Cam timings and AFR shortly after start-up - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

tomm.brz · 03-12-2018, 10:52 AM

Hi guys,
in my ecutek tune I noticed that after starting up the engine (when cold start just make it for longer but also warmish start is doing it)
fuel system ststus =1 lasts only few seconds, then goes to closed loop and AFR and cam timings go to values in this log:

https://datazap.me/u/tommbrz/definit...=6-14-28-30-31

AFR Target and Actual goes to 15.10 and Cam intake and exhaust to 2 / -4
After 2 minutes goes finally to open loop idle with correct AFR as tables dictate, 14.7 and cam timings both to 0
Then after all is warmed up goes back to the correct closed loop mode and everything is as expected

Why do I get afr of 15.10 when the car is super cold when actually should be made richer by the maf offset? also dont understand the 2/-4 cam timings

Thanks

steve99 · 03-12-2018, 11:19 AM

02 sensors don't read reliably till they get up to operating temperature and they actually have a heater to assist warmup.

Have a look at the "fuel quantity Total" parameter at the start fuel quantity is 17 and the AFR is 15, yet later on the Fuel quantity is 12 and afr is 14.5. yes the rpm has come down say 10% but the fuel quantity has reduced by around 30% yet AFR is richer. the whole time the fuel quantitly is getting less yet afr is getting richer. Seems to suggest the 02 sensor isn't reading correctly at the start probably not up to temp yet.

no idea why the target afr would be 15, but it starts to ramp down , have to ask Subaru/Toyota engineers, thiers lots of offsets and compensations applied at idle and at cold start. likely lots of stuff no one has bothered to reverse engineer the logic or find the control tables

gather this was cold startup

the cams are not active at idle, the small movements of 2 or 4 degrees are fairly insignificant and probably just within the sensor/actuator tolerances . or the ecu is calibrating/checking don't really know.

tomm.brz · 03-12-2018, 11:29 AM

Ok for the afr, makes me more comfortable
the cam settings if I put stock tune, they are fixed at 0 the whole time
The cam timings maps are nothing extraordinary, they are just copypasted from stage2 uel ots rom

tomm.brz · 03-12-2018, 11:48 AM

Nope, just triee again a stock tune, its doing the same both afr and cam

thanks Steve

03-12-2018, 10:52 AM	#1
tomm.brz Senior Member Join Date: Jan 2017 Drives: brz 2017 hksv2 Location: italy Posts: 2,280 Thanks: 515 Thanked 1,121 Times in 811 Posts Mentioned: 70 Post(s) Tagged: 0 Thread(s)	Cam timings and AFR shortly after start-up Hi guys, in my ecutek tune I noticed that after starting up the engine (when cold start just make it for longer but also warmish start is doing it) fuel system ststus =1 lasts only few seconds, then goes to closed loop and AFR and cam timings go to values in this log: https://datazap.me/u/tommbrz/definit...=6-14-28-30-31 AFR Target and Actual goes to 15.10 and Cam intake and exhaust to 2 / -4 After 2 minutes goes finally to open loop idle with correct AFR as tables dictate, 14.7 and cam timings both to 0 Then after all is warmed up goes back to the correct closed loop mode and everything is as expected Why do I get afr of 15.10 when the car is super cold when actually should be made richer by the maf offset? also dont understand the 2/-4 cam timings Thanks

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03-12-2018, 11:19 AM	#2
steve99 Banned Join Date: Dec 2013 Drives: FT86 Location: Australia Posts: 7,996 Thanks: 1,035 Thanked 4,994 Times in 2,984 Posts Mentioned: 598 Post(s) Tagged: 2 Thread(s)	02 sensors don't read reliably till they get up to operating temperature and they actually have a heater to assist warmup. Have a look at the "fuel quantity Total" parameter at the start fuel quantity is 17 and the AFR is 15, yet later on the Fuel quantity is 12 and afr is 14.5. yes the rpm has come down say 10% but the fuel quantity has reduced by around 30% yet AFR is richer. the whole time the fuel quantitly is getting less yet afr is getting richer. Seems to suggest the 02 sensor isn't reading correctly at the start probably not up to temp yet. no idea why the target afr would be 15, but it starts to ramp down , have to ask Subaru/Toyota engineers, thiers lots of offsets and compensations applied at idle and at cold start. likely lots of stuff no one has bothered to reverse engineer the logic or find the control tables gather this was cold startup the cams are not active at idle, the small movements of 2 or 4 degrees are fairly insignificant and probably just within the sensor/actuator tolerances . or the ecu is calibrating/checking don't really know.

03-12-2018, 11:29 AM	#3
tomm.brz Senior Member Join Date: Jan 2017 Drives: brz 2017 hksv2 Location: italy Posts: 2,280 Thanks: 515 Thanked 1,121 Times in 811 Posts Mentioned: 70 Post(s) Tagged: 0 Thread(s)	Ok for the afr, makes me more comfortable the cam settings if I put stock tune, they are fixed at 0 the whole time The cam timings maps are nothing extraordinary, they are just copypasted from stage2 uel ots rom

03-12-2018, 11:48 AM	#4
tomm.brz Senior Member Join Date: Jan 2017 Drives: brz 2017 hksv2 Location: italy Posts: 2,280 Thanks: 515 Thanked 1,121 Times in 811 Posts Mentioned: 70 Post(s) Tagged: 0 Thread(s)	Nope, just triee again a stock tune, its doing the same both afr and cam thanks Steve

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