I've looked through numerous calibrations and for some reason people at idle are running like random ignition timing. the factory manual calls for -5 BTDC for leading and -15 split to make the trailing fire at -20BTDC.

why don't people specifically just do this?!?! why the random times?? some are running 20 degrees BTDC , some are running 8 BTDC etc. why run such a retard?

 

My car seems to idle better at +10 BTDC advance than at -5 BTDC, your experience may be similar and it may be different. Don't take my word for it, try a few different values and decide for yourself.

 

With porting the engine is often going to idle better with more advance. It also depends whether you have closed loop idle ignition timing control running or not. It can also depend on ISC valve control.

 

The -5 and -20deg is not where the factory car idles. You have to jump the TEN and GND to lock the timing at those numbers to be able to verify that the timing is correct. you will notice a change in idle when jumped and not. most of the cars I work on like the 5deg advance.

EB Turbo

 

Wish there was a way to extract the stock ignition maps to get a nice base :P

 

yea use the stock base map aem offers, that is a stock factory base map

 

AEM's timing maps (the ones that come with the software download) were not built by them first disassembling the stock ECU--they're not very close to what we know of stock timing maps from Mazda. Personally I don't like them. I don't think whoever put them together knew much about tuning timing on a rotary.

On the series 4 rotaries, before Mazda introduced idle igniton feedback, idle timing was -5L -20T. The pulley marks were at -5 and -20. On those engines, when you jumpered the diagnostic connector you cancelled the idle air feedback but the timing was already fixed. The REW engines have a single pulley mark at -20. On the stock ECU, when you jumper the diagnostic connector (TEN and GND) it cancels the idle ignition timing feedback in addition to canceling ISC valve feedback.

 

just curious what is your idea on timing on a rotary then................

 

I don't like the AEM EMS basemaps timing because I think the leading is too retarded in the cruising and spoolup area, and the split map seems mostly arbitrary.

Compare the leading and split maps for the AEM EMS "Stock Twin 1600cc" basemap to the leading and split for the Power FC basemap on the old 2.01B boxes (most PFC's are version 5.01). For some reason the image tags aren't working for me, but I have attached the image files. Here is the AEM EMS leading map:

https://www.rx7club.com/attachment.p...1&d=1308329773

AEM EMS is in kPA absolute pressure units. Here is the split map:

https://www.rx7club.com/attachment.p...1&d=1308329773

The idle and off-idle area are set to 15 split probably because there's 15 split when checking ignition timing on a 1986-2002 13B engine. The 8 degrees of splt everywhere else seems pretty arbitrary to me--like whoever put the map together heard 8 split was ok so just stuck it everywhere. Here is the leading map on a Power FC with the old 2.01B basemap (most PFC's are version 5.018:

https://www.rx7club.com/attachment.p...1&d=1308329773

Supposedly that Power FC map is very similar to what's in the stock ECU. Power FC uses kind of a weird kg/cm^2 absolute pressure units, but they are close enough to the EMS map that they can be compared. Notice that there is WAY more timing in the cruising and spoolup areas. Here is the PFC split map:

https://www.rx7club.com/attachment.p...1&d=1308329773

Note that on the PFC timing in the idle area of the map is only used during warmup. After that the PFC engages closed loop idle ignition control (unless you turn it off). This isn't a perfect split map or anything and it does have some weird cells. But notice the trend of using less split during low loads and more split as boost increases?

Now look at the stock leading and split maps for an series 4 Turbo II engine.

https://www.rx7club.com/attachment.p...5&d=1308329758

https://www.rx7club.com/attachment.p...1&d=1308331059

This map comes right out of an N332/N333 ECU that has been modified to an Rtek 2.1 system. Y axis units are not in pressure. They are in a load unit that is based on the airflow meter voltage. The Power FC looks a hell of a lot closer to the T2 map than AEM in most areas. This is despite the fact that they are much less powerful than an FD engine in stock form, and they have lower compression rotors and run on 87 octane.

