Slow revving? Manual car.

[jedibow]

Originally Posted by wu_dot_com

here is what i think its happening.

the ECU control the engine performance by adjusting the fuel input and monitor the output shaft RPM. for reach RPM range change, the time duration from one state to another is also tracked. from my understanding, the ECU does not track the actual load output. the data for the fuel map are generated empirically from the running the engine at different throttle condition with OEM components.

That used to be true, however there are infact two load variables present in this ECU, Load calculated (which is what I believe you are refering to as it takes into account TPS, barometric pressure, IPW, and injector scaling) and correct this is used to determine the lookup cell in the fuel map, the second load variable is "absolute load" which is also an internal calculation within the Ecu, however it is used to determine the lookup cell on the ignition map. AFAIK RPM delta does not factor into this calculation, however I may be incorrect.

Originally Posted by wu_dot_com

now a lighter flywheel will give a higher angular acceleration. which means for the same input, the output shaft RPM will be higher with a lighter flywheel.

I already explained this, the ecu will trace faster across the map, but it will not redefine the actual axis values...

Originally Posted by wu_dot_com

now i will try to describe what ive experience with the light weight flywheel. i will use some fabricated numbers to help the understanding since i cant graph it for you.

Originally Posted by wu_dot_com

so lets just say for this car, the idle RPM is at 800 with throttle setting of 8. if we want to increase the RPM to 1K, the throttle setting will be 10, if we want to reduce the RPM to 500, the throttle setting will be 5. in a car, the data in this fuel map are all empirically gather based on OEM hardware. if you want a graph, the X axis will be your RPM, and your Y axis will be your throttle. you can drawing a expediential line and call it your OEM baseline. now with a light flywheel, when your throttle setting is at 8, your actual flywheel RPM will be at 1k because you lessen the rotational mass and inertia. on the same graph, you now will draw a second expediential line from 0, 0 but the line will be to the left of the original OEM baseline. this new line will be your delta, however, this line is unknown to the ECU.

now to achieve idle, your ECU is going to give a throttle command of 8, while expecting to get a feedback of 800 RPM. however, the output shaft output shows an RPM of 1K. so the ECU feedback loop now think your actual throttle response is actually at 10, and it compensated by reduce it down to 5 to quickly bring the RPM back down to 800. since the lightweight flywheel dissipate the store energy much faster, at throttle input of 5, the actual RPM is 400 RPM. at that moment, the ECU will recognizes the engine is now too slow, and increase the throttle back to 10 in an attempt to bring up the rpm quickly.

Are you refering to IDLE step control??? I never said that the Idle would not have to be adjusted I completely agree with you, however we are not sure whether the Ecu uses fuel to control Idle speed, or timing yet... And yes you are also correct the Idle speed delta tables will have to be tuned, however it is my experience (running an exedy twin plate, yes it has a lighter flywheel) that I pulled a single step out of the correction factor at the larger delta values, and it Idles A okay!

Originally Posted by wu_dot_com

this is what i've experience so far with my prototype flywheel. i hope my attempted at discribing what happened makes sense.

The broad statement of "tuning" is what confused me, I hope I was able to clarify for people that are not in the know. Again I completely agree that it may be necessary to tune the Idle stepper look up tables, or delta correction tables in order to restore a proper (no loping) Idle. However we will still need to identify in the Ecu how Subaru adjusts the idle, does it alter fuel (IPW) or does it alter ignition timing?

[wu_dot_com]

Originally Posted by uspspro

So are you getting a surging, or lightly oscillating idle?

yap.

my current flywheel will oscillate at idle from 800rpm to 500rpm (surge) in standard day condition (70-90°F), light humidity.

dont know the performance in hot (T>90°F) or cold (T<70°F) at the moment.

[wu_dot_com]

Originally Posted by jedibow

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That used to be true, however there are infact two load variables present in this ECU, Load calculated (which is what I believe you are refering to as it takes into account TPS, barometric pressure, IPW, and injector scaling) and correct this is used to determine the lookup cell in the fuel map, the second load variable is "absolute load" which is also an internal calculation within the Ecu, however it is used to determine the lookup cell on the ignition map. AFAIK RPM delta does not factor into this calculation, however I may be incorrect.



I already explained this, the ecu will trace faster across the map, but it will not redefine the actual axis values...



