What caused this fluctuating in AFR

[wesam]

joecar i did not get your point, do i have to multiply all the given data in swingtan post by sqrt(58/39.15) like the injector pulse width voltage adjustment ? or this is just for the flow rate table ?

[swingtan]

i think there is some thing wrong here because in my tune my minimum pulse width is set to 1.276591 so its under 1.3 and there is still fuel !!!
could you illustrate this point to me

I think you missed the whole "CAX" file bit. Here's a summary....

Min Pulse Width is calculated from the following tables....

1. The greater of B4003, B4004 or B9021
2. Plus B3701

In your tune, you have...

• B9021 = 1.398216 mS
• B4003 = 1.276591 mS
• B4004 = 1.276591 mS
• B3701 = 0.577505 mS ( low MAP @ 13.5 volts ) or 0.623098 mS ( low MAP @ 13 volts)
  

So your effective min pulse width is...

1.398216 + 0.577505 = 1.975721 mS @ 13.5V
1.398216 + 0.623098 = 2.021314 mS @ 13V

If you check you logs, you will see the final minimum pulse width commanded via the PID "GM.IBPW1"

Simon.

[wesam]

i did not miss the CAX file i install it and now i could modify B9021
so now i will do the following and correct me if i'm mistaken
1- i will copy the injector pulse width voltage adjustment B3701 values from the sheet you post it to the table in my tune file which is 0.903 @13V and put it instead of 0.4XX - 0.6xx @13v
but if did this will increase the min pulse width because 1.398216 + 0.903 = 2.301216 ms
and as i understand from you we need to decrease the min pulse width not to increase it
so i think i have to decrease B9021 from 1.398216 to 0.797 so the total of B9021 + B3701 = 1.7 ms
is this correct ?

[wesam]

please read my last post and correct me if I'm mistaken

[joecar]

joecar i did not get your point, do i have to multiply all the given data in swingtan post by sqrt(58/39.15) like the injector pulse width voltage adjustment ? or this is just for the flow rate table ?

No, just the rated flowrate to obtain the flowrate at 58 psi...

Your B4001 table says: IFR @ MANVAC=0 is: 7.8828 g/s = 62.56 lb/hr <-- this is for 58 psi rail pressure.

But your injectors are rated to flow 80 lb/hr @ 39.15 psi...
so at 58 psi they flow 80*sqrt(58/39.15) = 97.37 lb/hr = 12.2688 g/s

Your IFR table is way different than what your injectors actually do.

[wesam]

swingtan I'm still waiting for your answer

[swingtan]

OK, we seem to be going in circles a little bit.....

If you simply want to "make it work" without getting too involved with the injector settings, try this.

1. Leave B3701 alone.
2. Leave B4003 alone.
3. Leave B4004 alone.
4. change B9021 to something around 1.1mS

Because the the value set in B9021 is added to from B3701, the final pulse width will still be above the 1.3mS minimum. It'll be in the non linear area of the injector operation, but you can't help that.

This should return some control over the fueling in the low MAP areas as well as idle, remember to richen up the VE cells as they look quite lean ATM.

Moving forward, you might want to use the specs for the injectors to build up the correct values for all of the tables. You will need to do some work on getting the right values for th tables as the data isn't given in the same format as it's needed for the tune file. You might get away with just reducing B9021 though.

Simon.

[wesam]

Thanks Simon
i appreciate your help
i will try with B9021 today and i will inform you what will happen thanks again

[redhardsupra]

The the flowrate conversion factor is sqrt(58/39.15)...

But do measure your rail pressure to make sure it is 58 psi, and that it stays steady when you initially snap throttle open.

at the risk of sounding like a broken record, do NOT assume that your rated pressure might be 39.15psi, or any other magic number. have it flowed at YOUR pressure, and get rid of all assumptions altogether. Here's why:
http://redhardsupra.blogspot.com/201...-and-4bar.html

[joecar]

Marcin, good point, we've seem too many different "rated pressure" values.