Help with Ecoboost logs – knock & AFR values
06-20-2014, 03:20 PM
#1
Senior Member
Thread Starter
Help with Ecoboost logs – knock & AFR values
Looking for some assistance understanding my log data and how to interpret the knock sensor values. These log snapshots are from a 3rd gear pull using SCT LiveLink.
BOOST:
First, here is the boost and RPM plot. Boost highlighted in bold orange line. Pretty straightforward, boost spikes at 16psi (y-axis) with full-spool about 3.5s into the log (x-axis). Nothing much out of the ordinary here, runs out of breath up.
AFR:
Here’s where it gets a little odd. Same boost curve on top of graph and AFR (14.7:1) in the bold purple line. What’s weird is after full spool the AFR is looking good at 12.5. Nice and safe but lean enough to produce power. Then however, at the 8.5s mark (red vertical line), suddenly there’s a bunch of fuel added, and the result at 9s the AFR goes rich to 11 then continues to pig rich to 10:1. So why did the PCM throw a bunch of fuel at the 8.5s mark?
TIMING:
Similar to the above, timing starts to ramp at spool, and at the same 8.5s mark (when fuel was added) the timing takes a slight jump to advance, then progressively continues on a slow & steady advance through redline (yes this is a weak tune).
KNOCK:
So it all comes down to knock sensor values. The PID I’m pulling is “knock sensor retard” measured in degrees.
My understanding of the knock sensor data is any positive value is an indication of detonation (the higher the positive value the worse the knock). So the same logic must be true for negative values. In the graph above, the knock sensor starts reading more and more negative up to the 8.5s mark where it’s at -2.5. Is this some threshold where the PCM tries to push for more power by adding more fuel and (slight) increase in timing? What’s interesting is that after the 8.5s mark, the knock sensor start leaning back towards 0 after the bump in fuel/timing.
So is this how the knock sensor works in this application?
Also, is there any way to measure injector duty cycle or injector pulse width? I can’t seem to find this anywhere in the available PIDs, just fuel pump and pressure related measurements.
BOOST:
First, here is the boost and RPM plot. Boost highlighted in bold orange line. Pretty straightforward, boost spikes at 16psi (y-axis) with full-spool about 3.5s into the log (x-axis). Nothing much out of the ordinary here, runs out of breath up.
AFR:
Here’s where it gets a little odd. Same boost curve on top of graph and AFR (14.7:1) in the bold purple line. What’s weird is after full spool the AFR is looking good at 12.5. Nice and safe but lean enough to produce power. Then however, at the 8.5s mark (red vertical line), suddenly there’s a bunch of fuel added, and the result at 9s the AFR goes rich to 11 then continues to pig rich to 10:1. So why did the PCM throw a bunch of fuel at the 8.5s mark?
TIMING:
Similar to the above, timing starts to ramp at spool, and at the same 8.5s mark (when fuel was added) the timing takes a slight jump to advance, then progressively continues on a slow & steady advance through redline (yes this is a weak tune).
KNOCK:
So it all comes down to knock sensor values. The PID I’m pulling is “knock sensor retard” measured in degrees.
My understanding of the knock sensor data is any positive value is an indication of detonation (the higher the positive value the worse the knock). So the same logic must be true for negative values. In the graph above, the knock sensor starts reading more and more negative up to the 8.5s mark where it’s at -2.5. Is this some threshold where the PCM tries to push for more power by adding more fuel and (slight) increase in timing? What’s interesting is that after the 8.5s mark, the knock sensor start leaning back towards 0 after the bump in fuel/timing.
So is this how the knock sensor works in this application?
Also, is there any way to measure injector duty cycle or injector pulse width? I can’t seem to find this anywhere in the available PIDs, just fuel pump and pressure related measurements.
06-20-2014, 11:32 PM
#3
F150 Forum
send me your log to erick@leadingedgetuning.com and I will be glad to take a look at it for you...I do it for forum members all the time to give them feedback...
06-21-2014, 08:40 AM
#4
Senior Member
Thread Starter
This is the stock PCM program. Probably not worth sending for any further analysis, I was just curious how the knock sensor worked with the negative values. But I definitely appreciate the offer and will surely take you up on it in the future!
Am I correct in the understanding that negative values from the knock sensor will instruct the PCM to push for more power? I'm only used to environments where knock is either present or not, and positive knock will pull timing only. But negative knock calling for more power is new to me.
Am I correct in the understanding that negative values from the knock sensor will instruct the PCM to push for more power? I'm only used to environments where knock is either present or not, and positive knock will pull timing only. But negative knock calling for more power is new to me.
06-21-2014, 09:06 AM
#5
F150 Forum
This is the stock PCM program. Probably not worth sending for any further analysis, I was just curious how the knock sensor worked with the negative values. But I definitely appreciate the offer and will surely take you up on it in the future!
Am I correct in the understanding that negative values from the knock sensor will instruct the PCM to push for more power? I'm only used to environments where knock is either present or not, and positive knock will pull timing only. But negative knock calling for more power is new to me.
Am I correct in the understanding that negative values from the knock sensor will instruct the PCM to push for more power? I'm only used to environments where knock is either present or not, and positive knock will pull timing only. But negative knock calling for more power is new to me.
