RX7 Base Timing Setup problem

[ae82ted]

We have just rebuilt an engine of a FD3S RX7 S6 with using G4X S6 Pnp ECU

We are facing some problem with the base timing setup.

With injector switched off, Timing gun hooked to Leading #1 cable. Stock trigger wheels suppose the timing mark is at 20ATDC. So we have tried to lock Ref timing as +20, and Offset 133 degree, we can see the timing mark line up perfectly. As my timing gun can only set at 0 degree minimum.

However, its very hard for starting the engine with 5 degree idle timing. So we set it as 25 degree at idle area and engine starts ok and stabilize at 1100rpm. An then we tried to check the timing again with the engine running,  lock timing at the same +20 degree at but i have to dial up the timing gun to 40 degree for the timing mark to line up again........

I would like to know if there is anything wrong with the checking setup above. or if someone can guide me the correct procedures for setting up the base timing for this S6 engine.

We tried using the base map from the G4X folder. The trigger offset is 173. The engine starts ok and seems run ok however the timing mark never line up no matter injectors on or off... I can't even see the timing mark with my timing gun set as either 60 advance or at 0...

Please kindly help. Thanks!

[Pete_89t2]

Your main problem is you're hooking up the timing light to the front rotor/#1 LEADING plug; it should be connected to the TRAILING. Below is a cut & paste from the PCLink help file that talks to setting up & calibrating the triggers on a rotary. This procedure worked like a charm for me with my FD, running a G4+ Fury (wired in) ECU. Should be the same for the G4X. Cut & Paste follows...

 

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.

[Vaughan]

3 hours ago, ae82ted said:

With injector switched off, Timing gun hooked to Leading #1 cable. Stock trigger wheels suppose the timing mark is at 20ATDC. So we have tried to lock Ref timing as +20

The lock ignition timing setting in the Set Base Timing window is BTDC so you would want to set it to -20 to make it fire at 20deg ATDC

[ae82ted]

16 hours ago, Pete_89t2 said:

Your main problem is you're hooking up the timing light to the front rotor/#1 LEADING plug; it should be connected to the TRAILING. Below is a cut & paste from the PCLink help file that talks to setting up & calibrating the triggers on a rotary. This procedure worked like a charm for me with my FD, running a G4+ Fury (wired in) ECU. Should be the same for the G4X. Cut & Paste follows...

 

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.

Thanks a lot for your tips. I've used the above suggested procedure the outcome seems good. However its just 180degree advance from the G4X bas map. Which the base map is 173 degree and now i have to dial up to 353 and getting the best result. Either injectors off and with engine running the timing map spot on.

I'm just curious if there is any more i can do to confirm i'm not 180 degree off..........with 173 offset i cant even see the timing mark. is it something goes wrong when we assembling the engine?

Thanks again.

 

[Vaughan]

9 hours ago, ae82ted said:

I'm just curious if there is any more i can do to confirm i'm not 180 degree off..........with 173 offset i cant even see the timing mark. is it something goes wrong when we assembling the engine?

[kaptainballistik]

16 hours ago, ae82ted said:

Thanks a lot for your tips. I've used the above suggested procedure the outcome seems good. However its just 180degree advance from the G4X bas map. Which the base map is 173 degree and now i have to dial up to 353 and getting the best result. Either injectors off and with engine running the timing map spot on.

I'm just curious if there is any more i can do to confirm i'm not 180 degree off..........with 173 offset i cant even see the timing mark. is it something goes wrong when we assembling the engine?

Thanks again.

 

Did you remove the CAS Trigger at any time?  (The Keyway in the crank stops you getting the Pulley wrong!) I Think you can put them at 180 Deg out (if the aircon pulley rivets are removed)

You can figure out TDC from the rear  counterweight position.. Which gives you the keyway position, which you then can figure out where the front key way should be, then the TDC form looking at an old pulley.

I cant remember the phasing as I just look at one of my old cranks!

[Pete_89t2]

On 2/16/2022 at 5:31 AM, ae82ted said:

Thanks a lot for your tips. I've used the above suggested procedure the outcome seems good. However its just 180degree advance from the G4X bas map. Which the base map is 173 degree and now i have to dial up to 353 and getting the best result. Either injectors off and with engine running the timing map spot on.

I'm just curious if there is any more i can do to confirm i'm not 180 degree off..........with 173 offset i cant even see the timing mark. is it something goes wrong when we assembling the engine?

Thanks again.

 

If the procedure worked and your timing map is now spot on, you're good. It's literally impossible to assemble a rotary engine 180* off - the E-shaft, its keying and the stat gears basically make that impossible by design. The pulley/CAS wheel bolt pattern is also keyed in such that it will only fit one way on the E-shaft pulley boss, so unless someone molested those pulley bolt holes to "make it fit" another way, it's all good.

It's nice not having to deal with camshafts isn't it?