HELP...RPM's "sticking"...IAC valve???
05-30-2005, 05:28 PM
#1
HELP...RPM's "sticking"...IAC valve??? Two days ago, my car began to act a little screwey. As I would come to a stop sign or traffic light, and put the car in neutral, the idle would stick at about 1200-1300 rpm. Then, it would gradually decrease to about an 800 rpm idle. I am guessing it is the IAC valve, but I wanted to gain some insight on what other people thought it was before I started cleaning/replacing parts. Any ideas???
Thanks
Andy
Thanks
Andy
05-31-2005, 08:17 AM
#3
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I suspect there's some change to "bypass" air leakage
that has upset your idle trimming. Vacuum leak, like.
PCV valve stuck open, or hose off, crankcase seal not
tight (even oil fill cap or dipstick not seated could bump
the airflow a bit, via the PCV). This isn't big, but M6
don't have that much accessory drag.
Though you might also want to check that the TB
blade seats hard against its stop-screw and the cables
are not over-snug (though this is not the way of the
world, naturally).
There is a built-in "throttle follower" function which makes
the IAC bleed excess air when rolling, so it can keep some
authority when the throttle closes, over airflow to idle.
But this should be less of a rise than that, and crisper
in settling down. Still, things about the tune that make
a little air go a longer way, could also elevate the effect.
But like I said, a long (seconds) timescale of settling is
more like the idle control loop being offset from what it
had learned, and having to get back by the short term
trims.
that has upset your idle trimming. Vacuum leak, like.
PCV valve stuck open, or hose off, crankcase seal not
tight (even oil fill cap or dipstick not seated could bump
the airflow a bit, via the PCV). This isn't big, but M6
don't have that much accessory drag.
Though you might also want to check that the TB
blade seats hard against its stop-screw and the cables
are not over-snug (though this is not the way of the
world, naturally).
There is a built-in "throttle follower" function which makes
the IAC bleed excess air when rolling, so it can keep some
authority when the throttle closes, over airflow to idle.
But this should be less of a rise than that, and crisper
in settling down. Still, things about the tune that make
a little air go a longer way, could also elevate the effect.
But like I said, a long (seconds) timescale of settling is
more like the idle control loop being offset from what it
had learned, and having to get back by the short term
trims.
05-31-2005, 06:46 PM
#5
Just talked to my mechanic. He says it's within the LS1 program. The rpm's are sticking due to the intake and cam. He forgets what the actual name of it is called but he said it is completely normal considering the weather is getting warmer out. It's not a big deal, but I certainly did notice the "sticking" RPM's. Thanks for the reply.
Signing off
Andy
Signing off
Andy
