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I'm trying to hunt down an intermittent miss. My injectors all ohm in spec (at the injectors and at the ECU), all connectors are clean
and in good shape, new TPS (calibrated properly), new CAS, new PTU, new fuel pump, basically everything is new except the O2
sensors (which I'm beginning to suspect anyways).
I had a pretty bad stutter/miss under low RPM/high torque situations, and I swapped out all of the coilpacks on the passenger side.
It still had an intermittent miss at idle, but it drove much better. I ordered a full set of coilpacks from Bernie, installed them and
drove around. After a few days, I noticed it was still kind of there.
So I started dissecting my massive stock of coilpacks to see the differences. Some have different part numbers, some have the
Nissan part printed on while others have raised molded lettering, some have round casings, and some have a flat side. The most
significant difference, though, is on the inside of them.
The coil itself is the big lumpy thing around the top. There's an extension in the middle, and a rubber sheath at the end. These three
parts easily break away from each other. Using the below image, there are three styles (from left to right):
1. Printed Nissan lettering, extension and tip use a very thin spring with a solid wire in the middle (brass "caps" to receive the spring
at the top of the extension).
2. Raised Nissan lettering, extension is hollow with a single spring going all the way through (from coil to tip). This spring is slightly
thicker than the other two styles.
3. Raised Nissan Lettering. Similar in design to No. 1, but with little metal (magnesium?) caps at the end of the springs in the
extension and coil. I tried ohm testing the extensions themselves. No.2 seemed to have the most stable reading, but with the other two styles, even
the smallest movement would send the multimeter all over the place. However, No.2 also seemed to have the worst contact surface
to touch the spark plug (as the tip of the spring wasn't as flat as No.1 or No.3. In any case, I still can't seem to figure out my intermittent firing problem. It doesn't seem to be specific to a single cylinder, and
there's no consistency at all. It's most apparent at low RPM/high torque situations (ie taking off from a stop) or at WOT. Any
ideas...?
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Coil Pack Differences - 
