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'88 Mazda RX7 Rotary with a G4 Storm

Mike Peissner

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I just finished rebuilding a Mazda turbo 13B rotary and I am having problems getting it running again.  Prior to the rebuild, it was on the road for about 18 months but it was always temperamental. The Storm ECU was originally installed by Rotary Planet, a company which has since disappeared.  I have been finding a multitude of minor sins (bad wiring) but no smoking gun.

Currently, I have spark on the Trailing plugs of both rotors but nothing on the Leading plugs.  All 4 plugs spark strongly using the PClink Ignition Test feature.

Also, what sample Base Map would be a starting point for my engine configuration?  Attached is the map that was built by Rotary Planet.  I am trying to compare their custom map with a base map but some of the ignition and trigger settings are so different (like the Trigger Set Base Timing) that I can't make heads or tails of it.

Would you do a quick scan and see if you can find anything obviously wrong?


Reno, NV, USA   


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I'm getting frustrated.  I have gone through the ignition wiring with a fine-tooth comb, correcting the problems (and weak points) as I found them and the problem is unchanged.  #1 rotor sparks (both leading/Ign 1 and trailing/Ign 3) but #2 rotor does not (Ign 2 and Ign 4)!

I am using Spark Direct mode and all 4 Ignition outputs spark when I do the PCLink Ignition Test.  So what triggers the 2nd rotor?

The engine is a 13B and the CAS has 2 rotors. The top rotor has 2 teeth and the bottom one has 24. Could the G4 Storm not be seeing the signal from 1 of the 2 teeth?  Is there any way to check that?

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I can't seem to change the Lock Ignition Timing or Adjust Offset settings under Triggers / Calibrate / Set Base Timing.  Currently, the Lock is at 0 degrees and the Offset is -25 degrees.  I can change the values in the Set Base Timing window but when I return to the previous window (Triggers / Calibrate), the values are still 0 and -25.  And no combination of F4 and cycling ECU power changes that. 

Is there some step I am missing?

One other thing: In the Calibrate window, the Lock and Offset values have a closed lock icon beside them.  Does this indicate the values are actually locked or that they simple have to be change in the Set Base Timing window and not the Calibrate window?

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Hi Mike

I suspect when you are changing the figures you are missing hitting the enter key after.

The figures are locked so that they can only be adjusted when you are in the set base timing window.

  The normal procedure used to set Trigger Calibration does not work so well on Rotary engines.  A piston engine will run happily with ignition timing set to fire on TDC.  This is not so for Rotary engines.


  Note: Most Rotary engines have a timing mark on their front pulley at 20 degrees ATDC.  It is the tuners responsibility to confirm that the engine has a mark at 20 degrees.  If the mark is at some other position, that position should be substituted in the following procedure.  Late 13B engines only have a 20 degrees ATDC mark.  Early 13B engines have a 5 and 20 degrees ATDC mark.  12A Engines have a 0 and 20 degrees ATDC marks.



Rotary Trigger Calibration Procedure


  The idea of this trigger calibration setup method is to end up with the leading spark firing at 5 degrees ATDC and the trailing spark firing at 20 degrees ATDC.


1. Disable the fuel injectors by selecting OFF as the Injection Mode under the Fuel heading. This will ensure that the engine will not attempt to start while the ignition timing is being calibrated.
2. Enter a value of -20 degrees in the Trailing Split Table in all the cells around the area where the engine will run during trigger calibration.  It may be necessary to set the entire table to the same value.
3. In the Triggers->Calibrate menu, click Set Base Timing.  The Set Base Timing window will open.
4. Enter 0 as the Lock Ignition Timing To value to be used (remember to push enter after changing the number).
5. Attach a timing light to fire off the TRAILING spark of the front rotor.
6. Crank the engine while watching for consistent ignition operation at a fixed crank position.  Adjust the Offset until the ignition is firing exactly on the 20 degrees ATDC timing mark.
7. Select Done to close the Set Base Timing window.
8. Enable the fuel injectors by selecting the relevant Injection Mode.
9. Perform a STORE so that the Trigger Offset value is permanently retained.  Remember that the Trailing Split table has been modified so be careful not to Store changes to that by accident.
10. Repeat the above procedure once the engine is running (ideally at about 2000 RPM) as it is hard to get accurate timing readings during cranking.  To do this, repeat the above procedure without setting Injection Mode to OFF.


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