Only Error message is: Random Misfire

[BigB]

This just happened to me tonight.

Code PR0300, random misfire. Felt like the car dropped a cylinder or two.

I pulled the plugs and this is what I found:

Could this be the culprit?

Unfortunately I did not pay attention to what order they were in when I pulled them out since I was just looking at the electrodes. It wasn't until I laid them all down next each other that I noticed what appears to be burn marks.

 

[bazooka joe]

(uhm) the color of the electrode doesn't look really bad, but the porcelin is really burnt looking? weird?(confused) never seen that? so did you change them out? how's it run?
good burn:

 

[BigB]

Changed them out last night after those pics.

*Seems* okay but only drove it around the neighborhood so no real load on it.

CEL was still on of course.

I drove the roommate's Tundra to work today instead.

 

[bazooka joe]

Changed them out last night after those pics.

*Seems* okay but only drove it around the neighborhood so no real load on it.

CEL was still on of course.

I drove the roommate's Tundra to work today instead.

reset that cel!

 

[shane02pro5]

Maybe a coil going bad?? Mine have gotten pretty burnt looking but all the same and those look pretty new too! Also I'm not sure what they call for gap in the manual but I know they come gapped to like .050. At lower boost I always did .032.

 

[BigB]

The -11 on the plug code indicates a gap of .035 I believe.

I just spoke with Mazcare and they think it's most likely a coilpack/wires going bad.

What is the general lifespan of those parts?

 

[shane02pro5]

I still have my originals with 95k on them and abused regularly!

 

[Mogli]

everyone with misfire problems should check their fuel filter. the one thats attached to the pump in the tank. i was told you never have to change it since its sock style. i changed mine and my car runs so good now. fixed my problem. dont overlook the most simple thing

 

[Diehonda]

Fuel pump is expensive, so I'll eliminate that one.

Coils -- the last thing the mechanic wants to check is the ignition module. I've read on this forum about Ignition Coils -- if it is the ignition coils, will it be evident after checking the ignition module??

Or when you say coils, do you mean the coil pack? I'm guessing that's different than the ignition coils, anyway. The mechanic checked it, but from what I've read on the forum, it can look okay, but still be bad. (scratch) Is that something that you just replace while hoping?

Replace both ignition coils, reset the ecu, enjoy.

 

[BigB]

replaced plugs, reset ECU.

tried to "recreate" conditions that led to the CEL and nothing happened.

Drove the car all weekend and this morning with no issues so far....

(shrug)

 

[army88brat]

Hey guys, I was reading the other thread down below and I am really suprised that I am not the only one dealing with this problem. So here is the info:

2001 Mazda Protege ( dont remember off the top of my head what specification it is like es, lx, whatever)
almost 120k on it.
bought it from a dealership 4 months ago.

I was driving it around for a week after I got it. And the CEL came on blinking. I don't remember what the symptoms where. But when I saw it I pulled over. The rpms where going down and the car was shuddering and I turned it off. Let it sit awhile like a few mins. Then turned it back on, it was fine, and the CEL was on just not blinking. So fast forward 4 months of that happening very often. I got the CAT replaced, and now both O2 sensors replaced at the dealership's shop.

Now I drove it off the lot yesterday hoping that the problem was solved. I turned around because I forgot some stuff in the loaner car that they provide and the CEL was blinking AGAIN!! When I drive though it the rpms kinda shudder if I slow down and stop at a light, but that is all. Then the light goes from blinking to solid. So they people at the shop pulled the code and it was a Random Misfire. They cleared and said just drive it. They said that they drove it a week and never got it to misfire. So then last night I turned on my heat and right when I did that the CEL came on, called the mechanics and they said to bring it in tomorrow. So when I was driving today down the highway at 69 mph I felt a little jump or something and I knew it misfired and it did. When the codes where pulled it said Random Misfire P0300 (i think that is it, it is that one) and CAT.

So now the Catalytic Converter has come on more frequently. And I remembered that the random misfires didn't happen until I got the cat replaced. And the mechanic said that the code from the cat means that it is bad again and needs to replaced. But it is warrantied so no biggie.

I posted this somewhere else on the forum and haven't got any answer. But where are the coils, and what do they do?

 

[army88brat]

not a protege 5 but I have seen on the another thread about protege about the coils.