ok...new motor/bolt ons/stall...hp tuners and need HELP PLEASE!
01-03-2006, 11:00 PM
#1
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ok...new motor/bolt ons/stall...hp tuners and need HELP PLEASE! ok, I have searched and searched and tried things etc etc...Heres is the mod list on the car.
-98 TA
-new 03 LS6 motor and heads
-FM14 cam/spring package
-yank 4200 stall
-FAST 90mm/90mm combo
We have been messing with HP Tuners on the car for 2 days now. Heres whats been going on.
-You can start the car, and we got it to idle what seems to be pretty good, it looks like it fluctuates from about 800-1000 at times.
-Once you give the car any kind of gas, it either holds the rpms up or it surges and then tries to go back to idle again
-When you are driving on the highway. its cruise control and sticks there until you come to a stop and seems to kick down to a normail idle rpm but then it starts surging from like 500-800.
--the car was throwing misfires like crazy, i guess thats normal with a big cam and convertor. We worked the misfires out with some tuning and those seem to be ok and not throwing a code anymore.
--The 90mm TB isnt the best setup i have seen before. Ive got a piggyback return spring on it now to allow it to try to close all the way and it seems like that still doesnt work sometimes. Ive got to pull it back with my hand to get it to idle back down (its actually pretty hard to pull back with my hand) We've got a hole in the blade and tried to tune around that.
--Seriously, I hate that I put so much work and money in the car and i cant get it right. Any info is appreciated. Like what numbers I should have in, etc..
I have been trying what everyone has done in previous searches and everyone has a little bit different set-up and everyone says something different, I thought id post my mod list and see what you big dogs had to say about it...Thanks ALOT in advance! Let me know what i need to do or what I can do to help you guys help me.
-98 TA
-new 03 LS6 motor and heads
-FM14 cam/spring package
-yank 4200 stall
-FAST 90mm/90mm combo
We have been messing with HP Tuners on the car for 2 days now. Heres whats been going on.
-You can start the car, and we got it to idle what seems to be pretty good, it looks like it fluctuates from about 800-1000 at times.
-Once you give the car any kind of gas, it either holds the rpms up or it surges and then tries to go back to idle again
-When you are driving on the highway. its cruise control and sticks there until you come to a stop and seems to kick down to a normail idle rpm but then it starts surging from like 500-800.
--the car was throwing misfires like crazy, i guess thats normal with a big cam and convertor. We worked the misfires out with some tuning and those seem to be ok and not throwing a code anymore.
--The 90mm TB isnt the best setup i have seen before. Ive got a piggyback return spring on it now to allow it to try to close all the way and it seems like that still doesnt work sometimes. Ive got to pull it back with my hand to get it to idle back down (its actually pretty hard to pull back with my hand) We've got a hole in the blade and tried to tune around that.
--Seriously, I hate that I put so much work and money in the car and i cant get it right. Any info is appreciated. Like what numbers I should have in, etc..
I have been trying what everyone has done in previous searches and everyone has a little bit different set-up and everyone says something different, I thought id post my mod list and see what you big dogs had to say about it...Thanks ALOT in advance! Let me know what i need to do or what I can do to help you guys help me.
01-04-2006, 08:46 AM
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The lightweight converter will destabilize idle all on
its own, in my experience. For me it took a few things
like upping the idle RPM (only to 700, on a no-motor-
mods setup), raising the idle airflow table values to
about 90% of observed steady airflow readings (as a
"backstop" for the RPM control loop), adding idle spark.
On a cam car you also have compounding idle effects
from mixture error - VE table, and the open loop fuel
air table when cold / open loop, driven by the lower
vacuum level (higher MAP) into high enrichment. This
makes the motor "soggy" (idle air loop lag -> oscillation).
This (OLFA vs MAP) has its own positive feedback effect
because overenrichment further raises the MAP needed
to hold idle, in turn indexing to even higher enrichment,
etc.
O2 sensors that have slow response are another idle lag
/ destabilizer. The short term mixture control bouncing,
erratically, constantly perturbs the idle RPM/air control
loop off center.
You might want to turn off closed loop, try and get the
hot idle mixture clean (by wideband or narrowbands, close
(enough) to 0.5V, and see if the idle can then be put
stable. If so then suspect the O2s and fuel loop as the
destabilizer. Too many cooks, etc.; shoot one and taste
the soup again.
its own, in my experience. For me it took a few things
like upping the idle RPM (only to 700, on a no-motor-
mods setup), raising the idle airflow table values to
about 90% of observed steady airflow readings (as a
"backstop" for the RPM control loop), adding idle spark.
On a cam car you also have compounding idle effects
from mixture error - VE table, and the open loop fuel
air table when cold / open loop, driven by the lower
vacuum level (higher MAP) into high enrichment. This
makes the motor "soggy" (idle air loop lag -> oscillation).
This (OLFA vs MAP) has its own positive feedback effect
because overenrichment further raises the MAP needed
to hold idle, in turn indexing to even higher enrichment,
etc.
O2 sensors that have slow response are another idle lag
/ destabilizer. The short term mixture control bouncing,
erratically, constantly perturbs the idle RPM/air control
loop off center.
You might want to turn off closed loop, try and get the
hot idle mixture clean (by wideband or narrowbands, close
(enough) to 0.5V, and see if the idle can then be put
stable. If so then suspect the O2s and fuel loop as the
destabilizer. Too many cooks, etc.; shoot one and taste
the soup again.
