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Sunday, August 25, 2013

RB26DETT Ignition System Troubleshooting


The RB26 is a coil on plug ignition system. This allows for the individual coil to send more voltage/current to a plug, with less duty cycle than the old school single coil setup. The R32 and R33 have a separate transistor/ignitor unit while the R34 has a built in transistor in the coils.  On the RB, the ignition coils and coil harness are located in the valley of the engine. Over time, the coils and the harness are slowly cooked in the harsh environment of the engine valley.  The connectors to the coils crack, and the terminals get loose.  The crimped connections inside the harness get corroded. Do Luck Direct Power Ignition Strengthening Kit. 
RB26 ignition system
RB26DETT ignition coils

Ignition system troubleshooting flowchart

Back to the ignition, coils, wires, etc. The first thing to do, if you think you have a misfire, or problem with your ignition system is to observe.


1) Does the car have a noticeable miss? Shaking a little, won't rev up correctly? An RB26 should idle pretty smoothly at 950-1050 rpm. 

2)Can you rule out anything obvious? Aka vacuum noise, vacuum lines off, intercooler hose popped off, electrical connections disconnected?

3) Remove center plate from engine - finishing plate, so you can access coils.


4) Reconnect igniter. Start engine. Disconnect one coil at a time, to isolate cylinder that is misfiring. If you notice no difference, then double check them all. There is another way to do this with Consult software, but standing in front of the engine, its normally very obvious which cylinder has little to no change when disconnected. 

5)When you locate the misfire, turn off engine. Pull that coil and plug. Double check all connections. Is the connector damaged? Any signs of overheating on the coil? Is it dirty? Do you see a large amount of carbon? Check the wiring harness. Any loose or broken connectors?

Missing part of the connector


6)Pull the coil boot off, look at the contact. There are two styles of contact, a carbon, and a spring. The carbons wear, the springs can also fall out. Make sure something is there, and doesn't look corroded, or damaged. 
Notice anything missing? High boost, and RPM misfire identified!



7)Pull the spark plug out and look at it. Does it look normal? Does it have wet fuel on it? Is it missing an electrode? 


8) Clean or replace spark plug. Recommend replace, but that isn't always practical

9) Clean and put dielectric grease on the bootshttp://www.gtrusablog.com/2014/04/gtr-rb26-misfire-under-boost-and-coil.html

10) Fire it up, see if that fixed it.

11) If it fixed it, then you are golden. If not, then continue

12) If the car is an R32/R33 then it has coil, igniter, wiring harness, ECU, power to fire the coils. If the car is running, the power is good, so don't bother look at the main power. That narrows it down to coil, igniter, wiring harness, ECU.

13) Next thing to try, is figure out if the coil is bad. Take the coil that showed as misfiring, and move it to another cylinder. AKA #2 was bad, move it to #3, or #1. Doesn't matter where. Did the misfire follow that coil, or is it still showing same hole as bad?

14) If the misfire followed the coil, then its probably a bad coil, replace, test again.

15) If the misfire stayed in the same location, then its either wiring harness, igniter, or ECU. Could also possibly be bad plug. Swap plug, test again.

Check out the center pin on this connector. Wiring harness


16) The last two cars I had this issue with, turned out to be fixed by removing the wiring harness from the ECU in the passenger side kickpanel, and reseating the ECU connector. It was that simple. Both cars started firing on six cylinders again

17) If this doesn't fix it, the next step is isolating the wiring harness, the igniter,and the ECU to figure out which component isn't working.


Missing a contact spring from one of the coils.  Always have a look at the contacts/springs when taking the coils off an RB. 
  • Coils - Ignition
    • Coil on plug. R32/R33 are the same.
      • The front two ignition coils on each side of the V in a early 90's Infiniti Q45 are the same  
      • 22433-60U01 
    •  R34s have the igniter built in. 
      • 22448-25U00 (coil assy)
      • 22465-59S00 (boot)
    • How to clean/repair misfires. 
Setting ignition timing and checking TDC on the RB26 in the Nissan Skyline GT-R.
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