open vs closed mode.
Thread Starter
Melting Slicks
Joined: Oct 2000
Posts: 3,010
Likes: 1
From: Sweden/Stockholm
open vs closed mode.
When does the car goes in open vs closed mode?
And what could be wrong if the car runs great when you just started it after a night in the garage, but when it gets hot it runs much worse, power loss? False knocks? Bad MAP censor?
Regards
And what could be wrong if the car runs great when you just started it after a night in the garage, but when it gets hot it runs much worse, power loss? False knocks? Bad MAP censor?
Regards
Team Owner
Joined: Sep 2001
Posts: 62,067
Likes: 1,723
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Re: open vs closed mode. (devilfish)
the car goes into closed loop as soon as it gets up to temperature (like 160), it starts in open loop
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: open vs closed mode. (devilfish)
Upon start up ECM will go closed loop when the following all have occured:
1) a preset amount of time has elapsed
2) coolant temp reaches prescribed level
3) the O2 sensor is responding properly
It will then go into open loop (reading but ignoring O2 sensor data) when it senses the WOT condition.
When you first start up the engine is cold and you have a rich condition. Mine also has most power under this condition.
To reduce knock by lower engine temp, proper octane fuel, correct ignition timing.
I believe that a failed MAP, like a failed MAF, should throw a code. Though when my MAF failed it didn't throw a code the engine just wouldn't run.
1) a preset amount of time has elapsed
2) coolant temp reaches prescribed level
3) the O2 sensor is responding properly
It will then go into open loop (reading but ignoring O2 sensor data) when it senses the WOT condition.
When you first start up the engine is cold and you have a rich condition. Mine also has most power under this condition.
To reduce knock by lower engine temp, proper octane fuel, correct ignition timing.
I believe that a failed MAP, like a failed MAF, should throw a code. Though when my MAF failed it didn't throw a code the engine just wouldn't run.
Thread Starter
Melting Slicks
Joined: Oct 2000
Posts: 3,010
Likes: 1
From: Sweden/Stockholm
Re: open vs closed mode. (bill mcdonald)
well I know that car always goes better when its cold. But when my car gets hot the SOTP feel is alot less. Its like i loose 50 hp. :/
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
2027 Corvette vs The World: Every Model vs Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
5 MOST and 5 LEAST Popular Corvette Model Years in History!
Joe Kucinski
2027 Corvette Buyer's Guide: Everything You Need to Know!
Joe Kucinski
10 Things C8 Corvette Owners Hate (But Won't Tell You)
Joe Kucinski
10 Best Corvettes Coming to Barrett-Jackson Palm Beach 2026!
Brett Foote
Every Corvette Grand Sport Explained! (C2, C4, C6, C7, & C8)
Joe Kucinski
Grand Sport & Grand Sport X Launch Alongside All-New 535hp LS6 V8!
Michael S. Palmer
5 Reasons Bad Drivers Crash & 5 Ways to Avoid a Costly Mistake!
Joe Kucinski
Team Owner
Joined: Sep 2001
Posts: 62,067
Likes: 1,723
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Re: open vs closed mode. (devilfish)
I'm not sure about the sensor stuff, but i dont think it will even run w/o an O2 sensor sending signals back to the ECM.
Racer
Joined: Jul 2002
Posts: 304
Likes: 0
From: Plant City Fl.
Re: open vs closed mode. (devilfish)
Generally a bad cat won't show up until it's hot as you described. I have run into bad cats. many many times, and the cars all acted just like you have desribed. Just an educated guess though :)