revs seem funny?

**mammoth713** · 10-21-2009, 05:11 PM

today i noticed (of course right before storage tomorrow) that my car's RPMs seem to float higher once i put in the clutch and go to shift into the next gear... and my foots not on the gas at all... and it just floats a little higher... just enough for me to notice

actually, i first noticed it when i put on the catback and it seemed to just breath better...

is this normal or is it a throttle position sensor or something?

**toi tyme** · 10-21-2009, 06:17 PM

my car sits at a higher RPM when in neutral than in park or drive.... is this what you mean, i have an auto.

**Mr. Luos** · 10-21-2009, 06:32 PM

How many miles ago did you install the catback?

How much higher does it 'float?'
If you are coming to a stop and have it in neutral, does the car normally sit at regular idle? Or does it hang around 1300-1500 RPM?

**pajeff02** · 10-21-2009, 06:38 PM

The instructions with our catback system directed that the battery be disconnected in order to force the PCM to "re-learn" with the lower restriction exhaust. This may be your issue -- but it could also easily be a vacuum leak or sensor problem as well.

**casperss** · 10-21-2009, 07:49 PM

Originally Posted by Mr. Luos

How many miles ago did you install the catback?

How much higher does it 'float?'
If you are coming to a stop and have it in neutral, does the car normally sit at regular idle? Or does it hang around 1300-1500 RPM?

Hey thats what mine does. I thought it was normal, or am I wrong?

**mammoth713** · 10-21-2009, 07:54 PM

installed the catback around 1k miles ago? maybe a little over 1k?

but yeah i deffinately noticed it started "floating" lets say it goes up around 300 rpms tops once i put the clutch in to shift to the next gear... my friend and i noticed it right when we test drove it after the install but figured it was cuz the engine was "breathing" better... but i am not sure..? its not like it happens on every shift but it is prevalent enough so i noticed it.

i dont remember the directions saying anything about that but you may be right... i never fully read directions hahaha. so by disconnecting the battery the PCM recalibrates the intake/exhaust senors etc...?

**Mr. Luos** · 10-21-2009, 07:59 PM

Originally Posted by mammoth713

i dont remember the directions saying anything about that but you may be right... i never fully read directions hahaha. so by disconnecting the battery the PCM recalibrates the intake/exhaust senors etc...?

No.

The PCM will relearn without disconnecting it.
It could just be a change in the air. Or a dirty MAF.

**pajeff02** · 10-22-2009, 03:40 AM

Originally Posted by Mr. Luos

No.

The PCM will relearn without disconnecting it.
It could just be a change in the air. Or a dirty MAF.

Agreed. The PCM will always be changing things based on sensor feedback. Disconnecting the battery forces it to do so on initial start up. Usually, the engine rpm will start out a little low and it will hunt for idle. Took our car under 2 minutes to get back to where it was supposed to be.

**mammoth713** · 10-22-2009, 04:26 PM

hmm well the car is in storage

begining today... now i'm driving my 93 lesabre and hating this. ahhaah

**Cutlass** · 10-23-2009, 05:32 PM

Reminds me a little of this thread...
http://www.ls1.com/forums/showthread...ht=idle+moving
BTW my car just starting doing this too. Wonder if its the cold weather? I'm gonna hook up the scan tool and check the IAC counts, TP sensor, and Fuel trims to see if I can come up with something.