"Target AFR" not showing the correct fuel map table value?

[kc427]

Hi all,

As far as I know, the "target AFR" on EVOSCAN, supposingly, it would show the target AFR from the fuel table that ECU expected.

Next step, I changed the High Fuel Map 1 and 2, and set the idle AFR to a little leaner, ie, 15.6. After that, take the log so that at idle, Engine load is around 20-30, and RPM is around 650rpm. However, the "target AFR" is still 14.7, not 15.6 that I set in the fuel map table. Does anyone know why? It seems that the target AFR is "locked" to 14.7. I attached the full log CSV you can check.

High Fuel Map 1 & 2 that I modified like this:

Summary:

	RPM	engine load	AFR in High Fuel Map 1 & 2 table	target AFR from Evoscan
at idle	around 650	around 30	15.6	14.7
fast idle	around 1800	around 20-25	15.4	14.7
fast idle	around 2300	around 20	15.4	14.7
Just release throttle (logID 1055 from the log csv file)	around 2200	around 10-15	15.4	15.4

The target AFR seems correct only when I release throttle. Other than that, ECU keeps targeting AFR to 14.7.

 

[GLen20]

I don't know for sure, but maybe running in Closed loop at idle? This would drive 14.7 and override fuel tables.
Can't quite remember off the top of my head conditions for enabling closed loop, but maybe investigate this. (I suspect it is probably the cause).
I'd find a way to disable closed loop and see if that gives you control.

Probably unrelated but worth mentioning, I was told by TME Steve once that the fuel maps numbers are not true representations of AFR figures. They are just numbers used as a tool, and the true AFR is derived from a Wideband.

You're not running a tune are you? I went changing my Timing numbers one day and got zero change in data. Turns out my custom tune was based on KennethsMods and the AFR and Timing tables were stored in another part of the ECU code and my ECU Flash wasn't looking at those tables at all.
If yours is tuned, could also be the answer...

 

[kc427]

I don't know for sure, but maybe running in Closed loop at idle? This would drive 14.7 and override fuel tables.
Can't quite remember off the top of my head conditions for enabling closed loop, but maybe investigate this. (I suspect it is probably the cause).
I'd find a way to disable closed loop and see if that gives you control.

Probably unrelated but worth mentioning, I was told by TME Steve once that the fuel maps numbers are not true representations of AFR figures. They are just numbers used as a tool, and the true AFR is derived from a Wideband.

You're not running a tune are you? I went changing my Timing numbers one day and got zero change in data. Turns out my custom tune was based on KennethsMods and the AFR and Timing tables were stored in another part of the ECU code and my ECU Flash wasn't looking at those tables at all.
If yours is tuned, could also be the answer...

My ROM is stock only, not tuned, so I don't know why the "target AFR" is 14.7, and not the value from the table at idle at closed loop. Or, as you said, when in closed loop, it would be only 14.7 regardless the map table? Also, I suspect whether my MAF is too old and the data is off-ed, eg, the air flow Hz, etc.

I attached a log file that I almost enable all the necessary items in the log. Noted that the 2byte Air Flow probably wrong.

 

[Blackbandt]

You had according to other post a wideband lambda sensor retrofitted or ? If so, what shows this the when driving?

 

[kc427]

You had according to other post a wideband lambda sensor retrofitted or ? If so, what shows this the when driving?

Yes, I did the wideband logging retrofitted after this. Right, I will find sometime to do the full logging again, together with the wideband logging.

 

[kc427]

Just got a new log with wideband AFR logged, and it seems that no matter slow idle or fast idle, the actual AFR is around 14.7, and regardless the fuel map table data I flashed into ECU.

 

[GLen20]

Have a look at a log I did a while ago.
When conditions have been met for closed loop, target AFR reverts to 14.7

You can see as soon as I give it some throttle / load, it switches to the fuel map, so I reckon that is a good indication when is coming out of closed loop and switching to open loop.

When I am cruising at 60, after a little while, its switches over to closed loop and target AFR switches to 14.7

So I think this logged 14.7 AFR is a actually a good indication when the car is running off the O2.

If you disable closed loop, I reckon you'll get control of the AFR everywhere.

(Ignore the negative timing numbers - that's my pops 'n' crackles doing their thing )

 

[kc427]

Have a look at a log I did a while ago.
When conditions have been met for closed loop, target AFR reverts to 14.7

You can see as soon as I give it some throttle / load, it switches to the fuel map, so I reckon that is a good indication when is coming out of closed loop and switching to open loop.

When I am cruising at 60, after a little while, its switches over to closed loop and target AFR switches to 14.7

So I think this logged 14.7 AFR is a actually a good indication when the car is running off the O2.

If you disable closed loop, I reckon you'll get control of the AFR everywhere.

