Hey guys. Well, after putting headers on my car and throwing off my A/F ratio for a while, I got the good old P0300 (random cylinder misfire), and I suspect it might be one of my coils. I saw this in another thread, and wanted to ask about it. Is this an accurate/safe way of isolating which coil is bad?:

"I suggest you take off the spark plug cover and unplug those coils one by one and see if the idle changes. Then do the same for the rear coils. This will tell you which coil is bad."

 

sounds right. lots of threads on this.

 

yeah, i know but i only saw this procedure in 1 of them, and i just wanted to make sure it was:
1: safe to do
2: an accurate way to tell which coil is bad

 

Yes, that's all you need to do. That just narrows it down to a cylinder, doesn't necessarily mean it's the coil.

Also that procedure has been posted countless times on the org, more than enough for you to have confirmed; probably a good 20 times by myself at least.

 

This will work if you get the continuous misfire, i.e. one (or more) cylinder's not working. In some old thread the guy claims, if you pull the code before the SES starts emitting light, you have a good chance to narrow the problem (i.e. get the code about specific cylinder).

 

well, i got the car scanned 3 times since i put my headers on... the first time i got it scanned, the misfire code came up.. the second time the misfire code did not come up.. and the 3rd time the code came up again.. so that means it's intermittent i guess? what exactly does that say about the problem?

 

my bad, i havent seen those posts.. so if i narrow it down to a specific cylinder, that means it could be:

1. coil
2. spark plug
3. injector

anything other possibilities?

 

just shining in, MAF? i didnt know it was linked to my entire car's codes.

Juan

 

my 2000 maxima has the same problem an intermittent misfire on cylinder no 4
me and nissan changed all coils plugs and i still get the problem every once in a while
my code is 1320 primary ignition i dont get it the first cause on the lists is coils

 

Actually, the first cause on the list is harness or connectors. The code can also be thrown because of the CKPS REF, if you read the list.

Check continuity on the harness, and check the CKPS.

 

just an offhand guess:

Did you have the recall done for the Crankshaft position sensor??
I think there was another recall for a similar engine sensor as well....

Prob. not it....but just thinking outloud.

Is it stumbling or misfiring? I've had odd-ball SES lights come and go, sometimes without doing anything more than unplugging the battery, or resealing the gascap.

I can't WAIT for my coils to start going bad.
I have 3 months and 8k left on my extended warranty....then it's all down hill from there!!

gr

 

no, i havent had that recall done

 

anybody?

 

I wonder if you could get a performance coil that would be better????

 

If it's misfiring, it could be those three, or it could be an internal problem. Those three are the most likely, though.

 

There's no point, really. Stock ignition is capable of more power than you're ever going to make.

 

I was getting the random misfire code a while back so I bought 6 coils and replaced them. Problem didn't go away. It didn't happen often but it was enough to annoy me as to why. Then I got my phenolic spacers and the problem went away. So i wonder if I had a tiny leak in the intake manifold gasket somewhere causing the one cylinder to run too lean and cause a misfire.

 

which harness to da coil ecu input or crank pos sensor

 

Look at the FSM, you'll see.

Coil harness, and CKPS REF (not POS) sensor/harness.

 

Yes, thats the correct way to do a simple power balance test. If you find out which cylinder is not firingl=. Just swap it with a good coil from another cylnder on the engine and listen for rpm change. If thats it, your good to go and back on the road. good luck