xfi tuning help!!!

thenash79

Member
Joined
Jun 26, 2004
i'm new to fast,trying to set up tune.i have good base program from vendor which was great on same combo,on know every car is different but i have tried several gct files.my problem is i have to pull so much out of my ve table to get o2 correction even close.in all the gct files i have, idle to transitional ve #'s are 30 to 55ish range .i have to pull this range down to almost single digits to be close to my target afr .i have checked all enrichment tables ,all around zero,all sensors look good,all parameters look good as far as injector size,displacement,map bar,etc...why should my ve table be so different with same combo?heres my combo ,.20over with caps,k1 rods ,champion unported aluminum heads,around 214/214 roller(may be wrong it's been a while),ported ebay headers,ported stock intake,70mm tb+doghouse,large frontmount w 3in piping,3 inch dp,test pipe,3in exhaust,83's,accufab adj reg,double pumper,ptim70mm w .82 exhousing,xfi,4inch intake,and the list goes on....

vender is more than willing to help but i want to play tonight but don't want to bother him.
1.are u supposed to tune in open or closed loop?if open there is no o2 correction to look at.
2.at idle my ve wants to be set a single digits,in all other gct files its around 30 to 40.i have adjusted throttle blades so iac is 15 to 25.all this is done warmed up around 160deg.fuel pressure set at 43 with hose off,and other pump is coming on around 10psi.
 
Since you're starting off with a new tune for your application, I'd start off tuning in closed loop. This will help you ensure that you don't have your tune too lean under boost. Make sure that your target WOT A/F table is around 11:1 AFR under high boost.

It is odd that your VE table has to be leaned out so much. Most of the ones that I've tuned with combos similar to yours end up around 35-40 at an idle on the VE table. I'd double check the accuracy of the FP gauge and have the injectors flowed to make sure that they flow what they are advertised.

Good Luck.
Kevin
 
my program looks good as far as target afr from what i've seen in the other gct's.your right my gauge may be off.its a good gauge but even the million dollar snapon gauges go bad.tomarrow i am going to get another gauge and see whats up.if not i will cut the pressure down a couple lbs to see if the ve table gets close.i just was set on some variable in this program being a little off.I have read soo much in this forum about tuning in open loop but there is no o2 correction,my program is setup on closed loop.thanks for your help,i'll let u know what it was:smile:
 
Check your injector opening time under:
view
system configuration
operational parameters

Moving this value down will lean it out on the lower cells alot.... causing you to be able to raise the base VE numbers considerably in the lower cells. It changes less the longer the injector pulsewidth is... for instance....

injector opeining time is set to .9 mS ..... then you change it to .4 mS. That is a change of .5 mS. If your idle pulsewidth is 5mS ... you basically just leaned it out by 10% at idle..... BUT..... when the injector pulesewidth goes much higher.... it still only moved it .5 mS....so if the injector pulsewidth was 50 mS..... .5 mS ... is only 1% that you leaned it out...... make sense?

In summary... this changing of the injector opeining time has a much higher change (% wise) on the lower parts of the table.... the further up the table... and to the Right... the less difference it makes.

IMHO... you want to play with the injector opening time until you can get the lower left cell (in the base VE table) while idling.... into the 20-30 range......once you get there.... you need to really start tweaking the base VE map while cruising... then some short throttle bursts.... then start datalogging... and tweaking the cells based on the amount of O2 correction that is going on.

HTH
 
ok checked pressure with a know good gauge,its dead on 43 lbs with hose off and 38ish with it on,my injector time is .9,i will start playing with that,anyone think injectors are 95's? mine are all black and say siemens deka 3105.i am also going to try to back fuel pressure down to see if i can get it close,but i still think somethings a miss,same combos ,same tunes,and so much richer.
 
looks like i got 83's,i cut the fp down to 30lbs with line off,afr went from 9.5 to 1 to 10.1,i reset pressure and cut the pulse with down to .4 like u said,afr went to 11.2 right off the bat.i then cut couple % on ve table ,looks good sounds good,im about the lower 30ish range.Is it common to cut that much pw.i am still curious as to why my combo doesn't like fuel,guess i will get better gas milage:) i am going to take her for a ride and try to set the rest of the ve table up.
 
also forgot my map readings are mid 40's while idling and load is showing 42%,this look right?thanks for everyones input!!
 
looks like i got 83's,i cut the fp down to 30lbs with line off,afr went from 9.5 to 1 to 10.1,i reset pressure and cut the pulse with down to .4 like u said,afr went to 11.2 right off the bat.i then cut couple % on ve table ,looks good sounds good,im about the lower 30ish range.Is it common to cut that much pw.i am still curious as to why my combo doesn't like fuel,guess i will get better gas milage:) i am going to take her for a ride and try to set the rest of the ve table up.

I wouldn't cut the fuel pressure... I would leave it alone and do the tuning with the laptop.... fuel pressure tweaking is old school... and changes the MAP everywhere. IMHO... the fuel pressure should be run up to say 43 psi with the line off... and start tuning from there with the laptop...

I assume your XFI is set to the right injector size?

Report back...
 
also forgot my map readings are mid 40's while idling and load is showing 42%,this look right?thanks for everyones input!!

Key on... engine off.... "bubble" on Base VE table should be on the far left.... about a third the way up..... MAP should be close to the 100.... as soon as you crank it.... the bubble should fall down to the bottom cell... all the way to the left... This would indicate your map sensor appears to be functioning normal.
 
