What caused this fluctuating in AFR

[wesam]

I'm tuning my VE table i noticed that in some cells in my WO2 map that the maximum value reached at this map some times goes to 18 and the smallest value dropped to 12 !!
could any body told me what caused this issue ? is this normal if the average in this cell will be near the 15 ?
also i want to know what makes the commanded AFR different than the WO2 AFR

[ChipsByAl]

You might want to post your current tun file and a log showing this condition.
Al

[wesam]

here is my last log and tune file

[Chevy366]

I'm tuning my VE table i noticed that in some cells in my WO2 map that the maximum value reached at this map some times goes to 18 and the smallest value dropped to 12 !!
could any body told me what caused this issue ? is this normal if the average in this cell will be near the 15 ?
also i want to know what makes the commanded AFR different than the WO2 AFR
Can't see your log and tune on my phone , but wide-band AFR should mirror the commanded that is why we do the AutoVE process , to bring both to closer alignment with each other.
Commanded is what the PCM is wanting, WO2 what you are actually receiving , simply put.

[swingtan]

After a fairly quick look and putting it fairly bluntly, it would seem that the VE table is simply way off. However, there are a couple of other things that don't quite add up.


Your VE table looks to be set quite low in the high vacuum cells ( throttle closed and coasting down ), but the WB shows that you are consistently rich in these areas.
You are consistently seeing lean spikes on throttle opening, but normally you are running quite rich.


If you have modified the car according to your sig, then I get the feeling your fuel delivery is messed up and the ECm simply can't control it with the current settings. I can see that changes have been made to B4001{Injector Flow Rate} to compensate for the after market injectors, but it appears the values were just ramped up a bit and probably not matched to the injectors.

Another thing is that your Injector pulse widths never really drop below 2mS. Actually, I think this is the key as most of the "erratic WB AFR" occurs when the IBPW is stuck on 2mS. Your tune indicates that the minimum pulse width should be 1.27mS but for some reason, it's only dropping to 2mS. I'm not sure why this is happening though. Any chance you've had a failed flash or didn't wait the full 15 seconds after flashing in the tune?

Simon

[5.7ute]

Simon. The reason that the PW never drops below 2.0ms is that the min PW value plus the offset gives you IBPW.

[swingtan]

Which table does the offset ? B4005 ?

[wesam]

I always wait for 15 sec.
please i need help from some one
i need to keep the 80 lph injectors as i will go FI next year
but i don't know what should i do to tune it the right way
if some one could tell me the steps and what should try i will be glade for him
thanks in advance

[5.7ute]

B3701. If you add the .cax file attached to this post to your calibrations file, you will notice that B9021 is set to 1.398216ms. This plus B3701 will give you the 2ms IBPW.
This table has proved to be active during idle conditions & has caused 99% of the rich idle problems inherent with US calibrations that I have seen on here. In Australian Calibrations this is usually set much lower(around 1.1ms)

[wesam]

the biggest problem i have now that the low map from 15-50 does not respond to decreasing in the VE table i need to leaning the car at idle but it seems that what ever i did it will not go leaner than 13.5

[5.7ute]

the biggest problem i have now that the low map from 15-50 does not respond to decreasing in the VE table i need to leaning the car at idle but it seems that what ever i did it will not go leaner than 13.5

Whenever you hit a pulsewidth minimum limit that is what will happen.
If the injectors can controllably fuel at a lower PW you lower the min pw values. If not you will be stuck with rich idle & decel.
We really need some actual specs on your injectors if anyone here is to be able to help.

[swingtan]

5.7Ute, good work! looks very interesting.

Wesam, Read what 5.7ute and I are talking about....

Your tune is set to allow a minimum injector pulse of 2mS, which is too long with the larger injectors you have. This results in the loss of fueling control in the low MAP cells of the VE table. The shortest pulse the PCM will command is 2mS, but because your injectors now flow much more than the stock ones, you end up with way too much fuel.

If you take the CAX file that 5.7Ute has uploaded and unzip it into your Calibrations folder ( normally C:\Program Files\EFILive\V7.5\Calibrations ), you will be able to adjust the minimum settings. Simply "re-open" your tune file after adding the CAX file and have a look under "Engine Calibration - Fuel - Injectors - Parameters". There should eb a new option called "{B9021} Minimum Transient Pulsewidth". Set this to something lower, like 1.1mS and see if this helps.

