JayQT

I purchased my RX-8 a week ago and I love the car to bits but there are a few things that worry me, so I'm just seeking some advice.

Car Info: 2006 RX-8 Evolve (UK ltd edition), 61k miles, 6 services (5 by mazda dealerships, 1 by subaru).

When starting hot or cold, it takes a few seconds and sounds as if it's struggling and seems like it doesn't want to start. I don't think I've flooded it and I am not losing power at high RPM. I called the dealers where the car was serviced to find out if the coils/plugs have been changed. I was told that the coils have never been changed so I ordered a BHR ignition kit. I'm hoping this solves the starting issue, but I'm wondering if it could be because of something else?

Another problem is when changing from 1st > 2nd and 2nd > 3rd at around 4k RPM the car seems a bit jumpy, not sure if that's because it's lacking power at low RPM or if the mounts are busted or the gears are failing. Also when changing from 3rd > 4th at redline, 4th seems to grind if I shift too fast, no idea what the problem there is.

Any help would be appreciated! Thanks

RIWWP

iTrader: (2)

A) Ignition will assist with starting

B) Another starting issue could be a failing starter. If there is a noticeably longer time starting when hot vs when cold, then add compression failure to the list.

C) 4h gear syncros are traditionally the weakest in our transmission. Rev matching when shifting (up and down) will help save them.

JayQT

Thanks for the reply. I don't notice any difference in the starting time when hot vs cold, but would compression failure mean an engine rebuild is needed? And what do you mean by Rev matching?

EDIT: I forgot to add, I did notice that I'm getting horrible MPG. First tank when I first got the car only gave me 150 miles (city), 2nd gave me around 130 (city) however when I was driving for 3 hours continually (motorway) I got 215 miles. Now I know the RX-8 has poor MPG but I wasn't expecting it to be that low, is there anything that could contribute to this?

RIWWP

iTrader: (2)

A) Compression failure means engine replacement or engine rebuild. However, the first leading sign of compression loss is when hot starts are noticeably longer than cold starts, every time.

B) Rev matching is when you don't shift into a given gear until your RPM is already at the RPM it will be at when you are in the gear with the clutch engaged. 3rd gear in a 6sp MT RX-8 (for example) is at 6,000RPM at 60mph, so if you are in 2nd at 60 MPH (about 8,700rpm), then when shifting up to 3rd, shift out of 2nd, only let the RPMs fall to 6,000rpm, and then shift into gear and then engage the clutch. If you are in 4th at 60mph (about 4,500rpm?) shift out of 4th, pop the revs to 6,000rpm, then shift into 3rd, and then engage the clutch. There are more advanced techniques, but the wider the difference between the RPM of your engine and the RPM of the gear you want at the speed you are going, the harder your syncros have to work. Minimize that difference to save your syncros the work. It's free, smoother on the engine and passengers, minimizes wear, etc...

C) Ignition failure will kill your mileage and your power.

New Owner Thread: https://www.rx8club.com/new-member-forum-197/new-potential-owners-start-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: https://www.rx8club.com/series-i-trouble-shooting-95/impact-old-coils-wires-plugs-234383/ (owner's post here: https://www.rx8club.com/showpost.php...&postcount=189)
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!

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 3 times per revolution, so about 12,000 pulses per minute. That's 10 times more. Even a piston max RPM of about 6,000rpm vs our 9,000rpm makes the difference 3,000 pulses per minute vs 18,000 pulses per minute, or 6 times as fast.

If our coils would last 10 times longer, you are talking an average of 300,000 miles.

So keep your ignition healthy!

JayQT

Again, thanks for the reply.

I don't think it's compression loss (then again, I'm no mechanic). No idea how much my local dealer charges to test, but I'm sure it will be a ridiculous price. The slow start happens when it's cold too. I'm thinking a spark plug is loose or something as I've been doing a bit of research and I noticed a ticking sound coming from the engine too. Some say it's because of the loose spark plugs/wires.

I've uploaded a video to be more clear.

http://youtu.be/qMJ2V2Qv8Fs?hd=1
(warm start, but starts exactly the same when cold)

Hopefully my BHR ignition kit will arrive within the next 2 weeks.

SubliminalPollution

Tilt your phone sideways next time you shoot a video, just a tip.

JayQT

^Yeah, I always forget Damn iPhones.

