AEM Ultimate Resource Thread>>>>

[slava]

Originally Posted by pacman3000gt

you have your microsetbits set that low?
I think mine is around 75ish.

as far as i understand the microsecond works as scale for the fuel map. the Raw fuel map values can be from 0 - 255 (which is one byte Hex 00-FF).
The raw value multipled by the microsecond/bit value to get a real timing for fuel. The lower the microsecond you can get the fine you can adjust the fuel (assuming the injector size did not change). I think the basic rule is to keep your raw max value close to 255.That allows to lower the microsecbit and rich the best resolution of fuel adjustment.
correct?
here are the example:
1. the raw fuel number is 200, when you +/- 1 you are adding/removing 0.5% of the fuel.

2. the raw fule number is 10. when you +/-1 you are adding/remvong 10% of the fuel.

[pacman3000gt]

Running a lower microbitsec does give you better 'fine-tuning' control over the injector pulse width. Your interpretation on the correlation between mBitSec and the fuel map is right.

BUT... I know my densos don't like going down that low. If you have managed to get the microbitsec down that low without a hitch then... that's definitely the best option. But some injector cannot operate too well below a certain point.

Just my .02

[Renner]

Originally Posted by slava

Related question the the board...
Putting PTE750 which should flow something aroudn 720. Currently running 360.
Instead of making injector change in the fuel map and rescalling it looks like better way is to change MicroSecBit . i have 40 now and will change it to 20.

Thoughts?

I take it you are running a boost comp map?

20 is probably too low, you might not have enough adjustment range before your raw value is above 255 (which is bad).

I typically use 40 msec/bit for the hybrid boost comp maps I do, it gives a nice balance between resolution and range for cars with larger injectors such as 850's or 1000's.

Just use the injector change function when you put your 750's in, it works pretty well to get you initially on target.

[slava]

Originally Posted by pacman3000gt

you have your microsetbits set that low?
I think mine is around 75ish.

I looked at the map you sent me before it had microsecond set at 75 and the max value in the fuel map is around 67.
I rescale the map which increased max raw value in the map to 204 and decresed microsec to 25.

You might want to look at it.

[slava]

Renner, I agree.
yes, boost comp which minimizing the diff between Min and Max values in the fuel map.
yes, the max value should not be 255 to leave some room for adjustment. Looks like rescaling function gives good results.


Pacman, correct me if i am wrong but microsecbit has nothing to do with type of the injectors.

[pacman3000gt]

Well other than the ratio for the pulse width ... no it has nothing to do with the injectors

I always assumed that running too low a mBitSec would not be too healthy either. What recommended minimum operating pulse width is acceptable for most injectors? Is there no minimum limit? Is it just a range issue?

What Renner and you point out about the adjustment range and max raw value of 255 definitely makes sense. I'll definitely look into rescaling my mBitSec. But it's kinda hard to change something that has worked for so long

[mjannusch]

You can run the "Optimize" option from the fuel table's right-click menu which should optimally scale your msec/bit for you. Take a good look at your fuel map in graph mode to make sure it visually still looks like it did before, sometimes the optimize function really screws up the map (not sure why).

Seems like the optimize function tries to get you in a range of 50 to about 225 or so for raw values, which is a pretty good range. Do this after you've got fuel pretty well dialed in though. Then tweak a bit more to get your A/F dead on where you want it.

[mjannusch]

BTW, after an optimize, my msec/bit is at 20 as well. Started at 75 pre-optimize. 680cc injectors at standard fuel pressure.

[Powertrip]

I have a question for you guys. I don't have a very good AEM map currently, but my air fuel ratio is good and stable when at idle or when the throttle is pressed very, very, very slowly, but the car goes very lean (AFR > 20) when I press on the thottle much quicker (worse the more rapid the change). Sometimes it is so bad that I can bearly rev the engine.

The EMS is not able to provide enough fuel quickly enough with increased throttle. What settings do I change to correct this?

[mjannusch]

Accel fuel tables. Either TPS-based or Load-based, your choice. You can do both, but typically one strategy is sufficient (I use TPS).

Some more info:

http://forum.aempower.com/bbs/viewtopic.php?t=11026