Is Port Injection more important when boosted?

[BRZoomTX]

Originally Posted by Kodename47

DI gives you charge cooling in cylinder and therefore better knock resistance if you have good mixture. I tend to run higher amounts of DI in transitional areas for this reason. I think this is more what you need to concentrate on than feel. Changing the ratios only and then feeling the difference is no different to just changing the fuel map with no changes to anything else.... it's part of a bigger system, you're being too short sighted. Why not run 100% PI and only use DI when you need, it'd probably feel awesome.

Also, I have posted the thresholds for most of the modern calibrations. It's quite easy to find them on other cals to.

Can't really run 100% PI unless you delete the direct injectors. The direct injectors need at least some fuel flowing through them to keep them cool.

[Xero-Limit]

FYI there are limits that we identified a year or two back that prevent precise targeting of the DI/PI mixture. EcuTek has fixed this a good while back but you may not have access to that on open source or other platforms. You'll be limited to about 35-70% range IIRC if that is the case.

[BRZoomTX]

Originally Posted by moto-mike

FYI there are limits that we identified a year or two back that prevent precise targeting of the DI/PI mixture. EcuTek has fixed this a good while back but you may not have access to that on open source or other platforms. You'll be limited to about 35-70% range IIRC if that is the case.

Ecutek has those limits available for master tuners at the moment, but unfortunately us DIY guys are not able to modify them as they are still "beta" features. DIY w/ the RaceROM upgrade is missing out on that still.

However if I run 100% DI, it uses DI for everything except idle witch will switch over to PI. After a while it does start using DI to idle, so really not sure. It uses PI immediately after a flash but will eventually start using 100% DI idle. I haven't found a way at least with my DIY license to always force 100% DI at idle. Maybe some warm up or undiscovered ECU strategies are messing with it still. I can only really guess.

I wish they would offer a beta opt-in so we can also play around with the newest updates.

Edit-
To clarify, there is a beta feature for the minimum /maximum PI thresholds available in Ecutek, but DIY kit has no access to those. Not sure how much they affect the ratios when using a DIY kit which can't see those features.

[KoolBRZ]

Just not for the reason given in my theory. It is important to supply additional fuel when needed. I'll have to try 100% DI in low load ranges up to .6 to see how it runs.

[Kodename47]

Originally Posted by BRZoomTX

Can't really run 100% PI unless you delete the direct injectors. The direct injectors need at least some fuel flowing through them to keep them cool.

I was aware, I was being sarcastic

Originally Posted by moto-mike

FYI there are limits that we identified a year or two back that prevent precise targeting of the DI/PI mixture. EcuTek has fixed this a good while back but you may not have access to that on open source or other platforms. You'll be limited to about 35-70% range IIRC if that is the case.

These parameters have been in ECUtek since I passed them on but they are not in end user software. These have been defined in Romraider since then too.

[BRZoomTX]

Originally Posted by KoolBRZ

Just not for the reason given in my theory. It is important to supply additional fuel when needed. I'll have to try 100% DI in low load ranges up to .6 to see how it runs.

The ECU calculates the required fueling way before using the DI:PI ratios, so adjusting the ratios is not doing anything other than taking more load off either set of injectors... Such as running more PI ratio to supply enough fuel for higher boost where the DI system tops out. When you increase the PI ratio, you are really just saying "run more fuel off the port injectors so that the direct injectors do not hit their limit, causing a lean condition".

If I recall correctly, 100% DI may be used up to ~250whp (~300bhp). Don't quote me on the exact numbers, but that is mainly why we adjust top-end ratios for more PI fueling. The stock DI system just can't flow that much fuel.

[KoolBRZ]

There are things to be said for 100% DI. There is a stutter, or delay with PI right after a shift. That's gone with 100% DI. On the other hand, there is more low-end torque with PI. One of the tables below has a gradually increasing amount of PI up to 4.0 load. That was the tune I felt more low-end torque with. 100% DI is quicker though, above 3000 rpms.

[KoolBRZ]

I normally drive with the engine cruising between .4 and .6 load, and accelerate between .7 and 1.4 load. I've also noticed bogging after a shift, when it changes from .5 or .6 load to .9 or 1.0 load at the new lower rpm right after a shift. I think this is caused by the delay inherent in PI versus the immediate response of DI. So how about using DI 100% from idle to 2000 rpm, and from .15 to .6 load, then 70% PI dropping down to 20% from 2000 rpms on up, and from .7 through 4.0 load. I'll try out these 2 tables tomorrow and see how well PI does for acceleration only. If this works out, then I'll start adding timing in all the 100% DI sections.

[KoolBRZ]

I've been playing around with straight DI, and for an AT it shifts better and accelerates better. Knowing it is limited in the higher rpms and loads I made a map of solid 20% PI, then using the thresholds to limit it, I limited PI to 0% up to 2000 rpm, and out to 1.0 load. I made a pic of the table, above, and the effective percentages, below.

[Td-d]

Originally Posted by moto-mike

FYI there are limits that we identified a year or two back that prevent precise targeting of the DI/PI mixture. EcuTek has fixed this a good while back but you may not have access to that on open source or other platforms. You'll be limited to about 35-70% range IIRC if that is the case.

35% to 75% I believe, if I'm looking at the right piece of code.

[KoolBRZ]

I tried setting PI to 20%, but it went up over 50%, much less 20%, so I made another table with the cells covered by the threshold zeroed out. Made absolutely no difference. Then I zeroed out the whole table except for the highest rpm row and the highest load row. The PI's still all over the place. Take a look at the datalogs. The only way I was able to shut off the PI completely was to zero out the whole table, and it ran great.
1st datalog with just some of the table zeroed out, http://datazap.me/u/koolbrz/log-1458196461?log=0&data=1
2nd datalog with almost the whole table zeroed out, http://datazap.me/u/koolbrz/log-1458...0&data=1-12-13
and pics of both tables.