opinions on EFI AFR and Timing maps for twin plug please
 

Hi

looking for opinions on these maps Ive made for TPS/RPM base time and TPS/RPM base AFR- just want to make sure theyre a decent starting point. I've gone through the following threads and tried to make what I felt was a best-ish starting point

http://forums.pelicanparts.com/porsche-911-technical-forum/975423-official-efi-ignition-map-sharing-thread-2.html

http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/1048209-twin-plug.html

http://forums.pelicanparts.com/911-engine-rebuilding-forum/772299-ignition-advanced-twin-plug.html

http://forums.pelicanparts.com/porsche-911-technical-forum/1002844-please-educate-my-twin-plug-ignition.html


maps:

https://i.imgur.com/QoLk79D.png

https://i.imgur.com/lFEJApr.png


engine: 1983 3.0L converted to twin coilpack, 964 cam, 11:1 JE piston, EFI ITB using triumph ITBs, stock injectors are 27lbs but running at 60psi so thats about 31lbs, haltech elite ECM and I have cylinder head temp, clewett cam, cleweet crank, TPS, MAP (using TPS for now will eventually switch to MAP)

50 is the % throttle opening? 2000 RPM at '50' you have 34 degrees. 2000 RPM at '100' you have 23 degrees. 50% throttle at 2000 RPM is the same as 100% throttle opening as far as cylinder filling is concerned. Low cylinder filling means less pressure, requiring more ignition advance.

This video may also help: https://www.youtube.com/watch?v=_GDZxUVTplk

What is your load axis? MAP or TPS? Either way, they need different (non-linear) scaling.

I think it is too rich at all the high load sites (above 55 x-axis). I usually target 13.1 up to peak torque then to 12.9 beyond to lessen the torque fall off at high rpm/high load.

Why do you increase the timing above 6500 rpm? That should be pulled back 1-2 deg.

Starting point: keep it simple.

AFR targets are safe. For a non-competition setting, you're not going to see a difference between 12.5, 12.6, and 13.0. If TPS, 20% load and 100% at 2000 RPM are the same. Use 14:1 < 10, 13.5 for 10 to 20%, and 12.5 for 20%+ above. 15:1 or 16:1 might be possible in the future at light load points for better economy.

Take the 'vacuum advance' out of the the timing curve as a starting point and do some logs. Make sure ignition timing doesn't jump around at slow speed/small throttle openings otherwise you'll have instability.

I don't think twin plug needs as much advance as you have.
It looks like you have conservative fuel ratio targets and aggressive timing. But others know more than I about these things so I'm curious to see what folks respond with.

This is the fun part though!

TPS - sorry. thats not whats in the ECM yet that was just my piss poor attempt at trasnlating a couple of what seemed like close maps while sitting at my work pc.

from the 'share your map' thread this is whats currently in and it ran better than it ever has - but this is from last summer running on webers not the triumph ITBs

vacuum advance? there is none. I havent enabled MAP in the haltech and its running distributorless

later on throughout the day I ended up coming across your 'pop tune' map I was wondering if you could post up your regular one lol

I ended up redoing it a couple dozen times and ended up here

https://i.imgur.com/LTjXHCc.png


meanwhile it would seem like the innovative DLG-1/LC-2 setup I was using for wideband finally **** the bed - which is good because Ive been fighting that POS for like 3 years now - like everyone else on the web I highly recommend not buying innovative stuff. just ordered haltechs dual channel CAN based WBO2 controller so will have to wait to get that wired-in in a couple days now....

The comment about vacuum advance is simple. When the TPS signal is low, you have vacuum. At low TPS you have higher timing advance than at high (more open) TPS.

You need to spend some time scaling. I admit I am confused by all the maps you have posted - which one are you using? One shows RPM to 10K and Load to 260 (Load%) You are never going to get there so, don't put them in the table.

You will also get better results if you scale the TPS rows for your ITBs. You are going to want single digit steps to 5, then 2 digit steps to 12ish and then 5% steps, etc. The point is, you will need the resolution at low throttle openings. I typically see <4% TPS readings at cruise RPMs so your ECU is going to blend the throttle closed 0 with the 5% first row. Once the throttle is >30% open there is diminishing returns so you can go large steps to 100% (WOT).

What you propose will certainly get the engine running but like Jamie said above you have much to gain by using more appropriate scaling at small throttle openings.

I think you need to pull a fair bit of timing out of the higher load/higher throttle opening area to avoid detonation given your compression ratio, cam and likely fuel.

As long as you run the engine with the likelihood of detonation in mind you'll be fine until you can get it to a dyno and start fine tuning with importantly some means to monitor knock while you go.

Exciting stage! Good luck!

For reference, the mid ‘80’s 930s ran at maximum 28 or 30 degrees and that is with much lower compression.
Johan

Having your ignition timing jump around will cause drivebility issues.

I'd start with a simple ignition map to get started and then expand it once you get the fueling dialed in. I don't know what a good start point it, but it'd look something like:

<1500 RPM: 10*
2000 RPM: 15*
3000+ RPM: 22*

Make it a 2D table (i.e. same timing as all throttle openings). You'll be simulating an engine with a simple distributor without vacuum advance.

Then look at your logs, and see what throttle openings you tend to use and start expanding your ignition map breakpoints to match what you're driving and experiencing. And start diddling.

Once your AFR is good, you can plot TPS vs RPM vs Pulsewidth to get an idea of cylinder filling.
20% throttle opening at 2000 RPM is the same amount of fuel/air in the cylinder as 100% throttle opening. So you want the same ignition timing at 2000 RPM for anything over ~20% throttle. The same doesn't hold true at higher engine speeds. Pulsewidth should give you an indication of where you can start changing ignition timing.

thank you - this is a great starting spot for me - working on tables today - got my haltech CAN dual WBO2 installed last night after my innovative stuff crapped (add my voice to the collective opinion that theyre garbage - I fought with it for 3 years) and will try and start it again tonight