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Im going down he highway at 80 mph and i get a rpm spike from 1500 down to 900rpm then back up then back down then it stopped. Then two miles later i hear a pop and the car starts to sound like its missfireing. so i pulled over and pulled up the hood and my number 4 plug wire is sitting on top of my engine with the center of the plug still in it. the bolt part is still in the engine. I have a k8 in it. what i want to know is do you think its a fault plug or am i going to have to replace the motor. there were no engine lights that came on and the engine still runs but not smoothly of course. the timing belt was just replaced 2years ago. i have not ran it since and have not replaced the plug. any ideas?

more than likely, it was just a bad plug... I would recommend getting a compression test done to make sure everything is alright across all cylinders.

Also would recommend changing all of the sparkplugs and maybe the wires. When was the last time the wires or plugs were changed?

Agreed. That should fix the problem and make sure it was nothing other than a plug that was WAY past time to be changed.

the plugs were replaced a year ago but ive been riding them hard They were bosch platinum single prong plugs. Good call on the compression test. Thank you for the quick reply and the help.

it's been suggested to only go with the copper plugs too.....i guess others run too hot

chatterbox4507 wrote:the plugs were replaced a year ago but ive been riding them hard They were bosch platinum single prong plugs. Good call on the compression test. Thank you for the quick reply and the help.

with that.. I would recommend going to back to NGK plugs.. so far they have provided me with reliable service. I have tried others and were more waste of money then anything else...

So these plugs you buy only at Mazda John?

Usually how much do they go for? and would I use the same kind in the K8?

DEB

I did a compression test and all was well!!!!! ive replaced the plugs and wires. I went with ngk plugs and taylor 8mm spiro pro wires. Engine fired first crank and runs great. Id say never buy bosh plugs. Thanks again for the fast help! and Id like to give praise for this great site. Thanks guys for the hard work keeping it going!

mymx.3 wrote:So these plugs you buy only at Mazda John?

Usually how much do they go for? and would I use the same kind in the K8?

DEB

i got mine from autozone for like $6 each
u can also get them from crappy tire or anywhere else. and it'd b the same brand suggested for the k8 yes, tho i don't know if its an actual diff part #

I got soem nice NGK V power and i must say they are BETTER than the crap bosh polatinum i was using.