EFI tuning with MS3X – ignition table

[billjam]

I have been concentrating on getting my fuel table sorted out and now that the engine runs well and pulls really strongly, I feel that I should start looking more closely at the ignition tables.
I received tables, tune files and advice from several Pelicans over the past couple of months and I used a combination of these as a basis for my current ignition table below.
There is a great thread in the Turbo forum which includes lots of ignition maps and info for turbos, but I haven’t been able to find a collection of similar info for n/a cars.
Does this table look OK?
Without doing time on a dyno, is there a way to optimise ignition timing?



Engine is 3.6 with MS3X, ITBs, sequential COP ignition, sequential injection and DC21 cams.

[cmonref]

BillJam,

Timing at 1000 should be not more than 10 degrees -- probably closer to 5 degrees. At 500, it should be about +4 from what is in the 1000 RPM column.

Looking at the timing table above and the VE table in your other post, I can't figure out where your idle is. The timing table has really fine gradations on the load axis as opposed to gradations on the VE table. What is your idle load?

On my 1980 911SC, idle timing is 5 degrees and idle was quite smooth with equal VE table values around idle. Idle MAP is 42-45 kpa, and with MAF it is around 22% MAFload.

It is perplexing that your timing load axis has 11 of 16 values less than the MAF load I see. I know you are using ITBs, but I had always thought that MAP or load values were much higher than with SD or MAF.

Brian

[billjam]

Originally Posted by cmonref

Timing at 1000 should be not more than 10 degrees -- probably closer to 5 degrees. At 500, it should be about +4 from what is in the 1000 RPM column.

I dropped the timing to 5* at 1000, but forgot to bump it up for 500rpm! Idle isn't a problem, but I'll deal with that minor change next time.

Originally Posted by cmonref

Looking at the timing table above and the VE table in your other post, I can't figure out where your idle is. The timing table has really fine gradations on the load axis as opposed to gradations on the VE table. What is your idle load?

Idle load is around 50% and 800rpm.
I'm not sure why the Load axis values are so close together at the bottom of the range as they always used to be more evenly spread. I must have screwed that up when I was editing tables recently, so I have reset those axis values based on a previous table.
I have also retarded the zone where exhaust popping is a problem, but it hasn't fixed it yet.

I would be very interested in seeing ignition tables for other 3.6's.
Also, original question remains ... Without doing time on a dyno, is there a way to optimise ignition timing?

[cmonref]

Finished a response, pressed SEND, and the computer quit. Grrrrr! Here we go again!

The ignition table should have maybe 3 load values below idle, down to the minimum that the engine will see. You have 8 values, down to 0. The difference of 5 values would allow you to put points above 50% load with less spread.

Here is the Motronic advance table for a 993. Watch out for reverse y axis (why would the axis go from high to low going up on the axis??). 5000 RPM is tops on this chart -- somehow the higher values got truncated when I copied it -- but the values were not any different above 5000, Scarcellar reported this chart and said that ~10% is idle and ~16% is highway cruise (BUT --- he may have been talking about values on his 3.2L Motronic, but they look about right on THIS chart to me.)



See also the Steve Wong website -- he has a GREAT article on timing from the 3.2L to 3.6 (964 and 993.)

911Chips.com - Porsche Performance Chip Tuning

I don't think the ignition table has anything to do with the exhaust popping -- it is in the VE table, I am sure. You can set your timing back where is was before, or use the 993 model above to tweek it some.

I set my advance table as a model of the OEM 1980 911SC (ROW) distributor -- it is described in your other thread. You might do the same with the 993 table above.

Regarding timing table adjustments NOT on a dyno, Scarcellar wrote a little ditty on Pelican about "level road with a buddy" testing. With the buddy driving and you with your laptop, drive at a stead speed then adjust the advance until the RPM maxs out. Then change speeds and do it again. Search on Scarcellar on Pelican, and on psalt, jpnovak, and others, who all offer a wealth of information about timing on non-Turbo cars.

Brian