Q in the fuel table off alot

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Q in the fuel table off alot

Postby Mobne on Thu Apr 14, 2022 7:03 am

I just noticed that the Q funktion in the fuel table messes upp the tune.

If i have a valute of about "20" in the table for lambda 1 and press Q it will increse it to like 35 and that is really rich.

What causes this? Where should i start looking to find the cause of this error?
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Re: Q in the fuel table off alot

Postby NathanB on Thu Apr 14, 2022 8:56 am

There are mulitple causes for this:

- If your way off on the load site target, particularly with tables that have large steps between site can cause highly inaccurate adjustments. You should only adjust with the Q function when the square is green in the crosshairs.

load site target.png
load site target.png (328.53 KiB) Viewed 692 times


- You can also run into issues if you are doing it on transients where fuel film is currently in effect.

- You need to ensure that you fuel mixture aim is targeting the lambda you are trying to run.

- If injector calibrations, or sensor calibrations are inaccurate, or completely wrong, then the fuel model calculation will be incorrect

- If the ambient estimate, fuel temperature estimate, or fuel pressure estimate/regulator type are set wrong, this can cause calculation errors.
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Re: Q in the fuel table off alot

Postby Mobne on Tue May 24, 2022 2:58 pm

Im tuning with multi throttle tuning method where the main fuel table is the map estimate and engine efficiency is 100% on all loads.

Is this what causing it not to work?
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Re: Q in the fuel table off alot

Postby NathanB on Tue May 24, 2022 4:21 pm

The Q function still works correctly when using the inlet manifold pressure estimate mode, provided you are using V01.11.0007 or newer GP firmware.

The interaction of the efficiency mode and estimate mode can the shape of the table greatly, as can what sensors are fitted to the engine, and what items are running off estimates.

For example, if you have a fuel pressure default value that is drastically different to what the fuel pressure is, or you have the regulator type set wrong (when not using a sensor, or when the sensor has a diagnostic error) this can skew the values.

If you are using the q function whilst the engine is in transient, this can cause a much larger value to be calculated than required. The Q function should be used in steady state and centred on a load site for maximum accuracy.

Are you referencing the crosshairs whilst using the Q function? Depending on how close your load sites are together, you might be attempting to calibrate a load site while you are a long way off where that load site value relates to (ie. if your throttle position axis is in 10% intervals, and you are calibrating a 10%TP load site at 15% throttle)
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Re: Q in the fuel table off alot

Postby Mobne on Thu Jun 02, 2022 5:59 pm

Fuel pressure is correct and the regulator setting also.

I just tested q on idle and it adjusted really rich.

Maybe it does not work on idle?
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Re: Q in the fuel table off alot

Postby NathanB on Thu Jun 02, 2022 8:54 pm

It will work anywhere providing the all the influencing channels are set up correctly, and I have tuned many cars using this method. The V8 supercars in Australia are also tuned and run on this method.

Map estimate tuning.jpg
Map estimate tuning.jpg (663.46 KiB) Viewed 409 times


The MAP estimate tuning method for individual throttle bodies or applications where a MAP sensor is not utilised is a lot less forgiving on anything set incorrectly compared to when a MAP sensor is used. If any of the following items are set incorrectly you can have bit issues with the calculations:

- Engine Displacement
- Engine efficiency mode
- Engine load normalised mode
- Fuel properties
- Injector location
- Fuel injection timing
- Inlet manifold pressure mode
- Inlet Pressure estimate mode
- Airbox/Ambient pressure sensor calibrations
- Fuel pressure sensor calibration, estimate or regulator setup
- Any fuel volume trims or compensations active
- Incorrectly tuned or setup fuel film
- Efficiency table not set to 100%
- Not enough resolution in the estimate table in the area of tuning
- Not being well centred on a load site/crosshairs when using quick calibrate
- Incorrectly set cooling charge gain
- Using quick calibrate in a transient instead of a relatively steady state condition
- Injectors resources assigned wrong
- Firing order set wrong
- Wrong injector calibrations
- Fuel mixture aim set wrong
- Active fuel mixture aim table is not the main, so target lambda is incorrect


The complete fuel calculations tab under 7. Monitor > 4. Complete fuel calculations can give some great indications of any potential issues in a calibration, or if a trim/comp is set wrong.

There are so many possibilities that could cause the issue it is possible to do more than speculate at least without a config, and ideally logging. Also be aware that not all custom firmware/partner packages will necessarily support the map estimate tuning method.
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Re: Q in the fuel table off alot

Postby SDean on Fri Jun 03, 2022 8:49 am

Whch Firmware are you using?
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Re: Q in the fuel table off alot

Postby Mobne on Fri Jun 10, 2022 2:52 am

m1 tune 1.4.0.286
Firmware 01.11.0041
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Re: Q in the fuel table off alot

Postby David Ferguson on Fri Jun 10, 2022 3:48 am

Have you reviewed the items in Nathan's list?

Tell us more about how you are tuning, I would like to hear details about things like this:

What RPM & Throttle Position are you attempting to tune?
Were the RPM & lambda values stable?
What was the lambda value when you pressed the Q key on the 20 cell?
What was the current Fuel Mixture Aim?
If you adjust the cell manually to get the Lambda value on target, what does the value change to?

What are your RPM breakpoints around this cell?
What are the values of the RPM cells adjacent to the cell you are tuning?
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