Help with off idle hanging or cruise???
09-12-2006, 08:31 AM
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Help with off idle hanging or cruise??? Help with off idle hanging or cruise??? Using hp tuner or ls1 edit, I have an issue with as soon as i pull away from an intersection the rpm goes up and the car wants to cruise at 1500rpm and then when i come to a stop the car wants to keep going for @3sec then it will drop down to idle at 875. Can someone please help me with this as start upcold/hot is great idle is great and drivability is great...just this anoying self cruise and hanging. the car is c5 425ci with 242/248 on a 114+4 CL LS-2 90mm TB/fast intake. 1/8 hole in blade.
MAX
MAX
09-12-2006, 09:25 AM
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You probably have excess closed throttle airflow,
perhaps a vacuum leak or an overdrilled TB blade,
and the additional throttle cracker air is too much
for the conditions. The slow decay indicates you
are dealing with it by the idle trimming loop. If you
can be sure there are no external leaks then I think
I'd start with modifying the IAC area vs position
table and add the excess throttle blade hole area
to all of the cells as an offset. That would make the
predicted air more in line with actual. Then shave on
the desired airflow until the amount you see drawn
to hit idle RPM, and the desired value shown, are
pretty close. After that the cruise may be gone; if
not then start reducing the throttle cracker airflow
value, all it's for is a soft landing (but some tables
have potholes on the runway).
perhaps a vacuum leak or an overdrilled TB blade,
and the additional throttle cracker air is too much
for the conditions. The slow decay indicates you
are dealing with it by the idle trimming loop. If you
can be sure there are no external leaks then I think
I'd start with modifying the IAC area vs position
table and add the excess throttle blade hole area
to all of the cells as an offset. That would make the
predicted air more in line with actual. Then shave on
the desired airflow until the amount you see drawn
to hit idle RPM, and the desired value shown, are
pretty close. After that the cruise may be gone; if
not then start reducing the throttle cracker airflow
value, all it's for is a soft landing (but some tables
have potholes on the runway).