Just to reiterate: I don't like the AEM EMS base timing maps because they are very different from accepted practices used by most rotary tuners (on PFC, Haltech, etc) and they are very different from the maps taken out of the T2 stock ECU. It looks like whoever put it together took a map they had for some piston engine and just made a few tweaks.

 

i didn't even read that he was looking for a nice base. yea i agree aem does not supply you with a good ignition map although the files they offer do work good to get a car started. Its funny i never have looked at the aems stock ignition map cuz when i switched to aem when i had power fc i copied my ignition table over to aem because i build the map and i liked it a lot. the aem timing map is just plain stupid lol but it would start a car. i like how easy the power fc is to use but it is old technology and it has less options. Thanks Arghx for posting the maps

 

I think the kg/cm2 for a conversion is off. doing a conversion to kg/m2 yields a 1000-1.5psi 24000-34psi. no vacuum areas? and the stock map sensor only reads to 17.5psi not 3bar. What does an accepted practice 13b turbo timing map look like or have as values? 50deg adv at at 8000rpm? they definitely cant take 30 odd deg of timing at anything above atmosphere at any rpm. can you show a screen shot of an accepted timing map in an AEM format?

EB Turbo

 

The Power FC has stupid units I'll admit. It's in absolute pressure but doing a conversion to more useful "x psi of boost" is weird because of the default MAP sensor calibration and some other quirks. pressure units of 24000 is actually about 17psi boost depending on MAP sensor calibration.

You could go that high in some vacuum areas. Would it make a difference in day-to-day driving? Probably not. Some of these calibrations Mazda worked out were specifically optimized for emissions. You should see the kind of equipment that powertrain/emissions engineers have at their disposal when they are calibrating ignition timing maps.

As a general guideline I agree that's certainly not a good place to start with conventional setups. You can see that default Power FC map does run over 30 degrees at high rpm low/boost though. Oddball stuff like E85, race fuel, etc can change things.

I can show you screen shots of maps (leading and split) that I would feel comfortable using as a starting point. This would be for a typical street ported FD with single turbo conversion running a GT35-class turbo and pump gas only. Many other factors can come into play with timing and sometimes it can boil down to a bit of educated/experienced guesswork... I am not responsible for anything you do with this set of maps. See attachments.

There's certainly plenty of room for debate or just personal preference. As you said, how much max timing to give it in high vacuum/high rpm areas? How much does it even matter? How much timing at idle? Depends on the engine. Should split be flat across the rpm range or change as rpm changes? Again there's plenty of room for variations according to individual tuner preference and the individual engine. Some of it could be worked out for each motor individually but dyno time costs money and we don't have Mazda's ability to model the engine with software.

 

arghx, how come the values in your split table are positive?

 

Good point, patman. Positive values in the AEM's Ignition Difference Map will result in firing the trailing plugs before the leading plug... this is usually called 'negative split,' and I'm not aware of anyone who recommends using negative split in boost.

Thanks for sharing PFC timing maps, arghx. Even if one had access to cheap or free dyno time, it would take a long time to figure out what sort of timing the engine wants everywhere.

 

probably because I had been messing with some other engine management system right before putting that hypothetical map together. On the EMS it should be negative. On basically every other system it is a positive value. Mea culpa.

By the way, you'll notice I have 15 degrees leading in the idle area. The EMS has fully adjustable closed loop ignition control in the Ign vs Idle rpm table (under Advanced Ignition). This has a big effect on stabilizing idle as conditions change. Also experiment with retarding the timing a little bit during warm up using the coolant retard table. Ignition retard can help reduce the irritating popping/misfiring that can occur during warmup. Remember that on a stock engine, the baseline idle ignition timing is -5L/-20T, and then the stock ECU retards the timing further than that. The coolant retard table can also be used to protect the engine when you are pushing it hard and coolant temperature rises--the same can be said with the Air Temp Ign compensation table. Leaving the air and coolant temp compensation tables completely empty is a foolish oversight.

For your cranking timing advance, in my experience 15-20 degrees will make the engine start fastest. This is set under Engine Start --> Options Engine Start . Knock control is of course timing related but it really is a separate discussion in itself.