Partial Throttle Issue - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

sw20kosh · 07-17-2014, 10:43 PM

Just wondering if anyone else has an idea of what is going on here:

Setup:
ptuning turbo kit
stock injectors
ptuning specific MAF scaling
ECUTEK tune

Everything runs great. Car makes good power 280 on 91 octane. Maintains great WOT AFR 11.8 ish.

Until you do partial throttle at the 4k rpm zone. If you hold a constant 30% throttle position starting at 3500 rpms, it feels like the engine loses some 'umph' (dead zone) as you climb the rpm range and then all of a sudden, somewhere north of 4k rpm the power will come back and you surge forward.

In the logs, this is the only thing that correlates (MAF voltage is nice and smooth):

This is a plot of Wideband AFR.

Thanks for any input.

Kodename47 · 07-18-2014, 03:22 AM

Well that looks like it's going lean. The power returns as the AFR returns to a decent level. Any chance you have the corresponding view for fuel system status? If it's already in open loop then you will need to sort out the MAF to bring the AFRs down in that region, or just make the AFRs richer in the fuel table for the RPM/Load region.

sw20kosh · 07-18-2014, 12:16 PM

Quote:

Originally Posted by Kodename47

Well that looks like it's going lean. The power returns as the AFR returns to a decent level. Any chance you have the corresponding view for fuel system status? If it's already in open loop then you will need to sort out the MAF to bring the AFRs down in that region, or just make the AFRs richer in the fuel table for the RPM/Load region.

Here are two new logs. Purple is AFR. Blue is Fuel Sys Status.

Kodename47 · 07-18-2014, 01:32 PM

Well it looks fine as soon as it goes into OL. It looks like the CL needs to richen off slightly (if that's possible, I haven't really played with CL fueling) or maybe try getting it to transition into OL a little sooner.

The dead spot is definitely because it's getting leaner and then when the fueling reaches a good ratio again, that is where you feel the lurching forward.

sw20kosh · 07-18-2014, 03:33 PM

Quote:

Originally Posted by Kodename47

Well it looks fine as soon as it goes into OL. It looks like the CL needs to richen off slightly (if that's possible, I haven't really played with CL fueling) or maybe try getting it to transition into OL a little sooner.

The dead spot is definitely because it's getting leaner and then when the fueling reaches a good ratio again, that is where you feel the lurching forward.

Yep tuner is looking into the CL issue. Hopefully it is figured out! Thanks for your analysis! I really appreciate it.

07-17-2014, 10:43 PM	#1
sw20kosh Senior Member Join Date: Jul 2012 Drives: 2013 Black FR-S Location: SF Posts: 3,030 Thanks: 881 Thanked 2,014 Times in 990 Posts Mentioned: 153 Post(s) Tagged: 1 Thread(s)	Partial Throttle Issue Just wondering if anyone else has an idea of what is going on here: Setup: ptuning turbo kit stock injectors ptuning specific MAF scaling ECUTEK tune Everything runs great. Car makes good power 280 on 91 octane. Maintains great WOT AFR 11.8 ish. Until you do partial throttle at the 4k rpm zone. If you hold a constant 30% throttle position starting at 3500 rpms, it feels like the engine loses some 'umph' (dead zone) as you climb the rpm range and then all of a sudden, somewhere north of 4k rpm the power will come back and you surge forward. In the logs, this is the only thing that correlates (MAF voltage is nice and smooth): This is a plot of Wideband AFR. Thanks for any input. Last edited by sw20kosh; 07-18-2014 at 12:11 AM.

07-18-2014, 03:22 AM	#2
Kodename47 Senior Member Join Date: Oct 2012 Drives: UK GT86 Location: UK Posts: 3,040 Thanks: 185 Thanked 1,629 Times in 1,112 Posts Mentioned: 155 Post(s) Tagged: 1 Thread(s)	Well that looks like it's going lean. The power returns as the AFR returns to a decent level. Any chance you have the corresponding view for fuel system status? If it's already in open loop then you will need to sort out the MAF to bring the AFRs down in that region, or just make the AFRs richer in the fuel table for the RPM/Load region. __________________ .: Stealth 86 :. Abbey Motorsport/K47 Tuned Sprintex 210 Supercharger Kodename 47 DJ: Soundcloud / Instagram / Facebook

07-18-2014, 01:32 PM	#4
Kodename47 Senior Member Join Date: Oct 2012 Drives: UK GT86 Location: UK Posts: 3,040 Thanks: 185 Thanked 1,629 Times in 1,112 Posts Mentioned: 155 Post(s) Tagged: 1 Thread(s)	Well it looks fine as soon as it goes into OL. It looks like the CL needs to richen off slightly (if that's possible, I haven't really played with CL fueling) or maybe try getting it to transition into OL a little sooner. The dead spot is definitely because it's getting leaner and then when the fueling reaches a good ratio again, that is where you feel the lurching forward. __________________ .: Stealth 86 :. Abbey Motorsport/K47 Tuned Sprintex 210 Supercharger Kodename 47 DJ: Soundcloud / Instagram / Facebook

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