PI : DI Ratio Discussion

[KoolBRZ]

Is that actual AFR, or is it the requested AFR from the ECU? If it is requested AFR, mine is doing the same thing. If actual AFR is too rich, then the requested AFR goes lean to pull it back to where it needs to be. The actual AFR is what we need to concentrate on, Especially in Open Loop.

[solidONE]

Originally Posted by steve99

After a couple of tests settled on ratios as below. Made the 3200 line 100% DI as this is arround where the last ltft correction is done (maf arround 3V) and after that your using DI exclusively anyway

Needed to adjust the Port Injector BRZ scalar down 3% to balance up the PI with DI.

Now getting pretty well 0 ltft (+/- 1%) except for the first couple near idle about 3% variation with large changes in intake air temps.

After running a slightly modified version of the port injection ratio table(0% in .20 loads) with 5% lower value on the port injector scalar, my fuel trims are still a bit high at the .30~.40 areas where its' running 70% port. Though this is on my new maf scale that was dialed to 68*f/20*c. I've decreased the value to -6% lower than the stock value and will see if that fuel trims will go down a bit more.

[solidONE]

Originally Posted by Kodename47

If it's only just during cruising then I'd leave it, better fuel economy and all that. Your actual AFR doesn't quite go that lean anyway. I haven't seen that on mine though so I'm not sure why it's happening especially as in CL is should be targeting 14.7.

His low load cruising AFR's are averaging 15.6:1 and can go higher than 16.0:1 in spots, are you sure that's okay?
http://www.datazap.me/u/yobiwan/sc11...zoom=4991-5146

[KoolBRZ]

Originally Posted by steve99

After a couple of tests settled on ratios as below. Made the 3200 line 100% DI as this is arround where the last ltft correction is done (maf arround 3V) and after that your using DI exclusively anyway

Needed to adjust the Port Injector BRZ scalar down 3% to balance up the PI with DI.

Now getting pretty well 0 ltft (+/- 1%) except for the first couple near idle about 3% variation with large changes in intake air temps.

I finally found the Injector Scaling BRZ table, and decided to give your changes a try. I think you have the right idea. It is running rich in CL with increased PFI, so scale back the PFI Pressure to compensate. I'll give that, and your revised PFI to DI table a try today.

[Kodename47]

Originally Posted by solidONE

His low load cruising AFR's are averaging 15.6:1 and can go higher than 16.0:1 in spots, are you sure that's okay?
http://www.datazap.me/u/yobiwan/sc11...zoom=4991-5146

Yeah, quite a few engines run 15-16:1 in closed loop, Honda do to name one.

Originally Posted by KoolBRZ

I finally found the Injector Scaling BRZ table, and decided to give your changes a try. I think you have the right idea. It is running rich in CL with increased PFI, so scale back the PFI Pressure to compensate. I'll give that, and your revised PFI to DI table a try today.

Just so you're aware, decreasing the injector scalar will make you run richer.

[ztan]

Originally Posted by Yobiwan

I logged after changing PI/DI ratio.

http://www.datazap.me/u/yobiwan/sc11...zoom=4683-5433

CL AFR target become leaner. always shows 15~16

today I switched to original PI/DI table . and CL AFR is steady on 14.7


HKS V2 supercharger with 41.5mm restrictor
Tomei UEL header
Stock intake with KN filter
OFT tune.

I agree with solidONE. Something is not right. mad_sb and others have tried to force lean cruise and not been able to. I wonder if your table defs or logging address for target AFR are right. What ECU Calibration ID are you running and where are you logging target AFR from; what is your stock ROM?

Would be interested to see your ROM and defs.

[KoolBRZ]

Originally Posted by Kodename47

Just so you're aware, decreasing the injector scalar will make you run richer.

How right you are. I experienced the 1-2 punch of lower MPG AND less horsepower this morning. The less horsepower was particularly disappointing. I loaded a previous tune, and I'm back in business.
So, making the AFR richer with Port Injector scaling will end up making Open Loop leaner, correct? Ideally I want a Closed loop AFR of 14.7, so that Open Loop will be just right.

[Yobiwan]

Originally Posted by ztan

I agree with solidONE. Something is not right. mad_sb and others have tried to force lean cruise and not been able to. I wonder if your table defs or logging address for target AFR are right. What ECU Calibration ID are you running and where are you logging target AFR from; what is your stock ROM?

Would be interested to see your ROM and defs.

A01E (S. Korea 6MT)
and logged from OFT

HKS sc
removed stock 2nd o2 sensor, using AEM UEGO wideband now.

and AEM wideband shows 15.6 AFR too.

but I changed back to stock PI/DI table and everything is fine now.

I'll send my roms & def to you.

[freerunner]

Originally Posted by KoolBRZ

So, making the AFR richer with Port Injector scaling will end up making Open Loop leaner, correct? Ideally I want a Closed loop AFR of 14.7, so that Open Loop will be just right.

Yes. We don't want corrections from CL applied in OL in this case. Assuming our MAF scale was done properly before we changed our di:pi ratio table.

[solidONE]

Originally Posted by Kodename47

Yeah, quite a few engines run 15-16:1 in closed loop, Honda do to name one.

I'm aware engines designed for lean burning, question is can this engine handle it specially since this engine has a history of burning DI seals. I suppose if he was running E85 then this would actually be closer to ideal and the engine wouldn't have as much trouble with possible problems associated with running this lean. Not so sure about doing this with petrol.

[Kodename47]

Originally Posted by solidONE

I'm aware engines designed for lean burning, question is can this engine handle it specially since this engine has a history of burning DI seals. I suppose if he was running E85 then this would actually be closer to ideal and the engine wouldn't have as much trouble with possible problems associated with running this lean. Not so sure about doing this with petrol.

Lean burning at low loads I can't imagine being an issue, I doubt that the energy produced would be enough to cause any issues, especially as we're talking less than 10% off stoich.

[thambu19]

Originally Posted by Kodename47

If it's only just during cruising then I'd leave it, better fuel economy and all that. Your actual AFR doesn't quite go that lean anyway. I haven't seen that on mine though so I'm not sure why it's happening especially as in CL is should be targeting 14.7.

Why 14.7 when stoich for e10 is 13.9? 14.7 is for e0 which isn't available anymore.

Sent from my HTC One_M8 using Tapatalk

[jvincent]

Originally Posted by thambu19

Why 14.7 when stoich for e10 is 13.9? 14.7 is for e0 which isn't available anymore.

Plenty of e0 up here.

[solidONE]

Originally Posted by Kodename47

Lean burning at low loads I can't imagine being an issue, I doubt that the energy produced would be enough to cause any issues, especially as we're talking less than 10% off stoich.

I guess a boosted setup with the extra heat would be a good type of stress test of running leaner at low loads on petrol. If someone (ahem) wants to be the guinea pig, we may or may not have stumbled upon a method to achieve a lean burn. I surely wouldn't mind trying this out on my E85 rom. I'll volunteer myself for that once ztan or the rest of you programmer types work your magic.