Help me with fuel trims
12-07-2006, 11:37 AM
#1
TECH Apprentice
Thread Starter
iTrader: (1)
Join Date: Apr 2006
Posts: 301
Likes: 0
Received 0 Likes
on
0 Posts
Help me with fuel trims Can someone give me a hand with adjusting my fuel trims. They are all over the place but usually are in the area of 4.5 to 6.5 (ltft bank 1 and bank 2). I have not messed with anything motor wise (just did some torque mgt.). I am in no rush to get this done as in one sitting so not looking to dis-able 200 different things, what fuel table can I adjust a little to add some fuel? (PE and VE?)I dont mind adjusting it and then driving on it for a week or to to let them settle. What % would you guys think I should enter?
I dont have a wide band 02 yet. Set up is 99Z magnaflow cat back, p&p t/b, egr cut, lid, 3.73's.
Thanks for any help.
I dont have a wide band 02 yet. Set up is 99Z magnaflow cat back, p&p t/b, egr cut, lid, 3.73's.
Thanks for any help.
12-07-2006, 11:41 AM
#2
https://ls1tech.com/forums/pcm-diagnostics-tuning/287094-read-me-first-tuning-docs-ve-maf-ses-lights-faqs-more-01-31-07-a.html this is the best place to start...members of this forum took alot of time to make these tuning 101 guides that explain exactly what you need to do, please don't let their time spent go to waste.
12-07-2006, 12:10 PM
#3
TECH Addict
iTrader: (10)
Join Date: Jun 2004
Location: Commerce Twp, MI
Posts: 2,918
Likes: 0
Received 0 Likes
on
0 Posts
I'd set PE to something in the range of 12.2:1~12.5:1 AFR across the board (EQ=1.20~1.17). 12.5:1 (1.17) should be safe, but richen it up a little if you see some KR consistently when you go WOT. If that doesn't change anything, then chances are the KR you're seeing isn't fuel related. I don't think you'll see any anyways with this setup assuming you didn't change the stock timing tables (really don't need to on light bolt-on cars).
Then, I'd increase the MAF table 1% over stock from 2500-2875Hz, 2% from 3000-3375Hz, 3% from 3500-3875Hz, 4% from 4000-4375Hz, and 5% from 4500Hz on up. That should get you close until you can verify it with a WBO2 and dial it in.
BTW - I didn't pull those numbers out of my ***. They are based on how I tuned my '02 Z (mods in sig below). They should have you a little on the rich/safe side, but not as rich as it comes from the factory. Consider it a mail-order AFR tune.
Then, I'd increase the MAF table 1% over stock from 2500-2875Hz, 2% from 3000-3375Hz, 3% from 3500-3875Hz, 4% from 4000-4375Hz, and 5% from 4500Hz on up. That should get you close until you can verify it with a WBO2 and dial it in.
BTW - I didn't pull those numbers out of my ***. They are based on how I tuned my '02 Z (mods in sig below). They should have you a little on the rich/safe side, but not as rich as it comes from the factory. Consider it a mail-order AFR tune.
Last edited by SSpdDmon; 12-07-2006 at 12:17 PM.
12-07-2006, 12:17 PM
#4
TECH Apprentice
Thread Starter
iTrader: (1)
Join Date: Apr 2006
Posts: 301
Likes: 0
Received 0 Likes
on
0 Posts
Im not making their time go wasted. I have read them (or at least the links that still work), and was wondering what %'s people are useing to change the ltft. I would like to do this without all of the disableing stuff. I understand it will take longer to get it right, most of those post are for those with wb 02 and or require shutting 1/2 the trims down and unplugging the mas.
I give everyone a
for their write ups. They did a great job and I have learned a lot from them.
I give everyone a
for their write ups. They did a great job and I have learned a lot from them.
12-07-2006, 01:56 PM
#6
TECH Fanatic
iTrader: (12)
Join Date: Jan 2004
Location: Houston, TX
Posts: 1,869
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by marthastewart
Im not making their time go wasted. I have read them (or at least the links that still work), and was wondering what %'s people are useing to change the ltft. I would like to do this without all of the disableing stuff. I understand it will take longer to get it right, most of those post are for those with wb 02 and or require shutting 1/2 the trims down and unplugging the mas.
I give everyone a for their write ups. They did a great job and I have learned a lot from them.
