Hi Sludgy -¨I remember old automatics where the rpms would drop when you went from N to D.¨
When an auto is placed into gear there is more load on the engine than at idle , so it is logical that a reduction of rpm is noticed., especialy at idle when the engine is making very little power.
Older auto cars would just have a slightly lifted idle speed so when a gear is selected the engine speed drops down to a normal idle.
On many autos their ignition settings and camshaft specs may be different compared to a manual to allow a slower idle speed , ,and a power band more suitable for the auto trans. application.
In almost all auto EFI cars they use a thing called ¨idle up solenoid¨
When D is selected the solenoid will activate increasing the speed.
Even many manual trans cars have this fitted to lift the idle when the air conditioner kicks in.
A ¨Drive by wires¨ exact application would mean NO physical conection between the operator and the throttle system.
I havent seen any cars (ime sure they exist) that are done this way .. almost all still use a throttle cable to a butterfly on the intake side of the engine somewhere.
PS . on some cars they have an idle up soilenoid which may work mechanically on the throttle linkages to increase idle speed , but some do it by bypassing more air past the throttle butterfly , this is usually called ¨Idle air control¨= IAC.
Diferent way , but same overall result.
you will get better mpg without a muffler. leading reason:
even though you say you can stand the sound, you really wont, and in turn you will go lighter on the throttle and end up saving fuel that way.
my muffler rusted off. i got better fuel economy because i never wanted to floor it. then the rest of it rusted off right behind the header the next week. fortunately i already had my new exhaust in the mail, but i did drive to work open header for one day. that was so loud that i didnt baby it anymore, i just floored it everywhere cus it was just so rediculous.
i have to admit, open header pulled like a freight train. i had fun in that one day.
don't waste your time or time will waste you