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Apr 20, 2014

GTR RB26 Misfire Under Boost and Coil Pack Fix

Clint found this great video showing how one guy tested and repaired a misfire he was having with his R33 GT-R.  Most of the time when I have seen misfire issues, simple fixes can make it all work. Along with the boot leakage as shown in this video, the coil harness itself, living in the RB26 engine valley gets crispy, and will occasionally come apart in your hands.  Also the right spark plugs, can make it easier for the arc to jump in the combustion chamber. I like the fine wire iridium plugs, they are expensive but when you have a misfire you lose between 50 to 100+ horsepower. for Nissan Skyline GT-R and GT-R parts.

Watch the video, try it out on your car. A clean car is a happy car.

RB26DETT Spark Plug Recommendations
DoLuck Coil Harness (provides direct battery power to coils)

Coils are visible with left side valve cover removed to fix a small oil leak. 

I like using a t handle to remove and install spark plugs. 

This coil showed signs of water leaking down inside the valley. This was cleaned up

This spark plug showed signs of water accumulating around the spark plug. 

Double fine wire iridium plug
* R7238-7, 8,9,10.
o Replaced by R7436-7,8,9,10
+ Hand made fine wire racing plug
+ 14mm, 3/4 reach, 5/8 hex, JIS length , fine wire iridium center electrode
R7436-10 part number 4900 $ 38.81 each JIS - I like
R7116-10 part number 3179 $22.34 each ISO - I have used
R7119-10 $33.12 each ISO - Not used - should work
BKR8EIX $7.60 each ISO - Not used - should work
IFR8H-11 $11.71 each ISO - Not used - should work
NGK Racing plug 4898 R7436-8 $41.52
NGK Racing plug 4899 R7436-9 $41.52
NGK Racing plug 4900 R7436-10 $41.52

Stock Spark Plug for an RB26DETT

* P = Premium platinum
* F = 14, 19mm(3/4") reach, 16mm (5/8") hex
* R = Resistor
* 6 = Heat range 6
* A = Firing end construction
* -11 = 1.1mm gap (0.044")
Heat range for NGK plugs 2 HOT - 11 Cold

A good stock replacement spark plug for an RB26 is a BCPR7EIX. Its an NGK Iridium plug. Heat range is 7 which is one heat range cooler than stock. Its readily available in the US. I would use them up to about 500 horsepower on an RB26. Above that I would look at an 8 for a street car, cooler if its a track car.  I have had good luck with NGK plugs, I insist on them, on the race cars I work on. One less thing I ever have to worry about.

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