Ive been changing my plugs. I change one a month- did the front three, then the passenger side firewall side one, then last month did the middle back plug.
After changing the middle back one i would get when stopped at idle a sharp/quick rpm drop or kick that you could see in the tach and feel sitting behind the wheel. I changed the middle coil pack and it went away.

When I did the final plug change (firewall side , drivers side) I said well all the people bitxx about the poor 99 coils so i bought a new 99 coil (standard intermotor brand made in poland) I changed that plug and put on the new coil. Started engine that night twice, no problems, wife started it next morning to go to work and check engine light came on.
I went to autozone they said ignition pack problem, but did not know which cylinder- also said there was a knock sensor code.
I put the old hanshin coil back on, drove it 210 miles and light went off. have driven it another 400 miles- no light.
What caused this/ could a bad coil throw a check engine light on the 3rd engine start?
And can dealers or repair shops tell you which coil is bad?
If bad and they say replace all 6, and one of the 6 is bad from the factory? then what? replace all 6 again??
Strange to me?
Any ideas?

 

Coils can cause a check engine light - P0301 for cyl 1, P 0302 for cyl 2, P0303 for cyl 3, P0304 for cyl 4, P0305 for cyl 5 and P0306 for cyl 6. The last plug/coil you changed (firewall side, drivers side) is cylinder # 5, so the check engine light code should have been P0305. Did they ever tell you what the code was?

Since you swapped the original coil back and the problem went away, obviously the new coil was defective. Take it back to the store and get your money back. Also you need to learn from this - namely that just because a part is new doesn't mean it can't be bad. It could be bad out of the box, it could fail after 3 or 10 or 66 or how ever many starts you want to theorize about, but just because it's new doesn't guarantee it will last as long as the old part did.

To replace all 6 coils at one time depends on how you feel about spending money and working on your car. All you really have to do is replace just the defective one. When will the next one go bad? Who knows.

And your last question "and one of the 6 is bad from the factory? then what? replace all 6 again??" Come on man... Use the old gray matter upstairs. Of course not.

 

My last question about replacing all six was to try to answer people who said there was no way to tell which pack was bad, and that dealers also told them that. Thus I did not believe that the dealer / good mech shop did not have a way to see which coil was bad, i.e. they would not replace all 6.
i will look on the auto zone print out to see what the code was

 

[QUOTE=DennisMik;7859174]Coils can cause a check engine light - P0301 for cyl 1, P 0302 for cyl 2, P0303 for cyl 3, P0304 for cyl 4, P0305 for cyl 5 and P0306 for cyl 6. The last plug/coil you changed (firewall side, drivers side) is cylinder # 5, so the check engine light code should have been P0305. Did they ever tell you what the code was?


the autozone store said the code was P1320 and gave me a print out tht said OEM number to cross- P1320.
Troubleshooting P1320
OEM Infiniti
Ignition signal, primary circuit intermittent.

------- is that a nissan code? P1320?

probably cause
open or short
poor connection
failed transister

 

P1320 is a code used by Nissan. The OBDII standard has a bunch of codes that are used by all manufacturers and then the manufacturer can add their own codes. I forget how to tell which code is universal or proprietary.

According to the FSM, P1320 is caused by "The ignition signal in the primary circuit is not entered during engine cranking or running." Possible causes of P1320 are:

* Harness or connectors (The ignition primary circuit is open or shorted.)
* Power transistor unit built into ignition coil
* Condenser
* Crankshaft position sensor (REF)
* Crankshaft position sensor (REF) circuit

I guess the easiest thing to check is to see if the wire harness connectors are on all the way. Maybe one of them isn't seated all the way. Maybe another coil pack is going bad, and maybe the crankshaft position sensor is creating the problem.

 

If you need a FSM, you can download it from
http://www.nicoclub.com/FSM/ or
http://www.aubreyandcharles.com/ServiceManuals/

P1320 is in section EC. Section FWD is the cover page of the manual and section IDX is the master index but each section has its own index.