OtherSyde

So going on the advice of another member (thanks Dirtyswiff), and because my car was experiencing a rough idle and prolonged turnover periods to start and the engine also seemed have such diminished low-end power/torque that I had to rev it to around 3k to 4k RPM's just to take off without stalling it, I went ahead and bought new NGK Laser Iridium plugs and wires, and BWD/Intermotor ignition coils. I managed to swap them out today without too much hassle.

It looked like the plugs had been changed before because there were already NGK Laser Iridium plugs installed, and they didn't look terrible, although they were definitely dirty:








I don't know anything about rotaries... How bad is that corrosion on the plugs? Was it worth it to change them out or was it a waste of money at this point..?

I think the ignition coils were stock since they looked pretty old/dirty, although it's hard to tell since they don't really have any identifying brand markings on them (but they did look different from the new ones I installed).

As soon as I started up the car I knew it was waaay better, it just purred and hummed with no choking or rough idle, and when I took it out for a test drive in a secluded area I swear it had like 10-20 more horsepower and a way more responsive throttle that showed no sign of wanting to stall at takeoff at all. At a T intersection (with no one else around, on a wide road), I took off into a right turn and punched it, and was immediately surprised as the rear wheels spun out, the rear end of the car swung around as the entire car flung sideways into a power-drift, and then fish-tailed until I wrestled it back into control and straightened it back out. Totally surprised me, because the car could not do that before. Also, I've never driven a rear-wheel drive car before this one (just got it a month ago), so that was one hell of an experience. Gotta say I'm sold on the rotary engine at this point, and all buyer's remorse has disappeared

What I would like to know though, if anyone could tell me, is this: Are these spark plug wires original stock, or have they been upgraded? My car is a 2007 and the wires say "Sumitomo 2006" on them... Did Sumitomo make the stock wires..? Anyone know?



.
Anyways, thought I'd post my n00b adventure for everyone's entertainment... Thanks again to everyone who's given me advice so far!

.

revivo73

I experienced similar improvements when I replaced the IG coils on my 2006 RX-8 last July. The coils were factory fitted and had been used for 7 years. I noticed the torque became more powerful while driving uphill.

Your sumitomo spark cables seem to be factory fitted. I guess that by the date on it, it's 2006 and your car's 2007 so it's likely to be fitted on factory. Which spark cables have you used to replace them, NGK (blue colored ones)?

Your spark plugs seem quite clean. Just compare them to mines:

EviLStewie

Ummmm those plugs looks awesome, barely used.
From what can be seen the plugs aren't causing you any ignition problems.
Actually it doesn't look like you have any ignition issue. Those plugs are clean and the perfect color for a rensis.

So, I'm going to rain on your parade.
New plugs ain't going to give you 20hp it might give you 1-2hp on a dyno up in the high rpm's
Ignition is important no doubt especially at high rpm but I'm sorry those spark plugs you took out look great, still many miles on them unless the porcelain or something is broken on them.

Oh I don't own a 2007 but I don't "think" those are OEM plug wires (guess).

edit:
Oh and in that last picture your hand is entire too clean. You might want to put some grease on it for street cred points.

ken-x8

If the pkugs were OK, the problem was the coils. Those do have a pretty high failure rate as you get close to 40k. Excellent move changing them now.

Does your 8 have traction control? If so, was it off when you had your thrill ride? If I punch mine in a tight corner, traction and/or stability control kicks in and just gives me a vibration.

Ken

OtherSyde

Well ****. It seemed like one of the most popular and common things to do when you get an RX8 that you don't really know the maintenance history of, and with the chugging start-up and rough idle combined with the fact that apparently letting your car continue to misfire and build up carbon not only kills gas mileage but can actually start damaging a Renesis engine in a snowballing kind of way (from what I've read here, correct me if I'm wrong), I figured I'd just go ahead and do it to be on the safe side. I didn't know they'd be so clean. I still have them, should I just keep them for later? Maybe scrape off a little of the buildup on them, if that's even necessary?



Well I mean I figured the plugs weren't going to give me 10-20hp, and if anything it was probably replacing those factory coils and (probably factory) wires that gave any real bump in performance (probably closer to 5 or 6 hp total right?) - really only bringing the car back up closer to original factory performance rather than anything else I guess. It definitely runs better though, for sure.



Haha I deliberately kept my hands clean by washing them off with the garden hose so that I could continue my text conversation with this girl I met on Plenty Of Fish without getting my white phone covered in grease lol



Hmmm. No idea, but it would have to have been off at the very least for this to happen, right..? I dunno. I've had a '98 Contour SVT for a decade, so I've never experienced traction control... Or anti-lock brakes either, for that matter (the system was busted from the get-go in that old beast lol).

Also, I did replace the wires with NGK Blue wires... Is that bad? Unfortunately, I can't afford the much-better BHR kit right now

Anyway I'm still happy I did this maintenance, even if the plugs really didn't need changing; if nothing else it give me a little peace of mind and will prolong the engine life a bit.


