immediate fuel accel

[Lip]

I use Accel ign retard to soften the hard beginning of acceleration. But I also tried without. It has no influence on the lean spikes.

Just some questions of interest: When or at what motorposition does the m800 definitely close fuel calculation for a defined cycle?
Is this moment depending on fuel timing?
Is there a difference using fuel timing on basis of end or starting of injection

I will increase logging rates.


Thanks Lip

[asaparrat]

Hi all, I think you have a lean map before you do the acceleration (about LA .97), try tho get there La .88 or .86, Maybe you have the injector far away the cylinder, I have tha same problem in TC 2000 here in Argentina, and was solved with the transitories rich map (between 0 and 80% tps, .87 LA), and a very complex accel enrichment compensations, Good luck!!
Regards
Alejandro

[RossB]

The calculation for fuel requirement is continuous right up to the point at which the injector opens.

For port injection we always use end of injection timing because the optimum timing for the injectiion event is a function of inlet valve closure (and air speed through the port). As injection duration time can vary dramatically if you were to use start of injection timing it would be very difficult to achieve the best injection timing under all conditions. In a direct injection engine (diesel or gasoline) the optimum injection timing is a function of the start of the combustion process so start of injection timing is more appropriate.

Alejandro makes a very valid point regarding injector location. If you have an injector located a long way from the valve you may have difficulties getting good throttle response when using a lean steady state mixture. You could test this quite easily by making the base mixture richer with a trim and repeating the test.

[AlanB]

I would suggest repeating the tests with increased logging rates as it is virtually impossible to say what is going on when the logging rate is 20hz (or less) and the throttle accel is of the order of 50ms.

Try logging rpm, TPOS, la1, fuel accel, accel rate of change, base PW, inj duty at 50hz minimum and then have another look.

[Lip]

Dear all,

thanks very much for assistance.
The injectors are installed close to the cylinder heads. I am using a lean mapping (~ la 1) for low throttle positions and < la 0,9 from 70-100%. A solution will be to make it richer.

It will take few days but I will repeat the tests with higher logging rates and different mappings.

[Marc]

Alejandro makes a very valid point regarding injector location. If you have an injector located a long way from the valve you may have difficulties getting good throttle response when using a lean steady state mixture. You could test this quite easily by making the base mixture richer with a trim and repeating the test.

Hi RossB,

I read this issue that is more like my M800.

The defferent is the injector far from the port after the throttle.

I have multi throttle syetem.

When 0~10%tps la=1, 10~100% slowly from la= 1 to .87 .

I have map the main fuel table by these LA .

No matter I set the accel parameter , it always lean spike and a little improvement.

As you say in quote, I need try to set LA richer in idle from tps 0% (I will try LA .87)

Or begin from tps 1% to set richer base fuel map.

Please provide some suggestion.

BTW, the help in MoTeC say sync position ideal value is 20~80%.

But my sync pos is 87%.

Does it work normal for accel reponse?

My injection timing is 270 ,1000 rpm.

Very appreciate.


Marc

[Martin]

What is the value under
ADjust>General Setup>Miscellaneous Setup>Accel Threshold?

[Marc]

Hi Martin,thanks for the help

My Accel Threshold is 50 units/sec.

Setup value:

Accel calmp
1000
50

Accel decay
1000
15

Accel sensitivity
1000
100

I only try from idle.

Please give me some suggestion.

Thanks all.

Marc

[Martin]

Make accel threshold lower for the accel to work for smaller TP ROC values. This will make it activate accel fuel earlier as it reacts at a smaller number, (quicker)

[RossB]

Martin has made a good suggestion regarding the accel threshold try droping it to about 25.

You need to log the channel "Accel Fuel" so that you can see in detail what the accel enrichent is doing. ALso you should log your Lambda channel at a higher frequency and reduce the filtering on the Lambda input. You can do this in the input setup by changing the filter value from "8" to "1". You only need to filter this channel if you are using closed loop lambda control.