DIY: How to replace ignition coils
05-06-2009, 06:33 PM
#30
I think this is a valid question, especially after I had an admitted inexperienced mechanic work on my ignition system last week at the dealership. Three coils dead, so he's swapping the connectors and leads about to find the one good coil / verify the dead bodies. I can't be sure he got the right connectors to the right coils, and I've yet to find a decent wiring diagram with the color codes for the leads.
Before I kill this poor car from detonation, what is the code?
EDIT: Wouldn't you know, Mugatu was right? TeamRX8 dropped the clue in 2006. 'Thanks!
Last edited by Striker-7; 05-06-2009 at 06:53 PM.
05-18-2009, 05:26 PM
#31
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Well after following the DIY write up on replacing the ignition coils, I finally completed mine. 
Thanks to Mazurfer for the write-up. 
Besides putting in new ignition coils, I also replaced the stock plug wires with a set of Moroso wires. Also replaced the stock battery with an Optima Red Top.
On a scary note though while I was securing the negative clamp on the battery, my wrench slipped and hit the positve pole of the battery. BZZZZZT!!!
Scared the bejeezus out of me. Checked my car, turned on the keys.... looks like nothing shorted on any of the car's electronics. After finishing all my installations, I drove my car around for about 20 miles, driving casually and sometimes redlining the hell out of it. Looks like all is good. But still, those sparks still scared the 
out of me.
Thanks to Mazurfer for the write-up. Besides putting in new ignition coils, I also replaced the stock plug wires with a set of Moroso wires. Also replaced the stock battery with an Optima Red Top.
On a scary note though while I was securing the negative clamp on the battery, my wrench slipped and hit the positve pole of the battery. BZZZZZT!!!
Scared the bejeezus out of me. Checked my car, turned on the keys.... looks like nothing shorted on any of the car's electronics. After finishing all my installations, I drove my car around for about 20 miles, driving casually and sometimes redlining the hell out of it. Looks like all is good. But still, those sparks still scared the out of me.
05-23-2009, 10:49 AM
#33
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Do you think you over tightened it or do you think the bolt was defective? What were you using to tighten the bolt? Can you get a pair of locking pliers on it and turn it out, then put in a replacement bolt? Pictures?
05-23-2009, 02:16 PM
#34
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Thanks for the reply
Luckily after 5 hours and 1 angle grinder its ok.
Had to get the ignition plate out (not easy i can tell you!!) then angle grind the old bolt off and replace with a new one.
Thats the 3rd bolt ive snapped using just a socket wrench and my bare hand since i got my 8, maybe japanese parts arnt quite as good as i thought!!
Luckily after 5 hours and 1 angle grinder its ok.
Had to get the ignition plate out (not easy i can tell you!!) then angle grind the old bolt off and replace with a new one.
Thats the 3rd bolt ive snapped using just a socket wrench and my bare hand since i got my 8, maybe japanese parts arnt quite as good as i thought!!
06-22-2009, 04:44 PM
#35
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I would like to thank the contributors of this thread! It save me lots of money by not going to the dealer.
I did do it a bit differently since I have skinny arms and was able to replace the wires at the same time with out removing anything else or jacking up the car.
Tools used:
10mm socket
Rachet with 3 inch extension
I did do it a bit differently since I have skinny arms and was able to replace the wires at the same time with out removing anything else or jacking up the car.
Tools used:
10mm socket
Rachet with 3 inch extension
12-05-2009, 07:25 AM
#36
Just a quick (hopefully) note. I had the problem several others have mentioned here, car started running like a tractor, smelling so bad I had to open all the windows, barely made it home and noticed that the CAT was glowing red hot. From what I read here, I figured BAD COILS. I changed coils and plugs just to be safe and the car runs great now. Here's the kicker. Advance Auto was the only local parts store that could get the coils for me because they said Mazda discontinued them due to having so much trouble with defective coils. So, the 21 dollar coils ended up costing me 78 dollars each. WTF!
12-05-2009, 11:41 AM
#37
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Advance Auto was the only local parts store that could get the coils for me because they said Mazda discontinued them due to having so much trouble with defective coils
You can buy them on line for $30 each from Mazda Dealers, or in some cases even cheaper.
# N3H1-18-100B9U
09-10-2010, 12:35 PM
#38
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Help
Thanks for the reply
Luckily after 5 hours and 1 angle grinder its ok.
