View Single Post
Old 01-01-2021, 04:15 AM   #8 (permalink)
serialk11r
Master EcoModder
 
Join Date: Jan 2012
Location: United States
Posts: 1,756

spyder2 - '00 Toyota MR2 Spyder
Thanks: 104
Thanked 407 Times in 312 Posts
Quote:
Originally Posted by Ecky View Post

I was pretty surprised when I found idle is generally controlled by ignition timing in modern vehicles, and not by throttle, or an idle valve, or fueling. I'm fairly certain this is in large part because those methods would respond too slowly for transient loads (electrical, A/C, letting out the clutch), but it certainly seems wasteful to give way more air and fuel than is necessary to idle the engine, and then keep RPM in place by retarding ignition timing.
That doesn't sound right to me, my Scion FR-S definitely used the throttle to control idle, timing was pretty consistent (until you step on it, then it retards a lot since the engine is knock prone).

When I was messing around with it, if my tune produced a crappier idle, the ECU would automatically run rich to compensate.

What engine did you find that uses timing to change the idle?
  Reply With Quote