Fuel Injector Duty over 100% ?

thomasj · 03-15-2006, 01:29 PM

I wasn't hitting peak boost using a Cobb AP Stage 2 map (I was hitting about 15.0) so I shortened the length of my wastegate actuator by one full turn. I'm peaking at nearly at 15.7 now and have seen 15.8 once on a cooler night. I'm in Florida so we're not blessed with the best combustion-happy weather.

With that said, I figured I'd do logging with ECU Explorer to see how things were holding up.

Fuel Injector #1's duty cycle hit over 100% on several occasions. I'm not sure why that is. See this link for my data log. It's from a 5 mph to 131 mph run. I pretty much redlined 1st through 4th gear to demonstrate full load on the car so I could pinpoint potential issues.

Can somebody review this spreadsheet and offer insight? I didn't see any negative knock correction while in boost so I'm happy with that. However, if someone sees ANY other issues or can advise on the FI duty, let me know.

It only contains about 30 seconds worth of data so it's not that painful to look through. I put together some charts together in the spreadsheet too for giggles.

http://thomasj.org/subie/2006-03-14-ecu-logging.xls

Thanks in advance.

Tom

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rjrutzky · 03-15-2006, 01:52 PM

Stage 2 on stock injectors = 100% duty. Simple as that.

thomasj · 03-15-2006, 03:34 PM

Thanks for the fast response. I was thinking about shortening the wastegate actuator arm another 1/2 - 1 turn in hopes of hitting 16 psi regularly. Based on the numbers in this spreadsheet do you have any idea of how much more boost I could safely run before a) running too lean and/or b) putting too much pre-load on the wastegate?

I'm at about 11.25:1 AFR right now on full throttle.

rjrutzky · 03-15-2006, 04:02 PM

Quote:

Originally Posted by thomasj

Thanks for the fast response. I was thinking about shortening the wastegate actuator arm another 1/2 - 1 turn in hopes of hitting 16 psi regularly. Based on the numbers in this spreadsheet do you have any idea of how much more boost I could safely run before a) running too lean and/or b) putting too much pre-load on the wastegate?

I'm at about 11.25:1 AFR right now on full throttle.

Is that a wideband reading? You are already too lean IMO. I would turn the boost down instead of up. 11.5 afr and 30 deg timing at redline in 4th is scary to me unless your running 100+ octane.

thomasj · 03-15-2006, 04:31 PM

Thank you for the fast response and the tips.

It's a narrow band sensor (Air Fuel Sensor #1 according to the ECU) that's already in the car. With that said, hopefully, the reading is slightly inaccurate in my favor. That's just wishful thinking, though.

Also, I was running roughly 94 - 94.5 octane gas at the time of this test. Maybe I should try again with just 93 to see if it richens at all.

Do you have any tips in getting closer to target boost without running the HWG map or further preloading the wastegate actuator? Thanks again.

TravisSTi · 03-15-2006, 04:31 PM

There are a few things you can do to lower the Injector duty. Lower your boost in that range, get larger injectors, or a water injection system.

boundy3 · 03-15-2006, 06:19 PM

11.25 is the lowest the stock AF sensor will read.

I too have seen over 100% IDC and I'm only stage 1.

I remembering reading a while back about others also seeing greater than 100% IDC and there being talk about how IDC is calculated and is not completely accurate (obviously since were seeing over 100%).

The only real way to see if your not getting enough fuel is to do some logs with a wideband.

Did you do any logs before you turned the wastegate, and were you seeing the same IDC%'s?

good luck, and I wouldn't worry about it too much.

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03-15-2006, 01:29 PM	#1
thomasj Scooby Newbie Member#: 103890 Join Date: Dec 2005 Vehicle: 2005 WRX Silver	Fuel Injector Duty over 100% ? I wasn't hitting peak boost using a Cobb AP Stage 2 map (I was hitting about 15.0) so I shortened the length of my wastegate actuator by one full turn. I'm peaking at nearly at 15.7 now and have seen 15.8 once on a cooler night. I'm in Florida so we're not blessed with the best combustion-happy weather. With that said, I figured I'd do logging with ECU Explorer to see how things were holding up. Fuel Injector #1's duty cycle hit over 100% on several occasions. I'm not sure why that is. See this link for my data log. It's from a 5 mph to 131 mph run. I pretty much redlined 1st through 4th gear to demonstrate full load on the car so I could pinpoint potential issues. Can somebody review this spreadsheet and offer insight? I didn't see any negative knock correction while in boost so I'm happy with that. However, if someone sees ANY other issues or can advise on the FI duty, let me know. It only contains about 30 seconds worth of data so it's not that painful to look through. I put together some charts together in the spreadsheet too for giggles. http://thomasj.org/subie/2006-03-14-ecu-logging.xls Thanks in advance. Tom * Registered users of the site do not see these ads.

03-15-2006, 01:52 PM	#2
rjrutzky Scooby Specialist Member#: 30367 Join Date: Nov 2002 Chapter/Region: South East Location: nashville, tn Vehicle: 2005 Legacy GT NASA SE PTB Champ	Stage 2 on stock injectors = 100% duty. Simple as that.

03-15-2006, 03:34 PM	#3
thomasj Scooby Newbie Member#: 103890 Join Date: Dec 2005 Vehicle: 2005 WRX Silver	Thanks for the fast response. I was thinking about shortening the wastegate actuator arm another 1/2 - 1 turn in hopes of hitting 16 psi regularly. Based on the numbers in this spreadsheet do you have any idea of how much more boost I could safely run before a) running too lean and/or b) putting too much pre-load on the wastegate? I'm at about 11.25:1 AFR right now on full throttle.

03-15-2006, 04:31 PM	#5
thomasj Scooby Newbie Member#: 103890 Join Date: Dec 2005 Vehicle: 2005 WRX Silver	Thank you for the fast response and the tips. It's a narrow band sensor (Air Fuel Sensor #1 according to the ECU) that's already in the car. With that said, hopefully, the reading is slightly inaccurate in my favor. That's just wishful thinking, though. Also, I was running roughly 94 - 94.5 octane gas at the time of this test. Maybe I should try again with just 93 to see if it richens at all. Do you have any tips in getting closer to target boost without running the HWG map or further preloading the wastegate actuator? Thanks again.

03-15-2006, 04:31 PM	#6
TravisSTi Scooby Newbie Member#: 51243 Join Date: Dec 2003 Chapter/Region: MAIC Location: NOVA Vehicle: 2004 Subaru WRX STi WRB - GTX30r	There are a few things you can do to lower the Injector duty. Lower your boost in that range, get larger injectors, or a water injection system.

03-15-2006, 06:19 PM	#7
boundy3 Scooby Specialist Member#: 54598 Join Date: Feb 2004 Chapter/Region: South East Location: Orlando Vehicle: 2004 WRX Sedan WR Blue Pearl #68 STX	11.25 is the lowest the stock AF sensor will read. I too have seen over 100% IDC and I'm only stage 1. I remembering reading a while back about others also seeing greater than 100% IDC and there being talk about how IDC is calculated and is not completely accurate (obviously since were seeing over 100%). The only real way to see if your not getting enough fuel is to do some logs with a wideband. Did you do any logs before you turned the wastegate, and were you seeing the same IDC%'s? good luck, and I wouldn't worry about it too much.