Next up I guess I need to do the grounding wire upgrade/replacement thing, because my 1,500watt amp dims the headlights constantly and I read on here that a farad cap apparently does nothing for that
_
_

BigCajun

iTrader: (1)

Welcome, Imo, plugs are not worth keeping. Never go cheap on this car. Proper maintenance is critical. Plugs coils & wires every 30k.
Blue wires are fine, I put a new set on in March, DD mostly every day.
Traction control can't override physics, if you take a corner too fast, you'll slide. If it was on, the light on the dash should have lit up briefly when you slid.
If you're not used to RWD, next time it rains, go find an empty parking lot & practice skid steering.
Read the new owner stickies!!!!!!
Have fun!

OtherSyde

Thanks, now I feel better about having replaced them.


OK will do!

RIWWP

iTrader: (2)

Replacing them at 35k is acceptable, but yes, your plugs look fairly good, better than they should at 35k, so the prior owner probably did replace plugs early. Considering the improvement made, it sounds typical of something in the ignition failing that you covered, so gratz on doing proper maintenance before cascading failures really start to cause problems.


Here is a point on the power you can restore (not gain) from healthy ignition, from the New Owner's thread: https://www.rx8club.com/new-member-f...t-here-202454/
Importance of Ignition Health:
************************ READ THIS!!!! ************************

One of the most often overlooked or ignored parts of RX-8 ownership is the health of the ignition system. This includes the ignition coils, spark plug wires, and spark plugs. They fail. Often. So often as to be critical parts of regular maintenance.

Before I detail why, check out the first post of this thread here: The impact of old coils, wires, & plugs - RX8Club.com (owner's post here: [FEELER] Spring 2012 MM Tuning / Dyno Day @ Speed1 Allentown (formerly KDRotary) - Page 8 - RX8Club.com)
The owner's power dropped from 199whp to 172whp JUST from failing ignition. That's a 13.5% power loss!

Do I have your attention now? Good.

Mazda officially lists the plug wires and plugs as part of regular maintenance, but not the coils. Many dealers STILL don't know how easily the coils can fail. And they fail about the same time as the wires and plugs, which is about every 30,000 miles. Some can last longer, some shorter, and it's more related to your total RPMs than it is to your mileage. Highway cruising is easier on the coils than spending a day pounding around a race track.

When coils fail, they don't suddenly shut off. They start producing weaker pulses scattered among strong ones. The rate of weak pulses slowly increases and pulses start getting dropped entirely, which is where misfires start. All of this means that you aren't burning all the fuel and aren't using all the air that the engine pulled in for that combustion, and it unburnt fuel and air gets dumped into the exhaust, where it happily ignites with the presence of plenty of heat. This saturates the cat in both fuel and heat, and will rapidly kill the cat (A $1,300 USD replacement). Continuing to drive on a failing cat will add other problems such as engine damage and vehicle fires. I am not exaggerating, this can happen with just a single cat failure!
Example: RX8 Engine responce HELP! - RX8Club.com

Plug fouling and wire failure is largely the same result, since all 3 pieces are needed for a complete spark. Foul the plug and it doesn't matter if the coil and wire are good. Break down the wire and it doesn't matter if the coil and plug are good.


Symptoms of ignition failure include: Power Loss, mileage drop, unstable idle, bad idle, inability to idle, shaking at idle, unstable high rpm, misfiring, flashing CEL, coughing engine, glowing cat, flooding, inability to start, inability to pass an emissions sniffer test, and just about anything you can think of where a weak or missing spark causes problems.

And if one fails, it will cascade to the other trio on the same rotor. A plug that can't fire will start fouling the other. A coil that can't fire a plug starts wearing out rapidly (if you want to test this, just unplug a wire from a plug and run the engine for a while. The coil will rapidly fail. Not unique to rotary engines)

Why do coils fail so easily?

This is largely because Mazda opted for cheap coils because of RX-7 owner complaints about how expensive their coils were. The RX-7 coils lasted much longer though. So Mazda went cheap, and so we have to replace regularly. And you can't compare to piston engine coils. A piston engine with the same setup of 1 coil for 1 plug has an average RPM of about 2,500rpm and the coil is firing every other revolution, so the coil is firing about 1,250 pulses per minute. Our rotary has an average RPM of more like 4,000rpm, and each coil fires every revolution, so about 4,000 pulses per minute. That's a bit over 3 times more. Even a piston max RPM of about 6,000rpm vs our 9,000rpm makes the difference 3,000 pulses per minute vs 9,000 pulses per minute, or 3 times as fast.

If our coils would last about 3 times longer, you are talking an average of 90,000 miles.

So keep your ignition healthy!

OtherSyde

Nice, yeah that's part of what prompted me to swap them out. Thanks for not ripping on the new guy.