Expected injector duty cycle for ~250RWHP

[armstrom]

I've been digging through some of the posted data logs but can't find something comparable to my setup with all the logged parameters I need. My car is stock except for a Harrop SC and Gruppe-S UEL header/overpipe.

I haven't had the car on a dyno yet but I expect it should be in the neighborhood of 240-250 RWHP based on comparable cars. Port injector duty cycle is maxing out around 38% with direct injectors running at ~5.4ms. My AFRs are ~12.1 : 1 under boost (max of 9psi at redline).

Here's a datalog for reference.
http://www.datazap.me/u/armstrom/wot...-6-18-19-30-36

Is my amount of fuel reasonable? I don't want to spend lots of time and money searching for a mechanical problem that just doesn't exist.
-Matt

[steve99]

Great info here
http://www.ft86club.com/forums/showp...2&postcount=17

From @moto-mike
"I have grown to LOVE the split DI/PI system on this car. It is more work--yes, but in practice it works incredibly well. Out of all the things we can tweak on this car to make power, the DI/PI ratios and timings are the least touched. The engineers knew what they were doing here, and any tuner who actually spent time trying out the different variations empirically, will be using something very similar to OEM.

The reality here is that DI works BEST by injecting in a very narrow window, just as @arghx7 outlined. Too early and you're blowing out the exhaust, too late and you're still injecting when the combustion event goes off. Another factor is that you don't want to inject too far away from the spark, that's why it isn't just 370 across the board.

We've seen some tuners swear by DI only, and others use 50/50 split or even full on PI in really high HP applications. I don't think either one is a good solution.

Think of it this way: DI fuel delivery will always be the optimal method, UNTIL you make the mixture too unstable or wash the cylinders. Wash is unlikely, but once you approach 7ms injection times (250+whp with e85) you begin to lose some of that benefit. The mixture becomes less stable. Between about 300whp you cross over the threshold where 35% PI has no negative effect. 20% PI on OEM tunes? We have found absolutely no repeatable HP gains, as in 0, like none-what-so-ever. Despite changes in timing, leaner or richer, more or less aggressive cam timing, or different injection timings...I think one car actually made 1hp over 20% PI mix...which is within the margin of error between runs.

So in reality, there's just no reason to overstress the DI system with long IPWs. Take advantage of the dual injection, max out the DI to about 6 ms (this way in sub freezing temperatures you have headroom) and then run port at no more than 80% duty cycle, or about 15ms.

Also, as a comparison the DI equipped FA20 in the 15 WRX...we can't run half the timing on those! DI only we hit the knock threshold at a much lower HP using DI only. Can't explain it and it's still a very new system, but it made me wish for the BRZ setup having tuned it. "

[Kodename47]

Originally Posted by armstrom

I've been digging through some of the posted data logs but can't find something comparable to my setup with all the logged parameters I need. My car is stock except for a Harrop SC and Gruppe-S UEL header/overpipe.

I haven't had the car on a dyno yet but I expect it should be in the neighborhood of 240-250 RWHP based on comparable cars. Port injector duty cycle is maxing out around 38% with direct injectors running at ~5.4ms. My AFRs are ~12.1 : 1 under boost (max of 9psi at redline).

Here's a datalog for reference.
http://www.datazap.me/u/armstrom/wot...-6-18-19-30-36

Is my amount of fuel reasonable? I don't want to spend lots of time and money searching for a mechanical problem that just doesn't exist.
-Matt

What issue do you think you have?

[armstrom]

Originally Posted by Kodename47

What issue do you think you have?

I don't think I have any issue. My tuner is telling me that something is wrong since it shouldn't need that much fuel to keep the AFRs down but I don't think the amount of fuel is too much. That's why I posted though, trying to find corroboration from the community at large. I'm perfectly happy to accept my car has a problem, but I have no idea where to start looking for one based on the info I've seen.
-Matt

Sent from my XT1650 using Tapatalk

[Kodename47]

Originally Posted by armstrom

I don't think I have any issue. My tuner is telling me that something is wrong since it shouldn't need that much fuel to keep the AFRs down but I don't think the amount of fuel is too much. That's why I posted though, trying to find corroboration from the community at large. I'm perfectly happy to accept my car has a problem, but I have no idea where to start looking for one based on the info I've seen.
-Matt

I've just looked at a log for a similar setup, everything appears about right.

