I decided to throw together a little calculation tool for DI angles etc. Let me know what you guys think, it's obviously based on assumptions of the exhaust cam angle and DI SOI so I can't guarantee it's accuracy.

Download Link - Kodename47's Direct Injection Calculator

Have you guys tried going 100% DI at the lower speeds? It looks like Toyota went 100% DI at the peak scavenging areas closer to 2K rpm to avoid fuel short circuiting during scavenging (HC emissions) caused by PI but in the speeds before that it should be possible to go 100% DI as well and take advantage of the knock relief. I am not sure why they did not do it unless they thought the fuel mixing with 100% DI would be poor causing Soot.

I'm sure you could go 100% DI earlier and I'm certain some tuners do. However I would put money that at lower loads there might be some benefits to PI as well as the cleaning properties. However it could be beneficial to start using DI earlier in mid to high load over 2k.

Hi guys,

I just got my FRS and a ECUTEK tuner but I have been tuning engines for years, started with holley carbs...

I think that it's more about drive ability...
I'm going to run both at all times to eliminate the transition point from DI to both...

Turing PI on and off and on again makes no sense to me. either on or off or a mix..

I have to do some tweaking, I filled in some gaps with 10% PI and it seams too low but it still runs better, so I'll go to a min of 20% PI at all times....

The 35% - 20% PI part of the map run better to me than either 0 or 10%...

Keep us posted with more information and progress. Any data is greatly appreciated.

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Running too low PI could lead to running at regions lower than the Min Pulsewidth. Every injector has a minimum pulsewidth which is usually 1ms for the type of injectors used in the FRS. I would advise using completely no PFI or partial (like 30-40% PFI) but never too low. As we go towards higher speeds and loads this is no longer a problem since a low 10% still results in a decent pulsewidth at peak power etc

Great thread!
Usually the SOI is about 40deg after TDC during the Intake stroke to avoid piston wetting. Normally the injection should end atleast 60deg before TDC firing for good mixture preparation (thumb rule). Essentially we have about 360-40-60 = 260deg. At peak engine speed of 7500rpm we have 8ms per 360deg. This reduces to 5.77ms for 260deg. So the number @Kodename47 is referring to is the absolute max PW that should be used before running into issues. At this time it is beneficial to start relying on some PFI for better mixture preparation (improves flame speed) instead of relying heavily on DI for knock relief. Saying this because at those high speeds we have seen combustion only a few degrees away from MBT considering this was calibrated on premium fuel.

From what I can see there will be more benefit from reducing enrichment for thermal protection than anything else. This is exactly what @shiv@vishnu has done. OEMS go crazy on thermal protection and sometimes run ridiculously high FAR (closer to 0.10) From my experience a FAR of 0.088 to 0.09 is enough to protect CAT and Exhaust at peak power. I think the OFT tune puts the engine just there.

For those running CATless headers they probably can push the AFR even a touch leaner. For those with OEM header I would not recommend any leaner than 0.085 at peak power.

There are certain engine speeds where engine is more knock limited than others. You can see this by looking at the stock spark timing. If at certain engine speed the spark advance is less than the adjacent speeds it indicates that this speed is more knock limited in normal setting. At these speeds you need a tad more enrichment since the spark is more retarded. In general the more spark you add the less enrichment you need.

@thambu19 did you look at my DI calculator I posted earlier? The DI injection timing is in the Romraider definitions.

I saw your linearization curve of pulsewidth to injector mass. For engines running constant rail pressure that goes out of the equation. From your analysis I think this engine has varying rail pressure.

This table is what gets used when engine is running open loop fuelling combined with airflow estimation. Usually this table is not messed with unless for E85 conversion. One easy way to make an engine accept E85 without messing with MAF scaling is to adjust this pulsewidth to mass curve and move it up by roughly 40% so the engine commands larger pulsewidth for the same requested fuel mass which is indeed calculated from airflow prediction/measurement.

