I could be wrong here, but what the hell. The way I understand the A/F table is that when the values are set to 14.5 the ECU will rely on the O2 sensor to calculate the amount of fuel. When the values are different, the ECU goes to the F tables for the fuel settings. Therefore, changing the values in the A/F table will not cause the ECU to add more fuel. You need to use the Trim table.
Just was Dyno'ed; they say I'm too lean
- Thread starter Willtill
- Start date
Willtill
Nitrous
Hi Harry, I think your right. I've been soliciting advice from the other site as well; and with Dougl's and Brian's input; I feel comfortable in leaving the AF table alone and slightly tweaking the Trims table.
flhtpi
.060 Over
- Joined
- Nov 23, 2009
- Messages
- 200
I agree most A/F ratios are unreliable on dynos. My dyno sheet looks very lean but when we gave it more fuel it lost hp and torque. We then tuned for best hp and torque and didn't worry about the A/F ratio. I'm getting about 29 miles to the gallon, it's not lean!!!
Pig9r
Living Legend
I wouldn't drop them much lower than the surrounding cells.
JRCollings
.040 Over
Ok, so following the conversation so far... What is the point of the A/F table (and the ability to edit it) if the ECU ignores / doesn't use it?
Power-Tripp
Turbocharged
The AF table is not used at wide open throttle - only at steady throttle openings up to about 8% throttle.
It is used to correct idle and cruise with the stock narrow-band Lambda sensor FOR EMISSIONS PURPOSES.
The narrow band sensor, only has a design range of 0.98-1.02 Lambda (14.2786 - 14.8614 AFR). Outside of this range it is not accurate, and the ECU doesn't even use the AF table corrections if cells are set below its range. This is why Wayne MacDonald at TuneBoy recommends setting the cells richer - to keep the ECU from altering the work done when mapping the rest of the tables where the Lambda sensor is normally used.
If you want to enrich the region where you are lean, modify the F tables or Fuel % Trim table at 100% TPS. The graph is only showing 100% TPS, nothing below. It is possible to be lean at 100% TPS, and rich or lean (or a combination) at lower TPS openings. With fuel injection, anything is possible - garbage in, garbage out... and all that. You have to test and tune all loads (TPS and MAP) at all engine speeds for full mapping.
Also, you need to understand that mixture ratios will change slightly when read with a wide-band Lambda sensor on a dyno run. Things like engine, oil, and air temps alter the way fuel is delivered to the cylinder, and how it is burned in the chamber. This alters the residual oxygen in the exhaust gases - which is what the Lambda sensor detects.
When performing a sweep test, the first part of the pull is also affected by the amount of acceleration compensation in the MAP fueling tables (L tables). When you first roll to WOT, the engine demands more fuel for acceleration under load. Getting this correct will help.
Also, be aware that there is a lag time built into the logged mixture ratio, and what is displayed on the dyno graph. The lag is mostly due to the time required for gases to travel from the chamber, to the end of the exhaust, then be pulled into the meter for testing. The faster the bike accelerates, the further the displayed ratio will lag behind actual rpm. I have seen lag times of 1000-1500 rpm to be somewhat normal on hard accelerating bikes.
I would highly suggest learning a bit about how the ECU, Lambda sensors, specific interface software (TuneEdit/TuneECU), and dynamometers all work before you start blindly making changes. Today, a huge amount of information is available from just an internet search.
I hope this helps.
It is used to correct idle and cruise with the stock narrow-band Lambda sensor FOR EMISSIONS PURPOSES.
The narrow band sensor, only has a design range of 0.98-1.02 Lambda (14.2786 - 14.8614 AFR). Outside of this range it is not accurate, and the ECU doesn't even use the AF table corrections if cells are set below its range. This is why Wayne MacDonald at TuneBoy recommends setting the cells richer - to keep the ECU from altering the work done when mapping the rest of the tables where the Lambda sensor is normally used.
If you want to enrich the region where you are lean, modify the F tables or Fuel % Trim table at 100% TPS. The graph is only showing 100% TPS, nothing below. It is possible to be lean at 100% TPS, and rich or lean (or a combination) at lower TPS openings. With fuel injection, anything is possible - garbage in, garbage out... and all that. You have to test and tune all loads (TPS and MAP) at all engine speeds for full mapping.
Also, you need to understand that mixture ratios will change slightly when read with a wide-band Lambda sensor on a dyno run. Things like engine, oil, and air temps alter the way fuel is delivered to the cylinder, and how it is burned in the chamber. This alters the residual oxygen in the exhaust gases - which is what the Lambda sensor detects.
When performing a sweep test, the first part of the pull is also affected by the amount of acceleration compensation in the MAP fueling tables (L tables). When you first roll to WOT, the engine demands more fuel for acceleration under load. Getting this correct will help.
Also, be aware that there is a lag time built into the logged mixture ratio, and what is displayed on the dyno graph. The lag is mostly due to the time required for gases to travel from the chamber, to the end of the exhaust, then be pulled into the meter for testing. The faster the bike accelerates, the further the displayed ratio will lag behind actual rpm. I have seen lag times of 1000-1500 rpm to be somewhat normal on hard accelerating bikes.
I would highly suggest learning a bit about how the ECU, Lambda sensors, specific interface software (TuneEdit/TuneECU), and dynamometers all work before you start blindly making changes. Today, a huge amount of information is available from just an internet search.
I hope this helps.
JRCollings
.040 Over
Thanks Power-Tripp that certainly helps me at least!
The A/F tables are used to covert the numbers in the F and L fuel tables, which are volumes (V) to fuel amount (length of injector pulse): F=V/(A/F). If you increase V, you get more fuel. Decrease V, you get less fuel.
Except when the value in the A/F table is 14.57, in which case the ECU goes into closed loop and uses the O2 sensor to determine fuel. This table is TP versus rpm. The 14.57 values appear below 3800 rpm for TP less than about 10%.
Except when the value in the A/F table is 14.57, in which case the ECU goes into closed loop and uses the O2 sensor to determine fuel. This table is TP versus rpm. The 14.57 values appear below 3800 rpm for TP less than about 10%.
Power-Tripp
Turbocharged
I think you may be confused, and need to actually test this.
Outside of Lambda 0.98-1.02, and higher than 6% throttle, the AF table does nothing to add/subtract fuel to the F and L tables. Under these conditions, the ECU ignores the table, and the Lambda sensor output.
You can set all cells in the AF table at 10.0:1 at 10-100% TPS, and the engine will not run richer than set by the F and L tables.
Pig9r
Living Legend
Just curious, then why do they have values to 100% TP?
