motorrotor

I have heard and read that you adjust timing after you have completed the AFR tuning (fuel and boost).

I have had a few people tell me just don't mess with the timing at all and to just leave it stock because the amount of Power/Torque increase you will see is minimal yet you take a chance of causing detonation if you advance too far. I remember reading you might get 5 to 10 horsepower with optimum ignition which requires a dyno and then you would back off timing by 2 or 3 degrees for a safety margin.

I am currently running an AFR of 10.2 at 18 pounds of boost (3mm Seals, Ported, single turbo, Ignition Amp, PFC with Commandor Software.... etc) but still have the stock Leading and Trailing ignition times except for idle and low load. I installed 1200 primaries and 2400 secondaries and have the fuel turned all the way down (including a negative lag time) at idle but it was still smoking so I advanced the timing at low end by 10 degrees to give the fuel a little longer burn time to try and clean up the exhaust.

My concern is at high RPM and High Load. Should I advance timing 10 degrees... 15 degrees...since I am running with so much more fuel and boost to give it more burn time? I am not worried so much at getting optimum timing but I am sure that with more fuel and boost I probably should be able to advance it some but still remain below the critical point of detonation.


Should I advance both Leading and Trailing by the same amount so I maintain the same split as the stock ignition or should I lower the split?


How much can realistically be gained in power/torque by optimizing ignition on a dyno from the stock settings?

moconnor

iTrader: (14)

I would spend a lot of time reading in the PFC forum (or forums on this board for other ECUs).

Advancing timing 15 degrees from stock at 18psi would not be clever.

arghx

iTrader: (3)

On a practical level, most people start with a timing basemap that is matched to their mods and then advance or retard it from there. try checking out the timing maps in the PFC basemaps from BDC motorsports. http://bdc.cyberosity.com/main.php?g...2_itemId=14797

With fuel and timing here are the basic principles to consider:

If I advance the timing, what is the % change of power increase versus the % increase risk in detonation?

If I retard the timing, what is the % increase in safety margin versus the % decrease in horsepower?

If the timing is too advanced for your setup, retarding it will make it much safer. If the timing is too retarded for your setup, advancing it will make noticeably more power.

For fuel:

If I lean the mixture, what is the % increase in performance versus the % decrease in safety margin?

If I richen the mixture, what is the % increase in safety margin versus the % decrease in performance?


Usually you can't directly quantify any of those things, not with the equipment and methods that hobbyists have at their disposal. What ends up happening usually is that you want to tune it to a point of diminishing returns... while keeping in mind that you have to allow for changing weather conditions. So if my tune is 11:1 right now under WOT, when it's cold outside it might lean out... or it might richen up depending on how you adjusted your IAT correction table. Either way, AFR is going to fluctuate with the weather some. Usually with higher intake temps the engine can't tolerate as much timing, and there is no knock control on a PFC, so you have to build an extra safety margin into that as well.


Also, exactly which injectors are you running? Sounds like ID1000 on the primary and ID2000 on the secondary

GoodfellaFD3S

iTrader: (213)

You may want to consider having it professionally tuned, the best I've dealt with is located out on Long Island:

http://www.enzo-racing.com/

Not around the corner, but well worth the trip.

motorrotor

Thanks for all the information and reference reading to check out.

I am running Lucas 1,200 primaries and Siemens 2,400 secondaries with an FJO injector driver. Thought I might run E85 sometime. I already upgraded my injectors once from stock to 660 primaries and 1300 secondaries but I ran out of fuel capacity and 14 psi and 376 HP so I upgraded again.

arghx

iTrader: (3)

Do you have lag (dead time) vs battery voltage information for those injectors? Preferably dead time when used with a peak-and-hold driver

motorrotor

Yes. I have the lag time for both both of them. The Lucas 1200's I have the lag time from 11 volts up to 15 volts in 1 volt intervals.

The 2400's I only have a single lag time which I think was at 14 volts.

If I input the mfgs lag times, especially with the 1,200's I run way too rich so I have experimented with lower lag times and as of now I am at a primary lag time of -0.1 and my fuel map at idle is at the lowest possible setting. I still idle at an AFR of 10.6 so I just advanced my timing yesterday by 10 degrees to see if it would do anything but I didn't see any change in the AFR at idle.

Not sure but I think the ignition is controlled outside of the map at idle unless I change the settings but I'm not sure on that.

arghx

iTrader: (3)

The ignition is -5L -20T just like stock (same value that is in the FD service manual, same as the timing marks on an FC3S crank pulley). With electrical load it is 6L -4T I believe. I don't recall the timing for when A/C is on. The timing will fluctuate up and down around those values when idle ignition control is on in order to stabilize the idle. You can run open loop idle ignition timing control by setting all three idle speeds to 0.

See this thread: https://www.rx7club.com/3rd-generation-specific-1993-2002-16/how-make-your-untuned-pfc-basemap-safer-idle-better-no-datalogit-needed-841706/ specifically this post https://www.rx7club.com/showpost.php...0&postcount=27