Hey, I've got a 99 Milly S, and error code p-0302 (i know its not a reg code, amazda techchecked it for me) indicating a cylinder 2 misfire.I just had the plugs replaced, but its still running rough, also this is intermittant so its hard to diagnose at a shop. Does any one have any suggestions on if replacing a coil would help (220 cost, 320 retail) or any other solutions? thanks in advance!

 

wow. are you being hosed. ign coil, KJ01-18-100C MSRP 174.80. check out:

http://www.trademotion.com/partlocat...;siteid=214627

this one is slightly less, but the one pictured is different from a factory coil. you need to verify it is correct:

http://cgi.ebay.com/ebaymotors/New-M...QQcmdZViewItem

P0302 is a regular, specific DTC. cyl #2 misfire. now, first question, what plugs were installed? the 2.3 has different plugs. if whomever installed them dont know, it is possible the wrong plug is in there. and, if it is hard to diagnose at a shop, then the shop dont have no simple scan tool, and i wouldnt let them work on my lawnmower. the factory plug is ngk PZFR5F. gap is .7-.8mm. if the plugs installed have a -11 after them, they are wrong. again, dont go back to that shop, except maybe to get a refund. and dont go wierd and get buttco plugs like iridiums.

you are lucky that cyl 2 is the front bank, passenger side. front bank cyl is 2-4-6. rear is 1-3-5. front bank plugs are easy to get at, takes about 30 min. you pull the front intercooler(2 nuts, 1 bolt, 2 hose clamps), then each coil is exposed. if the plugs are the correct ones, then i would swap the coil with one of the others, and see if the miss follows. if so, then you need a coil. used coils are cheap, unless you GOTTA have one, then you can never find them, and gotta go new. i picked up a whole set off ebay for 20 bucks. also, an early(95-96) coil will work, it just has an extra pin that is not used on the later cars. i have 1 of the early coils in one of our cars(we have 2 99s'). oh, and who the heck is selling you a coil for 320? or even 220? i hope it aint a "friend"

 

SorryI should have been more specific, the error codehappened before the plugs were switched, unfortunetly I don't knowwhat plugs were used, the shop was brutal, and i'm not goingback there. The misfire happened after the plugs were switched also, thanks for the cyl layout, is a coil difficult to change? It was another shop that told me the coil price, so i'll gladly take your advice and find a cheaper one, is there any other cause of a misfire? would the wires possibly be the problem? The shop that did the plugs did not specify if they did the wires, so i'll have to call and check, but something tells me that they did not,
thanks for the quick feedback!

 

it is impossible to switch the wires. there are no conventional high voltage plug wires, it is a coil on plug(cop) system. each spark plug has a coil. the connectors to each coil are just long enough, and positioned just for each coil. in order to switch the wires/connectors, one would break them badly. the front coils are easy, the back coils are a bitch. a lot of the time, a shop will charge for changing the rear plugs, but never do it, because there is so much labor involved. when you open the hood, look at the front intercooler. this has to be removed. on the driver side of the ic, there are 2 nuts(12mm). on the passenger side, there is one bolt, and farther along, there is a silicon hose, with 3 spring clamps on them. the spring clamps are tricky, the 2 smaller ones are designed to be expanded, then a tab locks them in the expanded position. you only have to remove/loosen the front small clamp. the larger clamp i use a vice grips on, open the vice grips so the jaws just start to clamp down on the spring clamp, then close the vg, the clamp expands, and leave the vg on the clamp. you then gotta muscle the ic off. when it is off, you will see the 3 coils/connectors. each coil is held on by 2 4mm(might be 6mm) bolts, each with an 8mm phillips head. however, before you unbolt them, remove each connector. this is again tricky, you have to press down on a tab on the connector, then pull off the connector. much more difficult than it sounds. what i do, is press down on the tab with a screwdriver, and pry the connector with another screwdriver. there is a tiny lock tab on each coil, and if you do not press down on the connector release, you will break off the tab on the coil. you remove all 3 connectors, then unbolt and remove the coils. mark the #2 coil, swap it, reassemble, then start 'er up. if the miss goes to the swapped cyl, you got a winner. if you are near krum, texas, bring the car here, and i will do it for you.

 

I have the same problem, with the same year vehicle. Have changed the plugs, no difference. Have swapped coils and it still indicates cylinder 2 misfire. What might be next on the list of things to check?

 

did you clear the code(s) each time after you switched/changed stuff?

 

Yes. The ECU was cleared. Is it possible that a faulty (dirty) fuel injector is the culpret. Most of the time putting the engine under load, gets it out of its 'chugging' 5 cylinder firing mode back to six.

 

what plugs did you install?

 

Replaced them twice. The first time with stock plugs from the dealer,NGK PZFR5F's and the second time and current plugs are the ngk irridium equivilents.
BTW I really appreciate your help.

 

first off, most of the iridiums are gapped way to big(.7- .8mm is correct, most of the iridiums i see are 1.1mm). personally, i would throw those iridiums.
a while ago, the black car developed a similar problem. random miss, and 2 cyls specific. i changed out all the plugs, and all 6 coils. fixed it completely. this happened right after a fill up, i suspect water in the fuel. i had also thrown in a couple bottles of heet(dri gas). just recently, the identical scenario happened. miss at idle, ce lite, both random miss, and #5 specific. we had just endured several days of record rainfall, and some major street flooding. i suspect my wife ran thru some very deep water. actually, i know she did. since she drives the black car, i couldnt take a chance, so i changed out all 6 plugs, and also put in a new #5 coil(#5 is a bitch to get to, it is the worst one of the bunch). while it was better, there was still a slight miss at idle. so i threw in a couple bottles of heet, and the miss gradually went away. after about a half tank of gas, it was gone, and the car was normal. just for grins, i put the suspect bad coil into the white car, and it is still there, working perfectly. you should try a bottle of one of those total fuel system cleaners, and at least a bottle of heet, maybe 2. that might fix it.