Adjusting the MAF scaling isnt really the appropriate way to adjust for E85. If you think about it the airflow doesnt really change just because we are running E85 and as a matter of fact it actually drops due to the higher Fuel to Air ratio

Thanks for the info...
I'm going to raise up PI in those areas to smooth out the power curve some more...

I meant this:
DI Calculator

I'm very much aware that the ratio/injection timing is only part of the picture as the IPW changes, I log both volume and PW for both PI and DI all the time ;)

Nice sheet. Are you planning to use this to calculate the time available for injection and hence max PW?

Pretty much why I did it. Have a look and play, you can copy your own tables into it.

Very excited to get home and look at this. I swear I've seen low 6ms DI PW on my logs, but I think they were somewhere in the low 6k RPM range. 7psi E85 fully stock fueling. I'd wager somewhere around 260 g/s MAF. Wonder how much fueling headroom I have if I tweak the PI/DI ratios.

6ms at 6K rpm wont be a problem but 6ms at 7.5K might be at the edge.

Are you sure about 260g/s?

I expect them to be in the 150-170 g/s range

With 220g/s air one could make close to 300hp

So I ran a few changes today and seams like ( seat of the pants) the sweet spot is 20% to 25 % PI for best drive ability and acceleration..
It will still pull good at 35% but seams to lag then pull...
DI seams to respond quicker more instant but pulls harder with some PI mixed in...
And the sweet spot seams to be 20% to 25 %, Toyota may have been right on that one.

I'm currently at 35% below 2000 rpm and either 20% or 25% above 2000 rpm in all cells but .100 column...
So I'm running 35% to 20% PI at all times and it's running great...

I will probably go to 20% above 2000...
I have to get out and do some more runs and data log...

I am surprised that this is making a difference in drive feel. Usually it is just down to the emissions and fuel economy. In theory PFI should give better and more consistent mixing compared to DI and hence has faster 0-10% burn at low speeds and loads.

I'm not 100% sure on the MAF. Came home to a broken A/C last night so didn't get a chance to look at the logs. Totally reasonable that it was 160g/s instead of 260g/s.

I went back to 20% Toyota had it right...
The more PI you add it feels richer but I don't think it is, it just just feels rich..
But too little feels lean... I'm sure if you readjust the fuel maps it will make the same HP... But for drive ability 20% seams to be the sweet spot......

I went to 35% below 2000 rpm and 20.3 above in all cells...
Turing the PI on and off and on was making the torque dip worse and too much PI made the dip worse... I have a slight 500 rpm dip, in 1st gear I can't feel any dip...

Computers have made tuning too detailed... If you are going to run PI you will have the best transition to run them all the time.. unless there is a good reason to turn them off why would you... and not in the middle of the torque dip... Both PI and DI have advantages and disadvantages and it seams a mix is best...

Interesting.

I was about to try this on my car, as I was wondering if going from 0 to 20 or 50% PI and back across load/rpm cells was making some fueling erratic by putting the PI pulsewidths in the non-linear range like the problem switching PI on and off in low loads at idle.

@shr133 are you dyno testing this?

@Kodename47 That's what I want to know. All of these threads with people changing the PI/DI ratios and AVCS, etc. saying it "feels" a certain way. The butt dyno is not trustworthy people.

1 of my goals was to get rid of the dip and the dip starts when they turn off PI and change the cam timing and a few other things....
I don't know why you would turn PI on, off and on again.... Running both will smooth it out... At mid load I have no dip in acceleration.... I think turning off PI and the exhaust cam timing is for emissions not performance...

This will never be a drag car so I'm tuning for drive ability and passing power... So I am currently running this on my butt dyno for now till I get the maps sorted out... It doesn't take a genius to know if something works or not...

I'm getting to the point I have to dyno it and start doing 0-60s to sort out the small details... But it runs way better than stock at all rpms...

I don't know if running PI all the time will help HP on a dyno but it will make the engine run better and eliminate 2 transitions that help to cause lag and hesitation...