[BRZoomTX]

Your wide open throttle portion looks great, however you are definitely having a fueling error somewhere. Your short term trims are near maxing out with how much fuel its pulling shortly before your WOT pull. Reference my screenshot below.

Your trims on a "finished" tune would be expected to be around 10%, 15% at worst. Anything higher than that indicates a calibration error somewhere in the tune, or a mechanical issue. Since WOT looks so good I'd lean towards a tune calibration issue. You're hitting lamda targets, but the ECU is taking away ~25% fuel to hit those targets. If you had a mechanical issue, your car probably wouldn't be running as good in WOT. You're still within adjustable levels for the ECU (it can correct up to around ~30%), but this high is definitely not good.

Take a longer log of you just cruising around and review that data. That will give you more insight in to what is happening. Your tuner is correct, there is a fueling issue, you were just initially looking at the wrong data.

[armstrom]

Originally Posted by BRZoomTX

Your wide open throttle portion looks great, however you are definitely having a fueling error somewhere. Your short term trims are near maxing out with how much fuel its pulling shortly before your WOT pull. Reference my screenshot below.

Your trims on a "finished" tune would be expected to be around 10%, 15% at worst. Anything higher than that indicates a calibration error somewhere in the tune, or a mechanical issue. Since WOT looks so good I'd lean towards a tune calibration issue. You're hitting lamda targets, but the ECU is taking away ~25% fuel to hit those targets. If you had a mechanical issue, your car probably wouldn't be running as good in WOT. You're still within adjustable levels for the ECU (it can correct up to around ~30%), but this high is definitely not good.

Take a longer log of you just cruising around and review that data. That will give you more insight in to what is happening. Your tuner is correct, there is a fueling issue, you were just initially looking at the wrong data.

Yeah. My tune actually has closed loop fueling under WOT and uses speed density above 2k. The concern is that the closed loop fuel is what is keeping my afr in check. But it is supposedly maxing out its ability to add fuel. The tuner is confident in the VE map he uses but I'm really starting to think the base fuel map is just not right. He wants me to look for exhaust leaks and vacuum /boost leaks but I'm not seeing any evidence of either.
-Matt

Sent from my XT1650 using Tapatalk

[BRZoomTX]

Originally Posted by armstrom

My tune actually has closed loop fueling under WOT and uses speed density above 2k.

SD above 2k? So he is using MAF for everything under that, and the fueling error is on your MAF based closed loop operation outside WOT. I'm willing to bet all of your low load closed loop operation has similar fuel trims.

Intentionally breaking closed / open loop operation to "force fueling maps" is not a substitute for a proper tune. This is why he did it, and its also why he is seeing fueling issues. He is forcing closed loop to make setting up speed density easier. You should not need a speed density setup at your power level. Instead, he should focus his efforts on properly scaling MAF / injectors and making sure everything is running properly before moving on to VE tuning. In fact, it seems like he switched to VE based tuning to "bypass" issues in the tune, maybe because he couldn't figure out the base MAF based fueling good enough, which your log clearly indicates imo.

Additionally, your car will run much better and be much more responsive on a MAF based setup. That doesn't mean you can't get SD working great, but most EcuTek tuners use a hybrid MAF / SD mix for superior daily driveability just because MAF based fueling is much more smooth for transitional areas. You really don't need SD in your situation, even "only over 2k". You won't benefit from a SD setup much until you're maxing out your MAF, which doesn't happen until north of 400hp depending on MAF housing size.

Read through the EcuTek documentation. Even if you aren't familiar with tuning in general, the docs will clarify a lot of this for you and connect a lot of dots.