bad6as

iTrader: (17)

well im trying to get rid of some bucking from 1200-2200 rpms and i was told to look at fuel first. i logged ltft on bank one and two. and hit the cells where it normaly does it and thats what i got.

most the numbers are in the negitive so i subtracted thoes numbers from my ve numbers in the same cells and smoothed out the surounding cells but when i did a log again the numbers where more off.

how should i change the ve values and how much

BLK02WS6

iTrader: (2)

What were the trims? Did you use the bi-directionals and clear the fuel trims out before logging again? It takes some driving to relearn them. Did pulling the fuel out help the bucking in that area?

I can't look at your files here... no laptop.

bad6as

iTrader: (17)

when you reflash the pcm dosent it clear every thing out?
once i changed some of the ve table the numbers went alot higher.
on the map the numbers where in the -.75 threw -3 range then once i changed it it went to -5 to -8

BLK02WS6

iTrader: (2)

If that's the case, they were pretty good before (you want them close to zero, but negative). Are you sure you added negative numbers to the VE table? Anyway, I would put the VE back to what it was.

The next thing I would look at for the bucking would be the throttle cracker table - try adding a little bit of air (like .4 grams to start) in the rpm/mph that it is bucking and see what it does... fine tuning out little spots takes some time and patience...

bad6as

iTrader: (17)

so i dont wangt them in the negative range? how do i clear the fuel trims if i didnt all ready?
say the one cell was -2.4 and the ve table thta cell was 43.2200 i subtraccted 2 and changed that cell to 41.200 just an example. is that the right way to do it?

as of now i went back to the ve table that it had in it the last time i left fbc

BLK02WS6

iTrader: (2)

Yes, you want them to be small negatives, within a few percent of zero. If that is the way you did it, then you leaned out the VE in that cell... To clear the learned fuel trims, go under the bidirectional controls and find the button to clear them - when you click it, you will see them zero out...

Your VE should have been in good shape, and based on the fuel trims you were seeing, I would leave it alone.

Work on the throttle cracker and see if that doesn't smooth it out.

bad6as

iTrader: (17)

ok and what mph should the throttle cracker turn on and off?
and its table b4309 you talking about changing

Goldfinger911

iTrader: (24)

If it does it when it is fully warm still, and your VE is close, BLK02WS6 is right... the problem is being contributed to by your T-Cracker and T-Follower tables. At that RPM you are probably bouncing between 0% and 4% throttle, right? When it is bucking... can you tell if it feels like the bucking is a surging or a slowing? (With my cam, it took me a week to get those two tables right... now I can put around at 1200rpm in 2nd gear all day.) Check out my tune if you want (sig).

You should share yor specs of your setup too. Makes prescribing a solution easier.

Are you running an aftermarket cam? If so, 40 deg of timing while putting around at 3-5% throttle at 37-47kpa might be too much. However don tmess with timing now... get those throttleT/F tables right first.

bad6as

iTrader: (17)

232/234 110+3 cam xer lobes. 3.90s longtubes, ls6 im, ported tb, 85mm maf, 85mm lid ftra.

when it bucks it dosent feal like its trying to slow down

dlove

iTrader: (23)

get a wideband and autoVE it

BLK02WS6

iTrader: (2)

That's been done...

BLK02WS6

iTrader: (2)

I think what he is getting at is does it buck with your foot on the gas, or coasting with it off... Either way, the cracker and follower tables are the key. Cracker effects more with foot on the gas coasting and the follower effects more when you come off the throttle. There is a very fine line on these and it takes time and small changes to get them exactly on. Look at his tune like he suggested and check out his cracker/follower and decay rate tables. Welcome to the wonderful world of fine tuning LOL...

bad6as

iTrader: (17)

does it both. not all the time just every so often

BLK02WS6

iTrader: (2)

Try adding a little air in the rpm/mph area like I said - only change one table at a time. If it hangs too long, increase the decay a little and it will come down quicker as you slow down and stop. It takes trial and error, but only make small changes and only one table at a time so you can see what effect it has.

bad6as

iTrader: (17)

ok so ill add some air to the 1600 rpm row from 26-103 km/h. it was at 1.50 so i went to the next row and that was 2.20 and used that. (this it to get rid of the bucking)

so if im costing in neutral to a stop and the rpms hang to high or take too long to idle once im stopped i make the numbers in the throttle follower decay rate in gear table higher. but in that table there is 4 rows 1st 2nd 3rd and 4th do i raise all them or just one or the other. (this is if the rpms hang to much)

BLK02WS6

iTrader: (2)

No, if you are adding air to the throttle cracker table for the bucking, and it hangs when you are coming to a stop, increase the throttle cracker decay rate table to make it drop faster.

If RPM drops too much when you pull your foot off of the throttle, add air to the throttle follower table to stop the RPM dipping. If it hangs after adding air to the follower table, increase the decay rate tables for the throttle follower.

There is a fine line on when each of these tables effects airflow - but if you only change one of them at a time, you will get a feel for what each does.

bad6as

iTrader: (17)

thanks ill do some logs when i get home

bad6as

iTrader: (17)

ok what tabe are you talking about exactly for each follower tables.
i lowered the throttle cracker and seams to have gotten better.
but rpms still hang a bit to high and long when im costing to a stop.
when i let off the throttle when still in gear i get some bucking. what table do i go to for that

bad6as

iTrader: (17)

ok so bucking is about gone, but i have two other questons.
when its in neutral or my foot is on the clutch and i rev it when the idle comes back down some times it will fall to say 600 then fix its self, also when im pulling away from a light and just baby in to it and hit the clutch and brake it will do it to. what do i need to look at for that

2nd queston is when its cold when i start it now the idle jumps around some, then after i minute or two you can hear it out of no where idle perfect. what should i do about that too.

Doc

iTrader: (9)

Sorry for the late response but, what method of airflow measurement are you using?

SD,
MAF,
Blend
?
Just by going by your thread and sig I was confused.