Engine was idling funny and very easy to stall at cold start. Decided to replace my plugs.

Whats wrong with the Rear Leading plug?
The electorde is like new and the booster cap it all worn out.
Was this plug defective or is it my coils? Help me diagnose this. Any other probable causes?

From left to right ----> Front Trailing, Front Leading, Rear Trailing, Rear Leading.

 

Judging from the looks of it those things have been in there forever. Put a new set in, and recheck in 3000 miles.

 

New plugs are in right now... runs much smoother.
These must have been in the car about 40,000 kms or 25,000 miles.

The rust and dirt on the plugs is just because of all the road salt and grime around here.

 

Wouldnt surprise me. Dont get worried yet until you recheck them.

 

Worried??? Worried about what...

 

those looks "fine" for 25K miles.

change it. thats all it takes.

 

^^^ That is what I am worried about.

BTW... Those were platinum plugs BUR7EQP and BUR9EQP

 

got some good new plug wires too I hope

 

Do they wear out fast too??? I installed OE ones from Mazda last year.

 

And you didnt change the plugs at the same time? You're a strange one... the wires wear out faster when you got bad plugs in for a while but year old should be ok, got a warrantee on them? Take em back and get em switched out if you can

 

I need to check if I have a warranty on what and for what reason?

.... These past 2 years have been absolute mayhem and I have badly neglected this car... I am now in complete zen with my surroundings and now notice all that needs attention and I am now giving it what needs it.

 

on the plug wires man

 

So you want me to go to a Mazda dealership, make up some story about the wires being bad, just to try and get a free replacement because they ran on bad plugs for a year? Are you a drama queen by any chance?

If I fuckd'em up because I left bad plugs in there, I will just go and buy a new wire set. No drama, no hassle, no BS.

 

do what you want, I thought you said they might be bad

 

Still my question remains...
Does anyone have a clue why the Rear Leading plug would wear on the booster cap instead of the electrode?

 

All I can say is your motor is not running as it should.

Any kinds of corrosion/breaking on the cap not on the electrode means your motor having some combustion problem.

try to change the plugs and wires. check it again after 5-10K miles. if its still like that, its probably your ignition giving up.

but I mean your plugs look fairly good for 25K miles of abuse

 

Thanks for the input... The previous set of wires was replaced because of a bad connection on one of the plugs. (can't remember which) I will check them in a few months and see what happens. I was also thinking about getting the MSD 6A or the Hi-6. but I have to do more reseach on that and coils etc.

 

You just said your answer Bart..bad wires will cause Crap like that on your plugs..Misfire.
so,you did OK by getting New wires.you should be fine.Cheers.