Just flash it and drive for a day if you don't like it just flash back...

I just can't seem to find the three or specific posts, but the switch to DI only on that range was due to some condition that required the DI cooling effect, too hot a combustion event during that range, something like that. Not sure if they were speculating or some data was provided on that subject... if it was emissions related, tactic to prevent the catalytic converters from spontaneously exploding, or preventing engine damage.

Either way, I'm subscribed to topic and will stay attentive towards everybody's feedback.

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I think I'm running my DI's a bit too hard for sure. Going to have to scale down a bit on the DI ratio at the top end.

Let me know what you guys think.

http://datazap.me/u/incognico/2ndgeare85?log=0&data=

Are you logging PI/DI injection volumes or PW at all? The only reason I ask is that I tested something the other day with 25% PI ratio through the whole of the table (SC car so more volume) and the PIs weren't actually used until quite late and mid/late load. I'm guessing down to minimum volume or PW parameters so something else. I've got more testing to do, I'm trialing an easy way to get PI/DI error minimised without having to run fully PI or fully DI.

I agree that there must be benefits to PI with regards to the mixture benefits, but if you're saying that you didn't feel the dip then you'd see that on a dyno. However I know someone who says that they tested various ratios on a dyno and found little to no benefit from changing them. You really need to test not just the different ratios but the extra ignition timing it allows you to put in as a result.

Try using my DI calculator, it will allow you to set a limit to the PW and calculate it accordingly for you. Also allows you to mess with the tables and see the changes ;)

Calibrating engines day in and day out at work (both dyno and vehicle) I can say one thing. It is extremely hard to verify changes accurately on the road unless you have dynamic calibration where you can change on the fly and feel the difference right away.

If it was my car I would not bother so much about DI at loads that are not knock limited. There is not much to get out of DI other than VE improvement and some added spark. I have experimented with injection timing for PFI from 50deg before IVO to 150deg before IVO and found that the earlier I inject the better the 0-10percent burn and HC at the expense of NOX. Which says if I had gone DI my mixture preparation would have been weaker.

At WOT I would go 100% DI. There is no reason not to unless at the highest of speeds where the spark is almost close to MBT (maybe 10deg from MBT in most cases). Here you may want some PI to reduce the PW of DI since the injection time available is pretty short as the speed increases. 5.8ms in our engine. So here we trade some spark advance for better mixture preparation to eek out better burn.

At idle it is always debated. Companies go DI and it can help hot restart. With engines with high effective compression ratio will get into huge Pre Ignition during a hot restart. Going DI it allows companies to run lean mixture in the first few (1-5) cranking cycles to avoid pre-ignition during cranking. This fuel control is not possible with PFI during cranking.

In my opinion once engine is up and running PFI is better for mixture preparation but companies have to do tradeoffs all the time and stick with one method and in the case of FA20 it is DI I believe.

Did the car come with PI during first cal release and then later get changed to DI? Or was it always DI during start and idling?

Interesting. My calibration is A01G. First second of cranking is full PI, then DI gets added, full DI after around 6-8 seconds. Are later calibrations starting up with DI?

As I mentioned it will depend on the dynamic compression ratio of the engine during cranking. Almost all engines with VVT go to their end stop positions when no cam dutycycle is applied. Most have a pin to keep them in place. When the cams are at this position the Dynamic compression they create is important.

Most Intake cams are locked at their most retarded position and most exhaust cams are at their most advanced position. I believe this is the safe position for most OEMs. A compression ratio of 5:1 is safe for a hot restart (the incylinder air temperature gets extremely hot in a minute of not running). When the engine is re-started the throttle cannot keep the load under 0.3g/rev because the manifold is at ambient pressure with the engine not running. This means during the first few revolutions the engine is seeing 100% VE (not really because intake cams close late into intake stroke) causing pre-ignition.

Ways around it is to delay fueling by a couple of cranking rpm so allow the hot air to be passed through the cylinder or going lean on the first few pulses.