Had to get the ignition plate out (not easy i can tell you!!) then angle grind the old bolt off and replace with a new one.
Thats the 3rd bolt ive snapped using just a socket wrench and my bare hand since i got my 8, maybe japanese parts arnt quite as good as i thought!!
Luckily after 5 hours and 1 angle grinder its ok.
Had to get the ignition plate out (not easy i can tell you!!) then angle grind the old bolt off and replace with a new one.
Thats the 3rd bolt ive snapped using just a socket wrench and my bare hand since i got my 8, maybe japanese parts arnt quite as good as i thought!!
I know this thread is kind of old, but i just did the same thing and I was wondering if someone could explain how to get the plate out.
09-10-2010, 01:00 PM
#39
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09-14-2010, 10:53 AM
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No offense, and mine isn't going to be worded well as im going to rush this but that guide to removing coils is way too involved. I try to avoid pulling the airbox at all costs as it is a pain in the ***, also there's no reason to disconnect the battery, while a "standard procedure" for electrical work it's not really necessary.
All you really need is to remove the 10mm hose clamp on the square plastic box to the right of the TB, unclip the small plastic hose attached to it. Then remove the black box.
You'll be able to see the coils rather clearly. There is a clip for the harness attached to the coil mounting plate, with a firm one hand push downward it will bend out of the way of the first coil's nut making all 4 easily accessible.
Now remove the spark plug wires from the coils, easiest way to do this is (standing over the fender) rock them towards the front and back of the car, then with your hand on the boot using one finger grab the lip of the boot and try peeling it up while lifting the boot, this is to break the seal between the rubber and the coil (due to the heat they become semi bonded)
After that use a 1/4" ratchet with a decent size extension (i use an extension that reaches over the hoodline so i dont have to lean over at all, im just lazy) also a 1/4" swivel adapter and 10mm deep socket. May want to have a magnet handy to grab the 4 nuts when you remove them.
Now with the nuts removed you should be able to pivot the bolt hole portion of the coil up and over the stud, there will be enough slack in the wiring to pull it slightly towards you and make disconnecting the connector easier.
To reassemble proceed in reverse order.
Thats how i do it daily, makes changing all 4 coils about a 5-10 minute affair.
also remember the coils, from firewall forward, are t2,l2,t1,l1.
kevin.
All you really need is to remove the 10mm hose clamp on the square plastic box to the right of the TB, unclip the small plastic hose attached to it. Then remove the black box.
You'll be able to see the coils rather clearly. There is a clip for the harness attached to the coil mounting plate, with a firm one hand push downward it will bend out of the way of the first coil's nut making all 4 easily accessible.
Now remove the spark plug wires from the coils, easiest way to do this is (standing over the fender) rock them towards the front and back of the car, then with your hand on the boot using one finger grab the lip of the boot and try peeling it up while lifting the boot, this is to break the seal between the rubber and the coil (due to the heat they become semi bonded)
After that use a 1/4" ratchet with a decent size extension (i use an extension that reaches over the hoodline so i dont have to lean over at all, im just lazy) also a 1/4" swivel adapter and 10mm deep socket. May want to have a magnet handy to grab the 4 nuts when you remove them.
Now with the nuts removed you should be able to pivot the bolt hole portion of the coil up and over the stud, there will be enough slack in the wiring to pull it slightly towards you and make disconnecting the connector easier.
To reassemble proceed in reverse order.
Thats how i do it daily, makes changing all 4 coils about a 5-10 minute affair.
also remember the coils, from firewall forward, are t2,l2,t1,l1.
kevin.
01-06-2011, 04:43 AM
#42
Search for that elsewhere on this forum. I'm not sure you want to go through the trouble of buying the piece of equipment to do that on your own (although probably not expensive). However, there are some signs to look for, such as sputtering of the engine and check engine light (Pepboys can scan for the codes for you for free).
If you are over 50,000 miles on your current set of ignition coils, probably best to go ahead and change them out. But I agree with you in general; I don't like to change things unnecesarily. After all, we are not all like nycgps (a fanatical member on this forum)!
If you are over 50,000 miles on your current set of ignition coils, probably best to go ahead and change them out. But I agree with you in general; I don't like to change things unnecesarily. After all, we are not all like nycgps (a fanatical member on this forum)!
