
Not a surprise if you have ever driven a car with failing ignition coils. The first time my stock coils failed years ago I knew it felt like my car was attached to a huge bungee cord, the higher I revved it, the more sluggish it felt. I replaced them the power was all back again. I think most who don't drive hard don't realize their coils are failing until they start getting a flashing CEL.
#12
Administrator
iTrader: (7)
well done Shell, it's nice to be able to SHOW people that old coils do in fact have a detrimental effect on the car's overall performance.
how many cars did you guys get on the dyno?
how many cars did you guys get on the dyno?
#13
weeeeeeeeee
Thread Starter
iTrader: (12)
Had 7 lined up. One couldn't make it and one had an EFIDude / Mazda ECU model mismatch that prevented him from getting tuned.
And we fit in a Series 2 dyno. Was cool to see its numbers baseline wise compared to the other cars.
And we fit in a Series 2 dyno. Was cool to see its numbers baseline wise compared to the other cars.
#15
Momentum Keeps Me Going
Which were??? Nice info, thanks for that BTW!!
#16
#17
SARX Legend
iTrader: (46)
That's disappointing. Sorry to hear that. These cars can be all over the place I swear. I have seen guys with almost no mods and higher mileage dyno in the 190-200HP range while others with every bolt on possible only hit the 185-190HP range.
#18
FULLY SEMI AUTOMATIC
iTrader: (9)
yep, i thought a s2 with low miles would have done better. my 04 w 75k got 188.64hp with a possible failing fuel pump. best i got on a 55shot before we had to abort because it started to lean out was 213-214
#20
FULLY SEMI AUTOMATIC
iTrader: (9)
another thing some may be interested to know, mine was the only reman engine. it was replaced before i got it at 26k. im at 75k now
#24
Surf Hard, Drive Hard
Join Date: Feb 2007
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This is why my plugs get changed at a maximum of 15k for sure(more like 10k), and the coils every 25k(if I was stock), it's just good insurance.
Thanks for sharing Shell.
Yes, it would have been nice to know if it was plugs or coils....................find it hard to believe it would've been the wires at 30k.
Thanks for sharing Shell.
Yes, it would have been nice to know if it was plugs or coils....................find it hard to believe it would've been the wires at 30k.