sc300 rpm question
11-14-07, 10:15 AM
#1
sc300 rpm question
i tried searching but couldnt find a good answer.
when my car is warmed up and in drive, when i stop my rpm sit at about 600-650 which seems normal right?
when i shift the car in nuetral (still at a stop) my rpm gauge does not move at all. is this the lexus ecu being smart or is there something wrong cause none of my other automatic cars stay the same rpm. all of them go up to 800-900.
if i then tap the accelerator in neutral, it will drop down to 800, then it will slowly lower itself back to about 600-650.
is this normal? should i be concerned? also what rpm should it be with a/c on?
i am going to seafoam it but i just wanted to see if this is ecu being "smart" or is this a mechanical problem or not a problem at all. thanks
when my car is warmed up and in drive, when i stop my rpm sit at about 600-650 which seems normal right?
when i shift the car in nuetral (still at a stop) my rpm gauge does not move at all. is this the lexus ecu being smart or is there something wrong cause none of my other automatic cars stay the same rpm. all of them go up to 800-900.
if i then tap the accelerator in neutral, it will drop down to 800, then it will slowly lower itself back to about 600-650.
is this normal? should i be concerned? also what rpm should it be with a/c on?
i am going to seafoam it but i just wanted to see if this is ecu being "smart" or is this a mechanical problem or not a problem at all. thanks
11-14-07, 01:11 PM
#2
Lead Lap
Join Date: Jul 2006
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If you ask me that is good design. To me, the reason RPM is higher in neutral is because the clutch is disengaged from the engine. In drive your engine and transmission is under load and therefore RPM may drop. So to me, what you have is balanced.
11-14-07, 01:20 PM
#3
yeah, its nice to not get the thud, i just want to know if its normal.
i do have a crazy intake whistle too and i think its related.. check it out.
http://www.clubna-t.com/forums/showt...hp?page=2&t=10
apparently at 4500 rpm's (WOT only) the iacv valve opens slightly to change the effective intake length and volume to help torque,
it once again changes this at 6100 rpm's according to this post.
this is exactly when my car starts to whistle and it does change at 6100 rpm to a different whistle. i assume they didnt design it to whistle so something must be restricted. i think the iacv valve needs a good cleaning so it can work 100% like its supossed to and not open just enough to make a whistle and affect my idle randomly.
im assuming that the ecu is learning to compensate for the iacv valve not working and effectively lowering the idle that way.
no one can confirm that there rpm changes from drive to neutral?
i do have a crazy intake whistle too and i think its related.. check it out.
http://www.clubna-t.com/forums/showt...hp?page=2&t=10
apparently at 4500 rpm's (WOT only) the iacv valve opens slightly to change the effective intake length and volume to help torque,
it once again changes this at 6100 rpm's according to this post.
this is exactly when my car starts to whistle and it does change at 6100 rpm to a different whistle. i assume they didnt design it to whistle so something must be restricted. i think the iacv valve needs a good cleaning so it can work 100% like its supossed to and not open just enough to make a whistle and affect my idle randomly.
im assuming that the ecu is learning to compensate for the iacv valve not working and effectively lowering the idle that way.
no one can confirm that there rpm changes from drive to neutral?
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