Getting Best MPG during Cruise - Page 9

UT_EvoX · Nov 4, 2009, 10:56 AM

Quote:

Originally Posted by Clipse3GT

I am not so sure.... Then why is each Fuel Cylinder map the same 14.7 and adjustable. I think these map may adjust closed loop fuel trim. I will try to test this with a stock IGN map and see if what my closed loop looks like.

I dunno... makes sense to me. Otherwise what is the point of those tables...

Ah, that makes perfect sense. Doesn't change the target AFR, but does change the resulting STFT. I'll test it out as well.

What about them affecting open loop? I know it doesn't matter where you've adjusted the map, but it's something to investigate.

Clipse3GT · Nov 4, 2009, 02:14 PM

Quote:

Originally Posted by UT_EvoX

Ah, that makes perfect sense. Doesn't change the target AFR, but does change the resulting STFT. I'll test it out as well.

What about them affecting open loop? I know it doesn't matter where you've adjusted the map, but it's something to investigate.

Yeah I think it would be interesting to see what happens... when you change the fuel trim only. I will hopefully test it out today.

See if there is a difference, at the worst it just won't work. LOL

LaXGSR · Nov 4, 2009, 02:30 PM

Quote:

Originally Posted by Clipse3GT

Yeah I think it would be interesting to see what happens... when you change the fuel trim only. I will hopefully test it out today.

See if there is a difference, at the worst it just won't work. LOL

Thanks for trying this out! Great idea, hope it works! I agree that it seems odd to have these cylinder trim maps with 14.7 in them. I'm also hoping the ECU checks these maps to see what "stoich" should be based on rpm/load during closed loop.

UT_EvoX · Nov 4, 2009, 02:52 PM

Quote:

Originally Posted by Clipse3GT

Yeah I think it would be interesting to see what happens... when you change the fuel trim only. I will hopefully test it out today.

See if there is a difference, at the worst it just won't work. LOL

When I first saw those tables, I figured they were just to fine-tune the fuel mixture on a per-cylinder basis. Especially for WOT operation. I have the same functionality on my e-Manage Ultimate.

Maybe it's as you've described it, though. Only one way to find out

Clipse3GT · Nov 4, 2009, 02:56 PM

Quote:

Originally Posted by UT_EvoX

When I first saw those tables, I figured they were just to fine-tune the fuel mixture on a per-cylinder basis. Especially for WOT operation. I have the same functionality on my e-Manage Ultimate.

Maybe it's as you've described it, though. Only one way to find out

Yeah maybe these are the values the ECU looks at will in closed loop... let's hope. That way you can just make the car run in closed loop at cruise (the way cars are designed to do) and just have a leaner closed loop AFR. This was you can leave your High Octane map alone and start messing with the High IGN map...

I hope to get out tonight and see what it does... I doubt I will go into WOT with these settings now. But will check closed loop operation with something like the most efficient AFR which is 15.2... 14.7AFR is best for the CAT.

UT_EvoX · Nov 4, 2009, 03:00 PM

I can check it at idle right now to see if it does anything. Will report back.

Clipse3GT · Nov 4, 2009, 03:09 PM

Quote:

Originally Posted by UT_EvoX

I can check it at idle right now to see if it does anything. Will report back.

Sounds good let us know... should be very apparent at idle... just set all 4 maps in all the fields to about 15.2 AFR... since it will be idling anyways... shouldn't hurt anything and check STFT,LTFT IDLE, and WB AFR.

UT_EvoX · Nov 4, 2009, 03:23 PM

Quote:

Originally Posted by Clipse3GT

Sounds good let us know... should be very apparent at idle... just set all 4 maps in all the fields to about 15.2 AFR... since it will be idling anyways... shouldn't hurt anything and check STFT,LTFT IDLE, and WB AFR.

It's as I suspected. Set to 15.6 at idle and under open loop AFR's were about that lean, but as soon as closed loop kicked in, back to 14.7. STFT before was near 0, after leaning out those 4 tables it was about +4%. Looks like those 4 tables just modify injector pulsewidth and don't affect the effective STFT.

Hmmm... back to the drawing board.

tipoytm · Nov 4, 2009, 03:29 PM

Qq =x

Clipse3GT · Nov 4, 2009, 03:30 PM

Quote:

Originally Posted by UT_EvoX

It's as I suspected. Set to 15.6 at idle and under open loop AFR's were about that lean, but as soon as closed loop kicked in, back to 14.7. STFT before was near 0, after leaning out those 4 tables it was about +4%. Looks like those 4 tables just modify injector pulsewidth and don't affect the effective STFT.

Hmmm... back to the drawing board.

Guess... so...

Thanks for that test.

So as of right now it might be best to set your car into open loop and lean out the cruise AFR regions and ADD timing advance into the cruise region.

tephra · Nov 4, 2009, 04:48 PM

yeah so basically they are just injector pulse width compensators.

assuming that's 100% accurate - they are useful to have.. especially if you know #2 is slightly leaner than all the other cylinders..

but I can see why mitsu left them at 100% (14.7) - just too hard to tune them without sophisticated equipment..

UT_EvoX · Nov 4, 2009, 05:04 PM

Quote:

Originally Posted by tephra

but I can see why mitsu left them at 100% (14.7) - just too hard to tune them without sophisticated equipment..

Such as a wideband in each runner

WBO2 sensor would probably last 10 minutes of WOT hahaha.

tephra · Nov 4, 2009, 05:10 PM

yeah basically.

then you also need to be able to hold the car at certain RPM's and certain loads.

then go through each rpm/load point and create a cylinder trim compensation map.

lots of fun, if I had the resources I would do it - but I dont :P

Clipse3GT · Nov 5, 2009, 03:05 PM

Does anyone know how much of a effect MAF scaling and Injector Scaling have on fuel consumption.

So lets say your MAF scaling is stock and you are running 800cc injectors. However, you have them scaled for 770cc put let say you scale them down to 730cc (a smaller injector) hell even a 696 injector and adjust the latency to compensate for the size of the injector. Would that improve fuel economy?

I am just wondering this...

Then once you run either more boost or a large turbo or cams you can scale the injectors up and adjust the latencies.

tephra · Nov 5, 2009, 03:43 PM

you are really dying for better fuel consumption hey

generally:
1) make more power from the fuel you put in - ie MIVEC or IgnitionAdv changes
2) put less fuel in (ie lean cruise) - but this will require MORE IgntionAdv again otherwise you will loose power from the slower burning mix

I have yet to see any empirical proof that #2 works, feel free to do some tests for us