Wanted: 3.6 Twinplug Timing Map

[LeftCoastErik]

I am fighting some weirdness in my map on MS. But does anyone have a good working twinplug timing map I can check out? I haver included mine for comparison. Thanks!

[LeftCoastErik]

d

[LeftCoastErik]

again

[jpnovak]

Erik,

What kind of problems are you having? Here are some of my observations.

Way too much timing at low rpm and higher load. With ITBs I assume you are idling in this area. Might be hard to start and idle high with those numbers.

IN general, the low load sites typically have more advance than high load. This is because there is less air to burn and you have to ignite earlier in the combustion cycles.

The sudden jump in timing to 7K could be a concern.

You should start with the stock 964 timing curve and then optimize from there. This is the 1995 993 curve from my files. Thanks to Sal Carceller for decoding.

You can see load on Y axis. Add idle timing row based on your idle MAP value. Add WOT throttle to the top. Fill in the middle and blend.

[LeftCoastErik]

Thanks Jamie. The car starts and idles really well, actually. The issues I have are at low TPS/Load cruising where I get what sounds like a misfire. Tipping in makes it go away. Its fine when you are in it, but at cruise its annoying. So 2200-3200 rpm is where its most noticeable. I could never get the car to be smooth with the ITB blend, so the tune is currently setup on Alpha-N

[LeftCoastErik]

OK, let me play with that. Can I translate the load% to TPS % from that map?

[jpnovak]

You have some steep jumps in timing in the lower left corner. My guess is that the ECU is trying to interpolate across this steep section and you feel that as a misfire/surge oscillation. Its the downslope where the ECU pulls timing in the calculation that you feel the most.

A datalog will probably show a timing oscillation at this location. Find it and adjust timing until it goes away. The TPS/RPM bin locations will not change. But the timing value in them must change to take out the oscillation.

I would start with less than 13% is equal to your TPS load. Then double the load to equal your TPS from there up. You will likely have a hole in the 22=35% range. Use the smooth function to blend across this empty row.

This will get you started. email me a tune file and datalog of the issue and I can help smooth it.

[LeftCoastErik]

well, true to your sig, you just explained to me, but I don't fully understand what you are talking about regarding the "13% equal to my TPS load"

[jpnovak]

Ha! Sorry. My mental table scaling took over.

Check your email. That should make sense.

[LeftCoastErik]

Lol, thank you the visual certainly helps me get where you were going. The scaling was what I was perplexed with too. Makes more sense now as it was idling in the bottom corner anyway. I will go load this up and see how she does! Thanks again Jamie!

[al lkosmal]

Erik,
Here's an ignition map from a good, running 3.6.........the ECU is a AEM Infinity and Map/RPM is used for the ignition map ....and really worked very well. Your results may vary. As Jamie points out, you have some very abrupt timing changes......you might try just applying the smoothing function to your current map out to see if there is an improvement.




regards,
al

[pampadori]

I don't know how a twin plug responds since I only have my own experience which is with a 3.0 single plug. However, I'll tell you what worked for me and you can apply it to your setup if you want, at your own risk of course.

I run my light throttle target afr at 14.7:1. I am running mid 40's ignition timing by 3000 rpm. I go as high as 50° at the upper rpms at light throttle loads. Running that much timing at light throttle makes the engine feel very torquey and let's you run lean afr to get really good fuel mileage.

The risks aren't as high at low loads if you do have some pinging. Cyl pressures are lower and the force on the ring lands isn't as great. you can use your ears more to tune without as much fear of blowing up your motor.
I can't hear my motor ping when I have my dynomax setup installed. It's just too loud to hear it. So i swap my BBE muffler back on and drive with the windows down next to a picket fence to mess with my ignition timing. I can actually hear it ping when it's 95f out and I'm running too much part throttle ign timing. I take a couple of degrees out and might add a smidge more fuel or target a slightly richer afr and it goes away. The noise to listen for is subtle but you can definitely hear it if conditions are right. It's always best to use a knock sensor of course but a good ear and a quieter muffler will work.

If you treat WOT, 50% throttle, and 25% and less throttle as three different things, you can start to get some nice results.

Search for a thread titled something like "official ignition timing map sharing thread" on here and you'll find a discussion that has a bunch of folk's ign maps that you can compare against. But again, twin plug changes things and I'm pretty sure it requires you to turn less advance than single plug so be cautious of that.

[Raceboy]

Twin plug requires very low advance values at idle and off-idle areas. 1-3 degrees is good value, there is absolutely no need to advance it further, it will make idle quality (observed by how strong vacuum it pulls is good measure) good and strong and also exhaust burns clean.
All easily observable when using 5gas analyser.

[JohnJL]

Originally Posted by al lkosmal

Erik,
Here's an ignition map from a good, running 3.6.........the ECU is a AEM Infinity and Map/RPM is used for the ignition map ....and really worked very well. Your results may vary. As Jamie points out, you have some very abrupt timing changes......you might try just applying the smoothing function to your current map out to see if there is an improvement.




regards,
al

Is it normal practice to have fuel load Alpha-N (TPS) and ignition Speed Density (MAP)? Early on I paid for a couple of guys to remotely tune and I am not sure they meant to leave it like that...

I interpolated Al's map into megasquirt here...will try later or tomorrow...

[JohnJL]

How can I post up files for sharing?

Jamie, do you use use TPS for fuel and spark, or just spark? Do you have that 993 map in a Tunerstudio-importable file?

[LeftCoastErik]

Thanks I’ve subsequently reworked the table using the 993RS map and it’s pretty similar and does work well.

[JohnJL]

I have a surging idle that has stumped me and 3 "pro" tuners. It seems ignition-related but has me starting fresh to try and straighten it out now that its on the road every dry night and early morning I can escape..

[Joesmallwood]

Following. Is there an update to this thread? I am also looking for a reference ignition table for a twin plug 3.6 liter running 10.5 CR. If possible, I would like to find a reference AFR table as well.

[lvporschepilot]

Has anyone noticed if larger barrel twin plug 3.6L engines run more or less timing at WoT than smaller bore engines? Theoretically, because smaller bore engines have less distance for both flame fronts to travel, I would think a 90mm bore twin plug engine running 10.5:1 would want less timing than a significantly larger bore engine running a similar twin plug arrangement. Dome shape and size probably plays into this as well of course. Splitting hairs I know....