Siemens 3102 = 55#
" 3105 = 83#
" 3145 = 72#
FWIW:
XFI manual:
"6.2.6 Injector Opening Time (ms)
You should not have to change this parameter with most popular engine applications. Always start at 1.0 ms".

Back under my rock...
 
i only cut the pressure to see how much the afr would change,i would have to set the fp at 15lbs to get my afr right,something else is wrong.map shows 100kpa and the bubble does what u said on startup.i do have 83's in the car from what the #'s state.the only way i can get this afr even close is to cut ve #'s down from 30's to single digits or cut the injector pw down to .4ish range,program was set at .9 and was the same on all the other 4 gct tunes i have for simalir combo.i don't feel comfortable hacking a program up so much that should be close right off the bat with my combo.something is not right,i'm going to go through the pids again.
 
forgot to say my parameters look good as far as injector size,displacement,etc...thanks again guys!!!
 
Siemens 3102 = 55#
" 3105 = 83#
" 3145 = 72#
FWIW:
XFI manual:
"6.2.6 Injector Opening Time (ms)
You should not have to change this parameter with most popular engine applications. Always start at 1.0 ms".

Back under my rock...

Don't do back under your rock....stay and help

One of the premier XFI turbo Buick guru's told me about adjusting injector opening time....

As I see it... right or wrong....you don't want your Base VE table to be too low or too high.... cause the computer has to have a range to work with to do the closed loop O2 correction.....

thenash79 said:
i have to pull this range down to almost single digits to be close to my target afr

If these cells are near 0..... the ECM can't pull alot of fuel out before it runs out of values to adjust too..... same thing would happen if the values were too high....it couldn't add enough fuel to get to the target AFR.... because there wasn't enough range in the table....

My point was there is a way to get the lower values to come up.... the fact the manual says "You should not have to change this parameter with most popular engine applications" suggests that occasionally you do....

Hence... why I asked if the XFI had the correct size injector set in the parameters....
 
Are you trying to idle in closed loop?

Sometimes upping your RPM limits for closed loop taking idle correction away from the ECM is a good option.
 
i don't want to be the oddball with a low injector pw,i don't want to be that guy;) i want to figure out what i have screwed up or whats wrong with my program,even off idle this thing wants me to rape the ve table,i would like to post gct file and a data log but i don't know how.the program is set for cloosed loop rpm 1100 and 800 .should i set them higher,it seem like this entire ve table is way too rich,i don't want to ruin my o2sensor.
 
i'm new to fast,trying to set up tune.i have good base program from vendor which was great on same combo,on know every car is different but i have tried several gct files.my problem is i have to pull so much out of my ve table to get o2 correction even close.in all the gct files i have, idle to transitional ve #'s are 30 to 55ish range .i have to pull this range down to almost single digits to be close to my target afr .i have checked all enrichment tables ,all around zero,all sensors look good,all parameters look good as far as injector size,displacement,map bar,etc...why should my ve table be so different with same combo?heres my combo ,.20over with caps,k1 rods ,champion unported aluminum heads,around 214/214 roller(may be wrong it's been a while),ported ebay headers,ported stock intake,70mm tb+doghouse,large frontmount w 3in piping,3 inch dp,test pipe,3in exhaust,83's,accufab adj reg,double pumper,ptim70mm w .82 exhousing,xfi,4inch intake,and the list goes on....

vender is more than willing to help but i want to play tonight but don't want to bother him.
1.are u supposed to tune in open or closed loop?if open there is no o2 correction to look at.
2.at idle my ve wants to be set a single digits,in all other gct files its around 30 to 40.i have adjusted throttle blades so iac is 15 to 25.all this is done warmed up around 160deg.fuel pressure set at 43 with hose off,and other pump is coming on around 10psi.

Check your voltage on your laptop. The XFI reads ign voltage v/s battery voltage. The The laptop would not show the same voltage that we had right at the pin going into the ECU. Then the Battery voltage compensation screws everything up. Starts adding fuel at like 13.8 volts. No table to correct it either. You can add it to the dashboard to see if it is adding fuel. Seems to wreck idle fueling more than anything but does affect fueling across the board. Think you have it tuned out and it will change. There are other problems we ran into that there are no fixes for yet.
 
ok battery voltage with engine off though xfi was 12v battery correction was 7,engine running xfi showed 13.8v and 1.6% battery correction,checked voltage at battery terminals,about 14.15v idling.i think that is normal reading for xfi??don't they state .2.3v loss to ecm.
 
i was also wondering about knock,i have stock sensor and harness to caspers adaptor to xfi,do i monitor knock through esc retard pid?what should i look for?i have had nothing in the datalogs for this pid.i read this is electronic spark control but i just want to make sure when i get this thing tuned im not hurting it.thanks again
 
ok battery voltage with engine off though xfi was 12v battery correction was 7,engine running xfi showed 13.8v and 1.6% battery correction,checked voltage at battery terminals,about 14.15v idling.i think that is normal reading for xfi??don't they state .2.3v loss to ecm.

Normal to add fuel at 13.8 volts? That is fueling added to the base. Thats why your idle numbers are so low. Play with it some. Every time your voltage makes even a slight change so does your fueling. Wait till the fan kicks on or you hit the brakes and then check it out. The .3 drop is much better than than the car that I had the problem with.
 
oh yea this is my baby(the money pit) any suggestions welcome!!
 

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