tuning programmable engine management systems

[Sunriseinla]

My experience is that the 10% ethanol makes the mixture approx. 3% leaner. I looked at the O2 adaptation values on a "modern" car (with and without ethanol).

My next step is to find what influence the pipe has. Because the motronic is actually measuring the air volume, I didn't think this would make such a difference (except at WOT of course).

[scarceller]

Even at WOT the AFM signal is used to calculate mixture till about 5200RPMs where the AFM is maxed out, after 5200RPM at WOT mixture is calculated based on RPM. It's a myth that's been going around for some time that AFM signal is not used at WOT. I know because I have dis-assembled the program code and can clearly see the AFM involved even at WOT.

Typically, you only need to set your base mixture with the Ethanol blended fuels and these cars run fine.

Originally Posted by Sunriseinla

My experience is that the 10% ethanol makes the mixture approx. 3% leaner. I looked at the O2 adaptation values on a "modern" car (with and without ethanol).

My next step is to find what influence the pipe has. Because the motronic is actually measuring the air volume, I didn't think this would make such a difference (except at WOT of course).

[Sunriseinla]

I could tell by the rpm values in the WOT fuel table that somewhere in the 5000rpm region the values from AFM are not used. It's good to know that someone has actually verified this by looking into the code. Do you have any documentation regarding the code that a non software guy can understand? In what region in the map do you think I will mainly need look at to compensate for the pipe? Can I simply disconnect the O2 sensor when I start calibrating the fuel map or is it better to load a euro bin and fill it with my modified US maps? Great thread...Thanks!

[scarceller]

No need to change bins. Simply unplug the O2 sensor and do ALL tuning with it unplugged. You MUST have a WBO2 system to monitor AFR. The system also needs to be able to log at least AFR vs RPM. Then simply pull a WOT run in 2nd gear. For the first few runs concentrate on the 2000-5500RPM range no need to push past 5500RPMs. Then add or remove fuel in the correct places in the WOT Fuel Map to you achieve 13.0AFR across the RPM range. In the stock configuration these cars run very rich at WOT down in the 12.5AFR! Factory did this as safety margin, but these cars really like the 12.8 to 13.2AFR range at WOT.

Then you can also adjust your WOT Ign timing as well but I don't advice doing this till you really know what your doing.

Is this a US or EURO engine? What grade fuel do you run? 93 octane?

I really can't tell you what the effects of the by-pass pipe are, best way is to simply pull the WOT run and look at the AFR curve against RPMs you will then instantly see at what RPMs you are lean or rich and target 13.0AFR across the board.

Next, I'll tell you it's fine to tune the WOT fuel and ignition but this is not where you typically run on the street. I really found the best results by tuning the PartThrottle ignition and fuel. But to do this it must be done on a load dyno cell by cell. I'll only say that the factory PT ignition is far from optimal! It does not generate best torque for most cells, especially the first 4 lo-load rows of the table. I'm not sure why the factory did this? Tuning the car in the PT tables really wakes these cars up! Throttle response is much better and lo-end torque also increases.

PM me if you have more questions.

Originally Posted by Sunriseinla

I could tell by the rpm values in the WOT fuel table that somewhere in the 5000rpm region the values from AFM are not used. It's good to know that someone has actually verified this by looking into the code. Do you have any documentation regarding the code that a non software guy can understand? In what region in the map do you think I will mainly need look at to compensate for the pipe? Can I simply disconnect the O2 sensor when I start calibrating the fuel map or is it better to load a euro bin and fill it with my modified US maps? Great thread...Thanks!

[erwan914]

hello

Sorry for my English

I am French, I have a Porsche 914/6

engine 3.2 USA
CR 9.5
SSi headers Ø43mm
camshaft porsche 964 3.6 timing 1.26mm
megasquirt II V3

which table ignition do you recommend?

picture of my 914


thank's erwan

[erwan914]

up ??

[scarceller]

Erwan,

Single spark plug or twin plug?
If single plug I'd start with the 84-89 3.2L ignition table.
If dual plug I'd use the 964 ignition.

These of course are just safe starting points.

Originally Posted by erwan914

up ??

[erwan914]

Erwan,

Single spark plug or twin plug?
If single plug I'd start with the 84-89 3.2L ignition table.
If dual plug I'd use the 964 ignition.

These of course are just safe starting points.


hello

single spark (EDIS6)

89 tables are up 58% on the Megasquirt is written 100%

58% = 100%?

