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Discussion Starter #1
My car threw two CELs, P0300 (Random/Multiple Cylinder Detected) and P0304 (cylinder misfire 4 detected). No wonder my idle has been erratic and my gas mileage horrible. Only mod is CAI and have 48XXX miles. I don't know if this is due to dead spark plugs or a leak or a clog. Is this covered under warranty?
 

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My car threw two CELs, P0300 (Random/Multiple Cylinder Detected) and P0304 (cylinder misfire 4 detected). No wonder my idle has been erratic and my gas mileage horrible. Only mod is CAI and have 48XXX miles. I don't know if this is due to dead spark plugs or a leak or a clog. Is this covered under warranty?
It should be covered. Are those the original spark plugs?? If so, that may be your problem... they are due to be changed at 30K miles iirc. I'd would definitely swap the CAI out for the stock air box before the dealer visit. They can (and do) void warranties for just about anything. It would be worth it if it turns out to be something major.
 

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Discussion Starter #4
Yeah, I was thinking it was the spark plugs? Yes they are the original spark plugs. Unfortunately, I don't have a stock intake. Are they really gonna try and say my CAI caused a cylinder misfire?
 

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Yeah, I was thinking it was the spark plugs? Yes they are the original spark plugs. Unfortunately, I don't have a stock intake. Are they really gonna try and say my CAI caused a cylinder misfire?

What brand CAI you have?

if you have the mazdaspeed one,most likely they will do the work under warranty for you.
If you have different one then try to borrow one from a local member if any :)
 

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Discussion Starter #6
I have INJEN. There are two dealerships in my area. One is an hour away but they have decent customer service and have done all my warranty work (Clutch TSB, EGR valve, Suspension "clunk"). The other one 15 minutes has the greediest ugliest service manager I have ever encountered..

Anyway though if the dealer close by says no because of my intake then I will take it to the far one. I'll let you guys no the cause but either way, Denso spark plugs are in my immediate future.
 

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Go to the friendly dealer you have good rapport that's further away if you're not going to take the CAI off. The asshole dealer can 'flag' your car in the system and it'll pop up at other dealerships not to honor your warranty. Not sure how quick that happens, but not worth the risk imo
 

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I've had the same codes come and go over the past month or so. Within this time, I've changed the plugs, swapped bag and forth between a CAI and stock intake with no difference. The one thing that made a real difference and I have no idea why, was when Mazda touched my car and snapped a bolt on my down pipe (right on the first cat) and "fixed it." Eventually causing a leak right before the second cat and then causing the same codes (expect mine was in #3). This is when I had the codes, and after I swapped the cat out for a test pipe, it went away for the longest time. It has only recently come back, but again AFTER I was at Mazda.

Is it a coincidence that they are CONSTANTLY trying to sell me on a complete fuel system cleaning? hmmmmmm...car always seems fine to me after I clear the codes now and check it over myself. $10 says when I bring it back in for an oil change it throws the codes again.

To the OP, save yourself a trip and change out the plugs before you go. This may sound crazy, but my dealership gave me shit for not changing mine (or letting them) at 30k. If you still have problems, then take it in and tell them you already changed the plugs. One less step for you and them...


ßill
 

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Well, scheduled maintenance has it 100k miles before the spark plugs are recommended to be replaced. I would give your dealership shit for not knowing that. This doesn't mean that they last that long and that is not the issue here.

As said, I would change out the spark plugs, how they look will give you a good indication of any issues. If anything, at least pull the plugs and inspect them.
 

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Discussion Starter #11
Ok. Well I am going to change the spark plugs myself today. I am buying them from he dealership. If they are pre gapped does that just mean plug and play?
 

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Well, scheduled maintenance has it 100k miles before the spark plugs are recommended to be replaced. I would give your dealership shit for not knowing that. .......
Well, I'm going to give YOU shit for not knowing that the correct plug change interval is 45k miles or SOONER on a Speed6. Go and proof read the FSM or your OM
 

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Discussion Starter #13 (Edited)
Well, I'm going to give YOU shit for not knowing that the correct plug change interval is 45k miles or SOONER on a Speed6. Go and proof read the FSM or your OM
Forzda well I am sorry to disappoint you. As an engineering student, I don't have the time to do all the mods you did and treat the owners manual as a bible. I take care of the car and try to do all maintenance on time so I am sorry that I was senile enough to forget about changing spark plugs.

I asked for gap measurements, not your opinion.

Edit: Somebody said the gap is .032. So I guess that's what I will use then.
 

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Forzda well I am sorry to disappoint you. As an engineering student, I don't have the time to do all the mods you did and treat the owners manual as a bible. I take care of the car and try to do all maintenance on time so I am sorry that I was senile enough to forget about changing spark plugs.

I asked for gap measurements, not your opinion.

Edit: Somebody said the gap is .032. So I guess that's what I will use then.
I'm pretty sure he was talking to the guy who said to give the dealership shit for not "knowing" the recommended plug service was at 100k when in reality it's at 45k.

And .032 is what I've seen as correct.
 

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Discussion Starter #15 (Edited)
I'm pretty sure he was talking to the guy who said to give the dealership shit for not "knowing" the recommended plug service was at 100k when in reality it's at 45k.

And .032 is what I've seen as correct.
Oh well then if Forzda wasn't talking to me sorry for being so defensive. :tear:
 

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Discussion Starter #16
I changed the spark plugs and all I can say is WOW!!! The car hasn't felt this smooth in months and it is definitely not in my head!!! It feels 200% better. The idle is steady and the engine revs like butter compared to before.

For one, when I took out the spark plugs they looked pretty worn with corrosion on the tips and some oil near the beginning of the thread but on top of that they were gapped at .029,.026,.030 and .029. WTF!!! Does that mean they are not even properly gapped when they are put in the car in the factory???

Anyway I am 92.84% sure the misfire code will not come back again. My car is 2 months/1100 miles away from being out of warranty so I hope that the car lives a healthy and long life. Thank you to everybody who suggested that I change the spark plugs.
 

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Well, I'm going to give YOU shit for not knowing that the correct plug change interval is 45k miles or SOONER on a Speed6. Go and proof read the FSM or your OM
You sir are correct, my comment was major fail. Never paid attention to scheduled maintenance on spark plugs. I've changed them out at 23k mile intervals so far and I think that is too long. I get lazy.
 
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okay gents, tell me, what spark plugs i should buy for my MS6. sure i got the gap .032 /// but what brand, if it matters, should i get, or more importantly what brands do i need to stay away from?
 

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I bought the NGKs. LOVE them so far. Changed them out about 40k from OEM and my OEMs did not look that bad. But my gas mileage jumped up a lot and the car def runs smoother.

ßill
 
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