A pint to note though, is that all injectors have a default "mechanical minimum pulse width" which is the time it takes for the injector to "mechanically" open and close. If you set the commanded minimum pulse width to a value below the injectors "designed mechanical limit" you and up with no fuel. This is because the injector doesn't have time to open before the electrical power is turned off by the PCM. To make matters worse, higher flowing injectors tend to also have a higher "mechanical minimum pulse width", which makes closed throttle tuning very difficult.

The way I would handle this is as follows....


Try the CAX file from 5.7Ute and see how low you can go on the minimum pulse width before the engine stalls from no fuel. If you have the specs on the current injectors, you should be able to find the minimum pulse width details.
Redo the Auto VE process and get the VE as close as possible with the injector settings. Use long logs when doing this ( as I'm assuming this is being tuned on the street ) at least 45 min per log but over an hour would be better. Also use some copious filtering to remove all transient data.
Once the VE is good for all values, but possibly not for low MAP, enable DFCO and have it come in fairly quickly. This will turn off the fuel in low MAP areas and effectively "mask" the rich low MAP cells in the VE.
Then revisit the VE table, this time filtering out all log data where DFCO is active.


This should help to get you in the ball park.....

Simon.

[5.7ute]

X2
Just make sure that if you want to use the default PW table(B4004), B4003 is set higher than B9021. B9021 is an absolute value where B4003 is an enabler for B4004.

[wesam]

OK i got it
all i know is my injectors are Siemens 80 lph
where could i find the minimum pulse width ?
also is it better to try 1.4 as an example first before going to 1.1 for the pulse width
also should i increase VE table 20% in the lower map so i will not be too lean before decreasing the pulse width ?

[wesam]

ok here is a link for the injectors i have if this could help
http://www.bmotorsports.com/shop/product_info.php/products_id/1589

[5.7ute]

OK i got it
all i know is my injectors are Siemens 80 lph
where could i find the minimum pulse width ?
also is it better to try 1.4 as an example first before going to 1.1 for the pulse width
also should i increase VE table 20% in the lower map so i will not be too lean before decreasing the pulse width ?

If they are anything like the 60lb injectors you could esily start with min PW around 1.1ms. Not having played with the 80's I cant say for sure though.
And yes, increase the VE table in the low map areas. Especially if you have been trying to lean it out unsuccessfully with autoVE. This will more than likely be way to low now where you were hitting that min pw limit.

[swingtan]

RE. The specs on the injectors..... Try this

http://siemensdeka.com/specsheets/FI114991.jpg

and

http://siemensdeka.com/specsheets/FI114991cs.jpg

Note that the minimum pulse width for "linear operation" is 1.9mS and that the "open" time is 1.3mS. So any pulse width under 1.3mS will result in no fuel and from 1.3mS to 1.9mS it will give a "less predictable" flow than over 1.9mS.

I'd look at the image and try and set up all the injector tables to suit ( assuming this is your injector ). I'd then go for a final min pulse width of around 1.7mS for starters to see how they react. Of course, given yo are playing with fueling, I'd keep a close eye on the WB.

Simon

[wesam]

thanks swingtan for the links
but i noticed that this calibration summery is for 39.15 psi
will this make any difference ? because the LS1 flow rate is 58 psi as i know

[wesam]

RE. The specs on the injectors..... Try this

http://siemensdeka.com/specsheets/FI114991.jpg

and

http://siemensdeka.com/specsheets/FI114991cs.jpg

Note that the minimum pulse width for "linear operation" is 1.9mS and that the "open" time is 1.3mS. So any pulse width under 1.3mS will result in no fuel and from 1.3mS to 1.9mS it will give a "less predictable" flow than over 1.9mS.

I'd look at the image and try and set up all the injector tables to suit ( assuming this is your injector ). I'd then go for a final min pulse width of around 1.7mS for starters to see how they react. Of course, given yo are playing with fueling, I'd keep a close eye on the WB.