I begun with programmable injection

thank's erwan





example table Megasquirt

[erwan914]

hello

single spark (EDIS6)

89 tables are up 58% on the Megasquirt is written 100%

58% = 100%?

I begun with programmable injection

thank's erwan

[scarceller]

erwan,

without going into great details yes 58% = 100%

But better yet use the WOT ignition map as the 100% load in MSII table.

Originally Posted by erwan914

hello

single spark (EDIS6)

89 tables are up 58% on the Megasquirt is written 100%

58% = 100%?

I begun with programmable injection

thank's erwan

[scarceller]

Running 34deg ign at 5400RPM could have you in danger zone. If you have not determined those ign values on a load dyno you may want to back off and not exceed 30degrees.

Also do NOT assume the stock 3.2L ign table is tuned to achieve max cyl pressure in Part Load conditions. The factory PT table is far from optimal cyl pressure / torque tune.

I think if you back off to 30 deg max at full 100% load you'll be safe. Then get some dyno time on a load dyno and tune in the PT table.

[erwan914]

hello

the table above was an example

here is the table that I put in the Megasquirt. this is a good starting point ?

[Lorenfb]

"Also do NOT assume the stock 3.2L ign table is tuned to achieve max cyl pressure in Part Load conditions. The factory PT table is far from optimal cyl pressure / torque tune."

Really, and what do you base this on? You've done dyno runs using knock sensors in a
controlled temperature environment to fully evaluate what the maximum and save
timing should be for an engine management system without knock control,
e.g. 911 3.2, right? Porsche with its knock control ECMs, e.g. 928/964/993,
retards the timing up to nine degrees from their idea 'tuning' to protect the
engine from detonation which is NOT possible after 'tuning' a 911 3.2.
Read here for more info: http://www.systemsc.com/tests.htm

Bottom line: It doesn't take any great 'tuning' effort to effect performance,
as it's simple engine basics that a one degree change in timing will result
in a four HP change at the mid to upper RPM range, but will it be safe is the
real issue? As has been said before, 'tuning' is a joke!

[scarceller]

Loren,

I removed my initial post, it adds no value to this thread. Not worth the time to respond or read.

Thanks.

Originally Posted by Lorenfb

"Also do NOT assume the stock 3.2L ign table is tuned to achieve max cyl pressure in Part Load conditions. The factory PT table is far from optimal cyl pressure / torque tune."

Really, and what do you base this on? You've done dyno runs using knock sensors in a
controlled temperature environment to fully evaluate what the maximum and save
timing should be for an engine management system without knock control,
e.g. 911 3.2, right?

Bottom line: It doesn't take any great 'tuning' effort to effect performance,
as it's simple engine basics that a one degree change in timing will result
in a four HP change at the mid to upper RPM range, but will it be safe is the
real issue? As has been said before, 'tuning' is a joke!

[drmatera]

some good fundamental info here. can we keep this thread on topic? i would like to hear more on tuning theory than "whats the best a/f for my car?" getting a tune that makes a good driving/running car is more than a/f targets

Thanks

[safe]

Just get on a dyno runned by a competent operator.

[erwan914]

thank you for your help, sorry for my english

if I understand well the table 89 is not the best to start?

at:Tests


WOT = maximum load ?

why the charge stops at 60%

after your comment I made this table, when do you?


@+ erwan

[Tippy]

Originally Posted by scarceller

Loren,

I removed my initial post, it adds no value to this thread. Not worth the time to respond or read.

Thanks.

I think your original response was fine.

That said, keep up the good work! Your knowledge of Motronic tuning is in the big leagues.

[scarceller]

Erwan,

This is a much better starting point for ignition.

As for your question on the load axis being 58% all I'll say is stop trusting the axis the Motronic load axis is NOT load! The folks who built the motronic editor did a fine job at the time but did not really understand how that load axis works and is selected by the software. I have a lot of time invested in my research and don't plan to disclose every detail as some of my finding will go into a product very soon. I will say that you should simply treat the last 58% row as very hi-load like 90% or 90KPA on the map sensor.

I also sent you a PM did you get it?

Originally Posted by erwan914

thank you for your help, sorry for my english

if I understand well the table 89 is not the best to start?

at:Tests


WOT = maximum load ?

why the charge stops at 60%

after your comment I made this table, when do you?


@+ erwan

[erwan914]

position sensor BMW 320I



picture my engine