Red99TA

iTrader: (11)

I'm running in SD and am in the process of tuning my VE table. Whether hot or cold whatever gear I'm in I get a bad hesitation from 1100 rpms up to about 1500 rpms. I don't notice it at light throttle say 10% TPS but up around 25% and above and it hesitates bad and I'll see some knock every now and then (around 2 - 3 degrees max). I know it's not going into PE based on my TPS settings. I've tried playing with VE columns 800-1600 (adding and subtracting fuel) and I've tried adding/subtracting spark and neither made any difference. I also noticed that when it's doing this the O2's go to 25 - 50 mV and stay there (flatlined). I'm not sure why the O2's do this or if this has anything to do w/ the hesitation. Please help.
TIA,
Geoff

technical

Not knowing what a WB reading looked like, I'd have to guess you should pull a degree or two worth of timing and add more fuel. I know you have been adding, but I suspect you should add at least 1.5x the max amount you have previously tried. The situation "sounds" like a lean condition. If you had mentioned a bucking I would have went the other way.

Red99TA

iTrader: (11)

I'll give it a shot. The most I was changing before was + or - 20%.

Red99TA

iTrader: (11)

Just added 30% fuel in 1200-1600 columns with no effect. I can make the car do this in 4th or 5th gear starting around 1200 rpms and then opening the throttle about 50%. I don't understand why the O2's go to almost 0 mV and stay there while the hesitation is happening. It seems like during normal driving the O2's oscillate no problem and at WOT they shoot up to where they should be (around 920 mv). Any ideas?

technical

Where do you have PE set to enable? I can't remember off the top of my head where default is....

Red99TA

iTrader: (11)

Enabled above a MAP of 15 with at least 64% throttle and this crap is happening less than 64%

technical

Did this start right after the TB install?

Red99TA

iTrader: (11)

No, I just downloaded some new tables from another user who got me up and running in SD...my previous mail-order tune was all jacked up to the point where it hesitated like crazy in open loop while in SD in every gear at any rpm. Now it runs fine except for this hesitation at low rpms.

technical

Post up some logs and the VE table if possible. I was starting to think you had an air leak that was causing the hesitation while transitioning into load, but it may just be the calibrations. Double check for air leaks just to make sure we're not chasing a ghost.

Patrick G

iTrader: (14)

Often, bucking and surging has to do with the IAC fighting against you. After you get your timing and VE tables perfect, then get your base running airflow nailed so your Desired Airflow and Dynamic Airflow match at all temps (AC on and off). To do this, you'll need to mess with your IAC Effective Area table.