M4 Pro too rich at idling unable to reduce

[stevieturbo]

the dead time is 12v ~1140, 13v~1060

I would suggest that you need to measure that yourself.
if you wind that right back to zero, and wind back the fueling cells at idle to zero, then it should not be running rich.[/quote]

Surely if the fuel map is at zero, the car should not be running at all ?

He says he has a pulse width of 0.2ms with the map at zero. Surely that makes no sense ?

[Holmz]

the dead time is 12v ~1140, 13v~1060

I would suggest that you need to measure that yourself.
if you wind that right back to zero, and wind back the fueling cells at idle to zero, then it should not be running rich.

Surely if the fuel map is at zero, the car should not be running at all ?

He says he has a pulse width of 0.2ms with the map at zero. Surely that makes no sense ?[/quote]

I am not a tuner...
But it seems like the injection open time is a function of the commanded open time and the dead time.
I think the flow is a function of the voltage, dead time, open time, and fuel pressure.

So if he is running too rich:
Then setting the fuel pressure to sensible levels, and reducing the commanded open time make sense.
If it is still too rich, then I suspect that the dead time might not be optimal.

[Blu302]

On the M800(guess the same for M4) the ECU applies deadtime to injector, even when no fuel is called for(logging shows this). So, if the deadtime is too large the injector will open when the ECU thinks it will not open from deadtime. The deadtime of an injector is critical to tuning because fuel pressure and voltage affect deadtime, changing the whole tune.

I have high impedance injectors where 12v is 880 and 13v is 740. Your values sound way too high for low impedance.

[Holmz]

... Your values sound way too high for low impedance.

I agree w/Blue.

It would probably be worthwhile to measure the dead time and get that sorted out first.
I suspect that the cells to the right at 14V and 14.5V need to be correct.
Having the 12V and 13V cells correct is only of academic interest if the car actually starts up.

[wenya]

Hi Guy

Many thanks for the input

will try to see what it happen .

we are going to race at this sunday with other race car , so it busy this week unable to test it yet .

will update on next week

Regards

[MarkMc]

As has been stated the main fuel table is one thing, if you set it to zero then the only thing contributing to the fuel going into the engine is the Battery Compensation (dead time). If the engine is running too rich then I would first check that the injecotrs are not full of rubbish....this can sometimes hold them open. Next definitely check your fuel pressure at the rail with something you definitely know is correct. Then it would be best to get the injecotrs properly tested for Battery Comp.

It does sound unusual to me that you can reduce the fuel table to zero and still be too rich, even for 1000cc injectors. If you press "t" for trims in the M4 and M48 you can see everything that is going into the actual pulse width calculation. Check this with the engine running and let us know.

[wenya]

problem fix

after reduce the injector dead time to 720@15v .

now can idle at A/F 14 or 15 with 43psi of fuel pressure .

Thanks Guy

will post the dyno chat after done the car .