(Ignore the negative timing numbers - that's my pops 'n' crackles doing their thing )

I did the log another way, I did that without the car moving, with the ROM with fuel map on post #1, ie, fuel map expecting 15.4 when low engine load. I don't know when it is in closed loop, ECU uses constant 14.7, and ignore the fuel map 15.4. Or, somehow, there are some fuel enrichment added.

To be more exact, I want to see I can change AFR on the fuel map to around 15.4, 15.6 when fast idle and low idle, so that during emission test, or MOT, it could be a bit leaner, instead of 14.7.

 

[GLen20]

I did the log another way, I did that without the car moving, with the ROM with fuel map on post #1, ie, fuel map expecting 15.4 when low engine load. I don't know when it is in closed loop

This is my point.
You did the log with the car idling and at low engine load. So therefore all the conditions have been met and the car is in Closed Loop and the fuel table gets ignored. The car is showing you this by displaying in the logs that it is looking to run at 14.7.

I want to see I can change AFR on the fuel map to around 15.4, 15.6 when fast idle and low idle
So the only way you can get control is to change the conditions for when the car engages open loop, so that it is not running in closed loop at idle

If you explore your ROM, you can see the conditions that have to be met for open loop mode to be engaged.

Examples:
If the Throttle Position exceeds these numbers at these RPMs:

Or if Load exceeds these values at these RPMs:

There may be more (I don't have the correct Def files on this computer).

So your car is running at 24-25 Load at idle.
You could change the 500rpm & 750rpm Open Loop Load table items (on both tables) to 20%. Therefore load on the engine will be exceeding this at these RPMs and the car will therefore kick into Open Load at (and between) these RPMs. Also probably between 750 and 1000rpm as well. as it interpolates between the RPMs as well.

Then log it to check and see what happens.

*Disclaimer*. This is only my advice and understanding and anything you do with your car and any damage is at your own risk.

Let us know how you go and if it works.

 

[kc427]

This is my point.
You did the log with the car idling and at low engine load. So therefore all the conditions have been met and the car is in Closed Loop and the fuel table gets ignored. The car is showing you this by displaying in the logs that it is looking to run at 14.7.

I want to see I can change AFR on the fuel map to around 15.4, 15.6 when fast idle and low idle
So the only way you can get control is to change the conditions for when the car engages open loop, so that it is not running in closed loop at idle

If you explore your ROM, you can see the conditions that have to be met for open loop mode to be engaged.

Examples:
If the Throttle Position exceeds these numbers at these RPMs:

View attachment 65200

Or if Load exceeds these values at these RPMs:

View attachment 65202

There may be more (I don't have the correct Def files on this computer).

So your car is running at 24-25 Load at idle.
You could change the 500rpm & 750rpm Open Loop Load table items (on both tables) to 20%. Therefore load on the engine will be exceeding this at these RPMs and the car will therefore kick into Open Load at (and between) these RPMs. Also probably between 750 and 1000rpm as well. as it interpolates between the RPMs as well.

Then log it to check and see what happens.

*Disclaimer*. This is only my advice and understanding and anything you do with your car and any damage is at your own risk.

Let us know how you go and if it works.

Understand, let me find some time and try your suggestion.

 

[kc427]

This is my point.
You did the log with the car idling and at low engine load. So therefore all the conditions have been met and the car is in Closed Loop and the fuel table gets ignored. The car is showing you this by displaying in the logs that it is looking to run at 14.7.

I want to see I can change AFR on the fuel map to around 15.4, 15.6 when fast idle and low idle
So the only way you can get control is to change the conditions for when the car engages open loop, so that it is not running in closed loop at idle

If you explore your ROM, you can see the conditions that have to be met for open loop mode to be engaged.

Examples:
If the Throttle Position exceeds these numbers at these RPMs:

View attachment 65200

Or if Load exceeds these values at these RPMs:

View attachment 65202

There may be more (I don't have the correct Def files on this computer).

So your car is running at 24-25 Load at idle.
You could change the 500rpm & 750rpm Open Loop Load table items (on both tables) to 20%. Therefore load on the engine will be exceeding this at these RPMs and the car will therefore kick into Open Load at (and between) these RPMs. Also probably between 750 and 1000rpm as well. as it interpolates between the RPMs as well.

Then log it to check and see what happens.

*Disclaimer*. This is only my advice and understanding and anything you do with your car and any damage is at your own risk.

Let us know how you go and if it works.

Tested and it works. I set Open Loop Load 1 and Open Loop Load 2 for 2000rpm - 3000rpm with 15.0%, so, ie, more than 15% will change to open loop. After that, AFR reads about 16.4, although map table is about 15.4. It's a good sign that it is in open loop and not yet 14.7. Will try to get a full log next time.

 

[GLen20]

Good to hear!