This is more important on stop start engines and less of an issue with key start since the start quality is less of an issue with normal key start. I mean people do not care of the rpm flare up during a normal key start but dont want their engine to roar into life on a stop start event.

If toyota uses the option to not fire fuel in the first couple of cranking pulses then PFI would work. It will also work if their ECR is 5 thereabouts.

OEMs with pure DI will go for two injections with the second injection just before ignition. This way they can retard spark and get a CAT light off during cold starts. During hot starts this isnt a problem anymore and no real need for DI in my opinion. The thing is we dont know how many levels of strategies exist in the Toyota code. If they just want one strategy across all operating conditions they would choose one option vs if they had a cold strategy vs a hot strategy option

When engine is cold PFI helps because upon firing cold fuel on a cold port the fuel gets more time to evaporate in a PFI. Normally the injection timing for a super cold start is much earlier than a warm PFI start. This is also applicable for E85 which takes more time to evaporate.

Once engine is up and running they would be switching to DI for late ignition to fire up the CATs. With DI they can create rich spots around the plugs for this condition.

Does anyone know if the ecu uses MAP sensor reading to calculate load at any time? Is is just the MAF or is the MAP used as well or only if the MAF is faulty?

It's MAF based load.

Now this one is interesting...

So I tried having PI active at least partially all of the time except for idle.
The result of my logging PI duty is below - PI not active where I set my PI ratio at 20% or 24%. Before you ask: yes, I did set all 3 PI ratio tables the same.

I've gone and trawled through the disassembly for the PI/DI ratios and come to the following conclusions:

1. PI ratio (Hot) map is not used based on the A01G disassembly. The threshold for switching between (Cold) and (Warm) maps is ECT <55 or ECT >60 (5 degree hysteresis).

2. If the RPM is over 5000RPM or Load over 1.5 g/rev, the following two thresholds are not applied:

a. If calculated PI_Ratio is over 0.75 and the RPM/Load thresholds are not exceeded, the PI_Ratio is set to 1.00.

b. If the calculated PI_Ratio is under 0.35 and the RPM/Load thresholds are not exceeded, the PI_Ratio is set to 0.00.

ROM addresses for the thresholds in A01G ROM:

Def for above A01G:

@ztan this is strange.. I have the warm to hot ECT thresholds in my definitions (80/75), are you suggesting they aren't used? I guess an obvious test would be to set the 3 tables with flat values and see what happens.

So to sum up, at RPM less than 5k and load under 1.5 then if the ratio is 75% PI it will output 100% PI. This is almost never the case, I doubt anyone sets the PI as high as 75% as you'd simply be under using the DIs.

Anything under 5k RPM and 1.5 load will be 100% DI if the PI Ratio is below 35%. That would certainly explain some behaviour I've noticed before.

I wonder if ECUtek custom maps get around these conditions?

Seems like it does. Just looked over 2 logs from the last few days having set the whole PI Ratio table to 25%. On the standard table I get no PI until over 1.5 load, on the ECUtek custom map I have PI just off idle, where the minimum IPW threshold is met.

Adding and checking these parameter into my A02G definition.

The second ECT threshold (80/75) is defined, but use of that switch in the code is bypassed, at least in A01G stock. Activating that switch requires adjustment of a single float value (at 591AC) in the ROM to greater than 100.0 - Subaru engineers disabled the switch by changing a value in the code rather than re-writing it.

Having said that, I am not sure that there will be any major benefit from having different DI/PI settings at different engine temps.

The subroutine is located at 58F8E if you want to have a go at the disassembly.

HaHa us NA guys dont ever make 1.5 load :-) , but nice to know, maybe they were plannibg a turbo ?

Generally it helps to go PFI when temps are low to avoid wall wetting and wash down and also for better mixture prep. Unless engine is knock limited there is no real need for DI at low loads other than for emissions and to make sure the injectors are not carboned up by those guys who baby their engines. Since they are inside the chamber they have to make sure they are fired more frequently than the PFI injectors.