08-01-2011, 05:24 PM
#43
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Sorry for resurrecting an old thread but the instructions in this helped me out a ton! My CEL came on blinking last night and the car was shaking and stalling. Replaced all 4 ignition coils and it started up great! Thanks for a good thread.
08-05-2011, 02:35 PM
#44
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Hi there,
I took my 04 RX8 to a mazda dealer because my cat con went bad (i knew it is under warranty), now the problem is... they said that the cat con went bad because of old coils and spark plugs cousin a misfire, and if i want them to replace those part is going to cost me U$S1000. That seems a lot to me , so what shoul I do? have them change just the cat or everything? I'm not sure if I have to do something special or not changing the stuff myself. Help!
I took my 04 RX8 to a mazda dealer because my cat con went bad (i knew it is under warranty), now the problem is... they said that the cat con went bad because of old coils and spark plugs cousin a misfire, and if i want them to replace those part is going to cost me U$S1000. That seems a lot to me , so what shoul I do? have them change just the cat or everything? I'm not sure if I have to do something special or not changing the stuff myself. Help!
08-06-2011, 07:47 AM
#45
Just my opinion, but I would go back and tell these guys that the cat has an 80,000 mile warranty on it and it ain't your problem it's theirs but you'll pay for the coils IF it needs it. Was the car missing or running bad before this? I had the same problem, started the car one day and it was missing badly. I drove it 10 miles to get it home, changed out the plugs and coils and then got CEL the next week indicating a bad cat. Took it to my Mazda dealer and they replaced it, no questions asked.
08-07-2011, 10:24 AM
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Just my opinion, but I would go back and tell these guys that the cat has an 80,000 mile warranty on it and it ain't your problem it's theirs but you'll pay for the coils IF it needs it. Was the car missing or running bad before this? I had the same problem, started the car one day and it was missing badly. I drove it 10 miles to get it home, changed out the plugs and coils and then got CEL the next week indicating a bad cat. Took it to my Mazda dealer and they replaced it, no questions asked.
Supposedly the $1100 was a missquote (yeah right!).
08-15-2011, 04:25 PM
#48
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It takes 30 min max to do this and is very easy. I got mine at O'Reily's and they have a life time warranty with them. I just hope it helps with the gas mileage because my 05 get horrible gas mileage
11-11-2011, 08:27 PM
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Hi there,
I took my 04 RX8 to a mazda dealer because my cat con went bad (i knew it is under warranty), now the problem is... they said that the cat con went bad because of old coils and spark plugs cousin a misfire, and if i want them to replace those part is going to cost me U$S1000. That seems a lot to me , so what shoul I do? have them change just the cat or everything? I'm not sure if I have to do something special or not changing the stuff myself. Help!
I took my 04 RX8 to a mazda dealer because my cat con went bad (i knew it is under warranty), now the problem is... they said that the cat con went bad because of old coils and spark plugs cousin a misfire, and if i want them to replace those part is going to cost me U$S1000. That seems a lot to me , so what shoul I do? have them change just the cat or everything? I'm not sure if I have to do something special or not changing the stuff myself. Help!
Luckily I know something about cars, and also had the help of the ppl on this forum. I realize you're problem is probably in the past by now but for the sake of future visitors:
1) do NOT let the dealer tell you a misfire-related cat failure does not fall under the 80k/8yr federal emissions warranty. I had to contact the EPA as well as get consensus from a few other dealers, but I was able to strong-arm the cat out of the fraudulent dealer under warranty.
2) I would definitely replace the coils (most likely the source of your problem, and could blow the cat again if not addressed), which means you should also replace your sparks- chances are they are mildly fouled up anyways from the misfire. Coils on the RX8 do more work than on a normal car (what with our sexy hi revs) so they generally fail each 20-30k miles.
3) Get 4 coils / 4 wires / 4 sparks for like $230 on AdvanceAutoParts I think there was some discount a while back. Coils are super easy to do yourself from the top of the engine (seach DIY coil replacement), sparks are DIY too but a bit harder, may involve removing driver tire but save on labor.
Anyways warrantied cat + coil/spark/wire parts + no labor should get your baby back in working order for a little over $200.
Good luck to you
Last edited by darkrider007; 11-11-2011 at 08:30 PM.