WHY?? AFR Roller Coaster at steady state driving
11-30-2006, 05:09 PM
#1
WHY?? AFR Roller Coaster at steady state driving Small annoyance but it is driving me crazy.
When:
-Steady state driving
-RPM = 1000 --- 2500
-TP = 10% --- 18%
It feels like a surge when cruising along. The surge feeling mirrors the up and down AFR (see pic below)...
Any ideas or help??? All mods in SIG...
When:
-Steady state driving
-RPM = 1000 --- 2500
-TP = 10% --- 18%
It feels like a surge when cruising along. The surge feeling mirrors the up and down AFR (see pic below)...
Any ideas or help??? All mods in SIG...
Last edited by SideStep; 11-30-2006 at 05:20 PM.
11-30-2006, 05:31 PM
#3
Originally Posted by 12secSS
I take it your are in closed loop ... if so that is typical. I would suggest not to tune with the wideband in closed loop, since the NBO2 will screw with the fueling.
It was tuned while in open-loop, SD (for VE table) and then open-loop MAF calibration. Both with Wideband. Once I got it all nailed down I re-enabled closed-loop and got what you see...
11-30-2006, 06:02 PM
#4
TECH Addict
iTrader: (10)
Join Date: Jun 2004
Location: Commerce Twp, MI
Posts: 2,918
Likes: 0
Received 0 Likes
on
0 Posts
Well, that's the way closed loop works. It adds a little fuel and subtracts a little fuel around stoich. Then, it takes the averages of what it sees with the NBO2's and determines whether or not it needs to increase/decrease the LTFT's. That swing that is averaged is your STFT's.
11-30-2006, 06:49 PM
#6
Originally Posted by SSpdDmon
Well, that's the way closed loop works. It adds a little fuel and subtracts a little fuel around stoich. Then, it takes the averages of what it sees with the NBO2's and determines whether or not it needs to increase/decrease the LTFT's. That swing that is averaged is your STFT's.
Well it certainly isn't normal... My AFR swing closed loop avgs a tad lean, something like 14.5/14.6-14.8....
Look at the trim swings, they look pretty aggressive which may be why the 02s hang rich and then lean for so long. Or maybe the NBs are just lazy in that RPM range... which 02s are you running?
11-30-2006, 07:34 PM
#7
Originally Posted by Frost
Well it certainly isn't normal... My AFR swing closed loop avgs a tad lean, something like 14.5/14.6-14.8....
Look at the trim swings, they look pretty aggressive which may be why the 02s hang rich and then lean for so long. Or maybe the NBs are just lazy in that RPM range... which 02s are you running?
Look at the trim swings, they look pretty aggressive which may be why the 02s hang rich and then lean for so long. Or maybe the NBs are just lazy in that RPM range... which 02s are you running?
Like I said above you can feel the rich/lean swings as a surge/stumble...
I have the wideband on the passenger side before the X-Pipe..
Trending Topics
11-30-2006, 10:56 PM
#8
Moderator
iTrader: (11)
Join Date: Mar 2002
Location: East Central Florida
Posts: 12,605
Likes: 0
Received 6 Likes
on
6 Posts
Reducing the proportional fuel amount, for the
airflow mode cells you are in at light cruise, ought
to settle this down.
Something too about a delay value that wants to be
tweaked up when you move the NBO2s further back in
the pipe. Forget the name. But think that may also
contribute to instability at low gas flows, taking longer
for the fueling change to produce the crossing sought
and maybe overtravelling more as a result.
airflow mode cells you are in at light cruise, ought
to settle this down.
Something too about a delay value that wants to be
tweaked up when you move the NBO2s further back in
the pipe. Forget the name. But think that may also
contribute to instability at low gas flows, taking longer
for the fueling change to produce the crossing sought
and maybe overtravelling more as a result.
12-01-2006, 07:27 AM
#9
Originally Posted by jimmyblue
Reducing the proportional fuel amount, for the
airflow mode cells you are in at light cruise, ought
to settle this down.
Something too about a delay value that wants to be
tweaked up when you move the NBO2s further back in
the pipe. Forget the name. But think that may also
contribute to instability at low gas flows, taking longer
for the fueling change to produce the crossing sought
and maybe overtravelling more as a result.
airflow mode cells you are in at light cruise, ought
to settle this down.
Something too about a delay value that wants to be
tweaked up when you move the NBO2s further back in
the pipe. Forget the name. But think that may also
contribute to instability at low gas flows, taking longer
for the fueling change to produce the crossing sought
and maybe overtravelling more as a result.