Simon

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

[joecar]

thanks swingtan for the links
but i noticed that this calibration summery is for 39.15 psi
will this make any difference ? because the LS1 flow rate is 58 psi as i knowThe the flowrate conversion factor is sqrt(58/39.15)...

Edit: the spec sheet says 39.15 psi and the website says 43.5 psi...

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

[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....


The greater of B4003, B4004 or B9021
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.


Leave B3701 alone.
Leave B4003 alone.
Leave B4004 alone.
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/2010/01/svo-greentop-42-testing-at-3-and-4bar.html

[joecar]

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

[5.7ute]

wesam, for simplicity make B4003 lower than B9021. This will keep the default pulsewidth table from coming active at this time & confusing matters.
Also set B4006 small pulse threshold to 1.9ms.

[wesam]

why is my B3607 is set to 0.981 should i put it 1.005 or some thing equal to 14.7 to make it leaner at idle ?

[wesam]

will changing B3607 Open Loop Lean Limit (Idle) from 0.981 to 1.005 will leaning my commanded idle AFR from 14.36 to 14.7 ?
is this parameter limit the leaning idle what ever we change in the VE table ?

[5.7ute]

This table is the lean limit that the pcm can command in an open loop idle condition, no matter what any commanded AFR modifiers are trying to achieve.
Again this has nothing to do with the VE table. The VE table is an AIRMASS estimator. Not fuelmass.
In speed density mode (mafless) The pcm reads map & rpm, then looks up the VE table to see what airmass is present in the cylinder. This value is further modified by the charge temperature which is worked out from IAT,ECT & the blending factor. Giving you "CA"
While this is going on the pcm reads ECT & MAP (for a standard OS) or RPM & MAP (for a custom OS) & looks up the commanded fuel table."AFR" And also looks up manvac for the "IFR".
This is then used in a calculation for the injectors pulsewidth which is roughly IPW=CA/AFR/IFR*1000.
The result of this after combustion is your wideband or actual AFR.

[wesam]

ok i will rise it and try today maybe it will make the idle leaner cause i'm stock now at 14.2

[odd boy]

Injector size is too big for your application, that doesn't mean you won’t be able to do it, but it will be a bit harder.

I have a side suggestion, can’t u merge your mods in the signature section? It takes space of 3 replies!!!! Some parts are installed on most cars like MSD wires, Can catch...etc:)

[Chuck L.]

From the website: "These injectors flow 80 lbs/hr at 43.5 PSI ( 3 BAR )"
Doing the conversion, these injs are running at a flow rate of 92.37#/hr at 58psi. [4 bar]
As Joecar mentioned, check your actual fuel psi, and recalculate if it's not at 58...

[wesam]

Well finally after changing B3607 from 0.981 to 1.005 and after putting the B9021 to 1.1 instead of 1.3 i could have the idle AFR to 14.6 :)
thanks for every one
after i finish my VE i will turn the DFCO to fix the dec rich issue

[WeathermanShawn]

I have a side suggestion, can’t u merge your mods in the signature section? It takes space of 3 replies!!!! Some parts are installed on most cars like MSD wires, Can catch...etc:)

Agree..shorter the signature..more likely to want to read and respond. Wesam, know you are proud of your vehicle..you might want to condense it by line (see my sig).

Just a friendly suggestion from a fellow tuner/enthusiast..:)

[wesam]

Ok my friends the signature is shortened now
i hope this is better :)
always your opinions will be welcomed :)

[WeathermanShawn]

Looks good.

How do you like that electric water pump? How effective is at cooling the engine? Thought it might be nice to have one, but like everyone else..not spending as much money anymore on modifications..Curious as to its effectiveness and do you really gain any additional HP from it?

Thanks..

[wesam]

i don't know how much i gain from it because i put it when i installed my 408
for the cooling i didn't noticed any difference i think it will be good for 10 hp in the top end because the stock WP will make some load on the crank at higher RPM

[WeathermanShawn]

Thanks..

You have a very nice setup. Hope you get that Fuel Injector issue solved. Bet that 408 can really scream!

Good luck..

[joecar]

Good job on the sig...:cheers:

[swingtan]

Great to see the fueling is coming along nicely now. Post up some more logs when you get a chance.

Simon

[joecar]

+1 post more logs and any tune file updates.