I give everyone a
for their write ups. They did a great job and I have learned a lot from them.IE: If you have a -6 trim, a 1 to 1 fueling adjustment in terms of a percetage would be -6%. We might think, ok, PCM is taking out 6% fuel, decrease the value by 6% (or multiply by .94). It's not quite a 1 to 1 ratio of adjustment (trimming compared to fueling adjustment), so instead let's be conservative and decrease the value by 3% (multiply by .97). This should drop you very close to 0 (-1 or -2 probably), but don't fret if you never get to 0, it's not a perfect world
12-08-2006, 01:38 AM
#7
TECH Apprentice
Thread Starter
iTrader: (1)
Join Date: Apr 2006
Posts: 301
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by SSpdDmon
I wasn't suggesting you shut anything down. Just change 2 tables and see how the trims react over the next 100 miles. I'll bet ya I'm close.
Yeah I know, you posted that prior to my post (did not even see yours). You put up exactly what I was looking for.
Txhorns you did as well.
Thanks a lot to both of you guys!
Trending Topics
12-08-2006, 08:14 AM
#8
TECH Addict
iTrader: (10)
Join Date: Jun 2004
Location: Commerce Twp, MI
Posts: 2,918
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by txhorns281
A safe place to start with would be half of whatever trimming you're noticing. So locate which areas of the MAF range (or VE table for SD fueling), and adjust by 1/2 just so you can see the effect. It will be close, and from there you should be able to get a feel for what magnitude of adjustment makes what sort of impact.
IE: If you have a -6 trim, a 1 to 1 fueling adjustment in terms of a percetage would be -6%. We might think, ok, PCM is taking out 6% fuel, decrease the value by 6% (or multiply by .94). It's not quite a 1 to 1 ratio of adjustment (trimming compared to fueling adjustment), so instead let's be conservative and decrease the value by 3% (multiply by .97). This should drop you very close to 0 (-1 or -2 probably), but don't fret if you never get to 0, it's not a perfect world
IE: If you have a -6 trim, a 1 to 1 fueling adjustment in terms of a percetage would be -6%. We might think, ok, PCM is taking out 6% fuel, decrease the value by 6% (or multiply by .94). It's not quite a 1 to 1 ratio of adjustment (trimming compared to fueling adjustment), so instead let's be conservative and decrease the value by 3% (multiply by .97). This should drop you very close to 0 (-1 or -2 probably), but don't fret if you never get to 0, it's not a perfect world
12-08-2006, 08:41 AM
#9
FormerVendor
iTrader: (9)
Join Date: May 2003
Location: Jacksonville, Fl
Posts: 1,573
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by txhorns281
This should drop you very close to 0 (-1 or -2 probably), but don't fret if you never get to 0, it's not a perfect world
12-08-2006, 09:00 AM
#10
TECH Fanatic
iTrader: (12)
Join Date: Jan 2004
Location: Houston, TX
Posts: 1,869
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by SSpdDmon
I think it is pretty close to a 1-to-1 ratio with the MAF. Day to day weather changes will affect the tune. But way back before I ever got into the whole EFI Live thing, I had a Predator. I would see fuel trims as high as +5~+6. Fast forward to me hooking up the wideband and EFI Live....my MAF table has a pretty flat 6% increase over stock from about 4500Hz on up. I'm not saying cutting your correction in half is a bad idea. It's actually a great way to avoid overshooting. But the first time around, 50% of the actual correction is going to take a few more rinse & repeats than applying 100% of the correction.
And in addition to earlier advice, don't get too hellbent on getting your trimming to 0. If all of our trims could stay at zero then we'd be living in a perfect experiment. People say to stay slightly rich of zero trimming (-4 to 0) simply b/c it's close enough as far as the theory goes and running slightly rich helps avoid pulling positive trims into WOT fueling (which can result in richer than expected A/F ratios at full throttle).
12-08-2006, 09:02 AM
#11
TECH Fanatic
iTrader: (12)
Join Date: Jan 2004
Location: Houston, TX
Posts: 1,869
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by Doc
Do you suffer from Obsessive Fuel Trim Examination Notation? Many tuners suffer needlessly from OFTEN. There is a cure, it's called Open Loop Speed Density or OLSD. 9 out of 10 tuners using OLSD report relief from OFTEN. Side effects from using OLSD may include but may not be limited to increased throttle response, improved fuel economy and dry itchy mouth.
Three cheers for getting 
12-09-2006, 02:01 AM
#15
TECH Apprentice
Thread Starter
iTrader: (1)
Join Date: Apr 2006
Posts: 301
Likes: 0
Received 0 Likes
on
0 Posts
Txhorns and SSpdDmon thanks a lot for the help. You guys got me headed in the direction I was looking for. I was begining to go nuts reading all the post on this stuff and everyone has a slightly different way to do everything which makes it twice as confusing. You guys gave the exact stuff I was lookind for, my trims are almost a perfect 0, and the WOT has a lot more pull without any KR.
Thanks again
Thanks again