How to identify an engine misfire
 

Hey guys. New (as in 2 days) rx-8 owner. Love my car, but today when driving (accelerating, to be specific) the check engine light flashed once or twice, and stayed on. I've read that when an engine misfire is the issue, the CEL flashes at least a few times, if not for an extended period of time. I didn't see any dip or change in performance, either when the light came on or since it has been on, so I'm hoping it's not a misfire or something worse.

I was near an Autozone, so I took it over and had them run the diagnostic (I don't have one myself) to see what it said. The guy told me it was coming up with a "cylinder misfire," and that 9 times out of 10 with an rotary that simply means that I "got some bad gas" and that it should be fine shortly.

So, I suppose my question is what is the best way to proceed from here? Do you guys think the "bad gas" thing could be a possibility? Should I give it a few days and see if the light goes off, and if not, take it into a dealer? I bought it from a dealer, but in the next city over, and not a Mazda-specific dealer.

Car is an '05 GT. About 34k miles. Automatic. The only info on maintenance I have is the Carfax, which merely says that there were several "maintenance inspections" performed lately (as the car went through the auction/dealer process). Thanks, and let me know if there's anything else I can provide.

Bad gas?...Oh please...Don't listen to some guy from autozone...Most likely your plugs or coils...Since you just bought your 8, I suggest you go ahead and change them asap.

Yes, flashing CEL is always a misfire. Bad gas could be a reason for a misfire. But so could:
- Failing or fouled plugs
- Failing wires
- Failing coils
- Failing catalytic converter
- E-shaft sensor dirty
- E-shaft sensor profile skewed
- dirty MAF
- vacuum leak
- compression loss

At 34,000 miles, chances are it's the ignition failing. Coils, plugs, and wires brand new from forum vendors or even autozone will cost you in total less than $300, take you maybe an hour to replace everything yourself if you are learning as you go. Or grab some local help and get them changed in like 15 minutes. Please don't let a dealer rape you on charges, doing all ignition items at a dealer, with them buying the parts, is usually $700-$1400, depending on the dealer.

Or get BHR ignition + plugs for however much money and then only worry about plugs (pretty much) after that.

Recently happened to me. And for what I've been reading, seems like a common occurrence.

Yes, the fast flashing/blinking check engine light is more likely throwing a "misfire" code. In my case, everything was okay but one of the spark plugs was "dirty" - or so the tech claimed. All parts passed inspection, and they apparently "cleaned" that one plug - which I still don't believe. But whatever, car has been okay lately.

I forgot to mention that in my case I got the flashing light only at high RPM - approaching redline zone. Is that what happened to you as well? I believe the automatics have a lower redline at about 7000 RPM, correct?

Since you are past the 30K mile range, I would just go ahead and replace spark plugs and wires, and coils. At that range I would even replace all that on a piston engine anyway - that's what I do on my truck and so far so good.

My problem is almost identical to yours. I have 32k miles on the odometer and i know i needed to change my coils for sure. I will change my coils first, then if the problem persist, then i will definitely change the plugs and wires at the same time. The extreme heat is killing my car. I hope it will make it run better.

Thanks for the help. How much should I expect to pay for coils/plugs? I know everyone keeps saying not to let a dealer screw me over. But I'm really not confident with my ability to do this myself...is there any other fiscally responsible option?

Yes.

Coils are in most (but not all) local auto-parts stores for around $20 each, $80 for all 4. If not there, then go with Mazmart forum vendor here, it will be ~$140 for all 4. Dealers will charge $40-80 EACH

Plugs from BHR, Mazmart, or any other source like Amazon (yes, really), for the same price of $20 each, $80 for all 4. Dealers charge in the range of $30-$50 each.

Read my prior post where I mention the overall price and the change time. DIYs on this forum are your fiscally responsible friend.