Question about ignition leads
10-06-2012, 07:55 AM
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Question about ignition leads
Hi everyone, iv been told I need new leads and plugs, this may sound like a really stupid question but... Are ignition/ ht/ coil leads all the same thing just different terminology ?
Sorry if that's an obvious answer lol
Sorry if that's an obvious answer lol
10-06-2012, 08:13 AM
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Leads is the more common term used in Europe for what we call plug wires here in the US.
If you need new plug wires and plugs, then you probably also need new coils. They all tend to fail around the same time, though most shops don't recognize that the coils will fail, and will keep assuming it's the wires and plugs. You can replace all 12 pieces (4 coils, 4 wires, 4 plugs) in about an hour with a plug socket, a 10mm socket, a ratchet, and some extensions. Nothing else required, and you can replace them all quite a bit faster if you know your way around the car and are handy with tools. 1hr if you don't know what you are doing.
I am not sure what prices you see over in the UK, but you will want to do some shopping around for the best prices. Recent posts from people in the UK regarding ignition parts prices at Mazda dealers has the coils at 30-50 quid each, plugs for 25 quid each. You can usually find the parts for at least 1/2 of the dealer price, if not 1/3rd. Most auto parts stores here in the US carry the OEM parts, so you should be able to find them in the UK as well.
https://www.rx8club.com/rx-8-discuss...t-here-202454/
If you need new plug wires and plugs, then you probably also need new coils. They all tend to fail around the same time, though most shops don't recognize that the coils will fail, and will keep assuming it's the wires and plugs. You can replace all 12 pieces (4 coils, 4 wires, 4 plugs) in about an hour with a plug socket, a 10mm socket, a ratchet, and some extensions. Nothing else required, and you can replace them all quite a bit faster if you know your way around the car and are handy with tools. 1hr if you don't know what you are doing.
I am not sure what prices you see over in the UK, but you will want to do some shopping around for the best prices. Recent posts from people in the UK regarding ignition parts prices at Mazda dealers has the coils at 30-50 quid each, plugs for 25 quid each. You can usually find the parts for at least 1/2 of the dealer price, if not 1/3rd. Most auto parts stores here in the US carry the OEM parts, so you should be able to find them in the UK as well.
https://www.rx8club.com/rx-8-discuss...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: 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 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!
************************ 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 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!
10-06-2012, 10:51 AM
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That's a much better response lol yeah I do need all 3 iv bought coils and plugs but was just unsure about the leads, which to buy? Is it worth payin extra for magnecor leads or will the cheaper ones do?
Cheers for help
Cheers for help
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