Ignition and cat trouble
09-05-2012, 04:52 AM
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Ignition and cat trouble
Good Morning to all the techies out there from a completely non tech retired accountant.
I have a 2003 Mazda RX 8 . Great to drive but so unreliable that I want to sell it. I have had it since new- regular service by main dealer and only 38000 miles on clock
I have had regular problems with engine flooding and was getting less than 18mpg .
It looks like best price would be about £2300.
Last week however the car barely moved when I pressed acceelarator.
Recovery mechanic said that it is a multi function breakdown.
Garage of main dealer have phoned to say that al 4 ignition coils need replacing at a cost of £400+ - but that they could not guarantee that the catalyst had not been damaged and that might need replacing at £1500+.
Given that it also need 2 new tyres and with a oil leak from gear box reverse switch etc I ask for advice.
Is it worth risking the cost of replacing the ignition coils in tghe hope that catalyst is ok or should I just scrap the thing and cut my losses
It seems
I have a 2003 Mazda RX 8 . Great to drive but so unreliable that I want to sell it. I have had it since new- regular service by main dealer and only 38000 miles on clock
I have had regular problems with engine flooding and was getting less than 18mpg .
It looks like best price would be about £2300.
Last week however the car barely moved when I pressed acceelarator.
Recovery mechanic said that it is a multi function breakdown.
Garage of main dealer have phoned to say that al 4 ignition coils need replacing at a cost of £400+ - but that they could not guarantee that the catalyst had not been damaged and that might need replacing at £1500+.
Given that it also need 2 new tyres and with a oil leak from gear box reverse switch etc I ask for advice.
Is it worth risking the cost of replacing the ignition coils in tghe hope that catalyst is ok or should I just scrap the thing and cut my losses
It seems
09-05-2012, 12:10 PM
#2
buy the coils plugs and wires not from the dealer, and swap them out yourself. It took me an hour and it was my first time.
Im not sure how much it is where you live, but i got a set from Mazmart for $311.
just buy a midpipe if you dont have emissions.
Im not sure how much it is where you live, but i got a set from Mazmart for $311.
just buy a midpipe if you dont have emissions.
09-05-2012, 12:35 PM
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Sounds like the root of your problems is failing ignition, which is from neglecting to replace them as needed. Intentional or not, justified or not, our ignition needs regular replacement and failing to do so leads to cascading problems.
From my new owner's thread: https://www.rx8club.com/rx-8-discuss...t-here-202454/
From my new owner's thread: 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: 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!
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: 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!
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!
09-05-2012, 03:41 PM
#4
Rockie Mountain Newbie
Good Morning to all the techies out there from a completely non tech retired accountant.
I have a 2003 Mazda RX 8 . Great to drive but so unreliable that I want to sell it. I have had it since new- regular service by main dealer and only 38000 miles on clock
I have had regular problems with engine flooding and was getting less than 18mpg .
It looks like best price would be about £2300.
Last week however the car barely moved when I pressed acceelarator.
Recovery mechanic said that it is a multi function breakdown.
Garage of main dealer have phoned to say that all 4 ignition coils need replacing at a cost of £400+ - but that they could not guarantee that the catalyst had not been damaged and that might need replacing at £1500+.
Given that it also need 2 new tyres and with a oil leak from gear box reverse switch etc I ask for advice.
Is it worth risking the cost of replacing the ignition coils in the hope that catalyst is OK or should I just scrap the thing and cut my losses?
I have a 2003 Mazda RX 8 . Great to drive but so unreliable that I want to sell it. I have had it since new- regular service by main dealer and only 38000 miles on clock
I have had regular problems with engine flooding and was getting less than 18mpg .
It looks like best price would be about £2300.
Last week however the car barely moved when I pressed acceelarator.
Recovery mechanic said that it is a multi function breakdown.
Garage of main dealer have phoned to say that all 4 ignition coils need replacing at a cost of £400+ - but that they could not guarantee that the catalyst had not been damaged and that might need replacing at £1500+.
Given that it also need 2 new tyres and with a oil leak from gear box reverse switch etc I ask for advice.
Is it worth risking the cost of replacing the ignition coils in the hope that catalyst is OK or should I just scrap the thing and cut my losses?
You say your car is worth £2300.
If you add in £1900 more for the coils and the convertor, that brings your car up to £4200. Add in a bit more for tyres and replacing the leaking switch. Lets say £4600, just for a nice round figure.
Now, go look for a car that drives as well as the RX-8 for that same £4600.
What do you find out in your market? If you see something you like, sell your car, and go buy it. If you don't see anything you like, then have the compression tested, to see how much longer your engine should last with having a faulty ignition system killing the motor and convertor for so many years.
If your engine shows healthy, replace all the bits, and continue driving, if not, then you have to decide if you want to replace all the bits, and the engine at quite a bit more money, and go from there.
BC.
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