RIWWP

iTrader: (2)

The starting speed isn't that bad, but it does sound a bit more strained than ideal at the beginning for the crank, so your starter is probably on the low side.

The ticking noise you hear isn't spark plug shorting, it's too "solid" sounding for that. Sounds more like a valve rattle, though it got louder near the driver's side, which is opposite of where the valving is. Not sure of anything else at the moment.

JayQT

^Did you mean the left or right? Not sure if you noticed but I'm from the UK so this is a right hand drive car :o

The reason I said it could be the plugs was because of this video. http://youtu.be/wiI7-iXQj48 Sounded quite similar to me.

RIWWP

iTrader: (2)

My terminology was wrong, but not my intent. The louder sound is plug side, not the valve side. That you happen to drive on the wrong side of the road and sit on the wrong side of the car is just symantics

Well, plugs are easily reached. Just turn the wheel completely to the right and reach in behind the passenger side tire (side with the clicking) Plugs and plug wire ends are right there. The coils are under the intake accordion if you need to check the other end.

JayQT

Been busy so I haven't had much time to do stuff. I did however receive my BHR ignition kit and RP catless midpipe. Installed them both (no CEL :D) and the ticking is still there (most likely the SSV ). My MPG still seems the same to me (12ish avg UK MPG). On the bright side, it starts much quicker than previously (cold and hot, thank god) and seems a lot smoother than before.

Any ideas why the MPG is still very poor?

JayQT

Bump

Bonesy

Jay im in the UK and get about the same MPG, What fuel are you running it on? I get prob 40-50 extra miles to a tank using Tesco Momentum (99octane) but still around 250 to a tank on the M5 staying at 80.Mine also ticks but ive never been able to locate where from.
If you fancy it take the Airbox out and stick your finger in around the Throttle body too see if there is any oil,This could mean theres oil on the SSV

Also i wouldnt bother looking anywhere but here rx8ownersclub are arrogant W*****s and dont help unless you join up the membership

JayQT

Hey Bonesy, thanks for the reply lol.

I've been using shell and esso unleaded, I used v-power on 2 occasions and saw no difference. My MPG did slightly improve to 13ish after changing the ignition system, but still very poor compared to what others are getting.

I'll have a look for oil on the throttle body in a few when this awful rain clears up!

P.s. where in the UK are you from?

Bonesy

I'm in Cornwall mate near Plymouth, i found oil in my TB from over filling the oil. Not by much! Just a tad, Today took my EGR Valve or ACV whatever it is and my christ it was as black as the ace of spades! Hoping when i put it together tomorrow ill notice a difference in mpg :-)

LifeAfterRx8

iTrader: (17)

Sounds to me like an SSV rattle.

Bonesy

I got the SSV out and it was caked in crap.Once i fix the rad ill put it all together and see if i still have the rattle

JayQT

How long did it take you to remove it? I'd try it myself, but knowing me I know something will go wrong in the process

Bonesy

Well it wasn't the easiest job but nothing non this car is! Even changin bulbs means removing wheels

I looked at the video on here and youtube,wrote down everything that was removed in order then got to it.Took 3 hours and 5 Red Bulls to get to the SSV

All i used was 10,12 and 14mm sockets and spanners plus a few screwdrivers and a crowbar to move the EGR pipe to get the SSV out. Im glad i did it as now everything is lovely and clean! As i say the Radiator nipple that the coolant bottle connects to was buggered and botched with a screw but i would leave the coolant bottle on, i just wanted to replace the level sensor. Searching "Remove SSV rx8" will bring the video up on youtube and he links the thread here to it. I also couldn't remoce the ECU/PCM wires or the intake manifold

JayQT

Damn. Still, knowing myself, I would mess something up Did it fix the ticking problem? Also my 8 SOMETIMES, takes longer to start when warm, other times it would start straight away. Still no power loss though, so I'm hoping it's not suffering from low compression (fingers crossed).

Bonesy

Sadly i wont know until i have repaired/replaced the Radiator (prob next week) i will say though that it was completely gunked up in all places it could be,i had trouble getting the ssv out due to this. I too had warm start issues in it taking a little longer but i intend to seafoam as my compression was in the high 7's when i got it tested.

Getting to the SSV is something i wanted to do in case i need to replace it in the future and was a great learning curve with the car.As for power loss,i got it from 4-6k and after that it flew! My mate couldn't lose me in his scooby so i was happy enough lol