Are you refering to IDLE step control??? I never said that the Idle would not have to be adjusted I completely agree with you, however we are not sure whether the Ecu uses fuel to control Idle speed, or timing yet... And yes you are also correct the Idle speed delta tables will have to be tuned, however it is my experience (running an exedy twin plate, yes it has a lighter flywheel) that I pulled a single step out of the correction factor at the larger delta values, and it Idles A okay!

[COLOR=black][FONT=Verdana]

The broad statement of "tuning" is what confused me, I hope I was able to clarify for people that are not in the know. Again I completely agree that it may be necessary to tune the Idle stepper look up tables, or delta correction tables in order to restore a proper (no loping) Idle. However we will still need to identify in the Ecu how Subaru adjusts the idle, does it alter fuel (IPW) or does it alter ignition timing?

i agreed with you 100%, at the moment, i need to get in contact with Cobb, since they have the capability to do ECU flash retune to see what they can do.

[Symbiont]

Originally Posted by wu_dot_com

i agreed with you 100%, at the moment, i need to get in contact with Cobb, since they have the capability to do ECU flash retune to see what they can do.

Wait... Are you sure? I talked to them a week ago and they didn't seem so sure they'd have any tuning on the BRZ for quite awhile.

[jedibow]

Originally Posted by wu_dot_com

yap.

my current flywheel will oscillate at idle from 800rpm to 500rpm (surge) in standard day condition (70-90°F), light humidity.

dont know the performance in hot (T>90°F) or cold (T<70°F) at the moment.

That amount of difference leads me believe that the Ecu is using ignition timing to adjust the idle speed. Do you have the option to datalog? PM me if you are interested. I would like to see logs if ignition timing, and LTFT-low.

G

[jedibow]

Originally Posted by wu_dot_com

i agreed with you 100%, at the moment, i need to get in contact with Cobb, since they have the capability to do ECU flash retune to see what they can do.

Actually they do not, they are still working on defining the ROM, contact John Visconti (member name Visconti) from V tuned here on the board.

G

[Symbiont]

According to the gentleman I spoke with at Cobb, he estimated that Cobb wouldn't have an Accessport for another year, if at all.

[jedibow]

Originally Posted by Symbiont

According to the gentleman I spoke with at Cobb, he estimated that Cobb wouldn't have an Accessport for another year, if at all.

No they are definiately working on it

[Symbiont]

Originally Posted by jedibow

No they are definiately working on it

Oh, I know; the Austin location has a BRZ.

I also know what the Sales/CS rep told me about it as far as their current ETA.

[jedibow]

Originally Posted by Symbiont

Oh, I know; the Austin location has a BRZ.

I also know what the Sales/CS rep told me about it as far as their current ETA.

I know who they have working on it, and I wouldn't be surprised at all if we see it by christmas

[wu_dot_com]

Originally Posted by jedibow

That amount of difference leads me believe that the Ecu is using ignition timing to adjust the idle speed. Do you have the option to datalog? PM me if you are interested. I would like to see logs if ignition timing, and LTFT-low.

G

at the moment, i dont have any data loging device hook up. but i am willing to hook it up if someone can show me how (or help me get the equipments to do so)

Originally Posted by jedibow

Actually they do not, they are still working on defining the ROM, contact John Visconti (member name Visconti) from V tuned here on the board.

ya i dont know if Cobb have anything yet. but i know they are working on something. since i am in LA area, and they are very close to me, thats why their name poped into my head. i just thought this will be something interesting for them to take a look at. since i dont think there is a lot of BRZ owners have a light weight flywheel installed at this moment.

G

Originally Posted by Symbiont

According to the gentleman I spoke with at Cobb, he estimated that Cobb wouldn't have an Accessport for another year, if at all.

do you have a contact for their TX outfit or here in LA? the person that ive contacted are here in CA his name is Ronnie.

[Symbiont]

Originally Posted by wu_dot_com

do you have a contact for their TX outfit or here in LA? the person that ive contacted are here in CA his name is Ronnie.

Yeah, Ronnie is in Sales/Customer Service. Any info you're going to get is going to be out of Austin, right now, and I haven't been able to get a response.

[jedibow]

Originally Posted by wu_dot_com

at the moment, i dont have any data loging device hook up. but i am willing to hook it up if someone can show me how (or help me get the equipments to do so)





do you have a contact for their TX outfit or here in LA? the person that ive contacted are here in CA his name is Ronnie.

Please PM me and I will answer both...

G