C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Open VS closed loop.

Thread Tools
 
Search this Thread
 
Old Jul 3, 2003 | 06:45 AM
  #1  
Swede's Avatar
Swede
Thread Starter
Intermediate
 
Joined: Sep 2002
Posts: 43
Likes: 0
From: Kyrkhult Blekinge
Default Open VS closed loop.

Hello gurus!!
My car seems to go in open loop untill 130degr and the goes to closed loop and it stays there no matter what happends,,any suggestions ?? :confused:
Reply
Old Jul 3, 2003 | 07:22 AM
  #2  
Aaron71771's Avatar
Aaron71771
Le Mans Master
25 Year Member
Conversation Starter
All Eyes On Me
 
Joined: Jan 2000
Posts: 6,372
Likes: 21
From: Traverse City MI
Default Re: Open VS closed loop. (Swede)

It's normal for the car to go into closed loop once the engine reached operating temps. How do you know you are in closed loop all the time?
Reply
Old Jul 3, 2003 | 07:28 AM
  #3  
Swede's Avatar
Swede
Thread Starter
Intermediate
 
Joined: Sep 2002
Posts: 43
Likes: 0
From: Kyrkhult Blekinge
Default Re: Open VS closed loop. (Aaron71771)

I have datamaster hooked up and what i could see it is never going into other modes. I`am just a beginner to this.. :crazy:


[Modified by Swede, 1:28 PM 7/3/2003]
Reply
Old Jul 3, 2003 | 08:59 AM
  #4  
Lone Ranger's Avatar
Lone Ranger
Le Mans Master
10 Year Member
 
Joined: Feb 2002
Posts: 7,858
Likes: 2
Default Re: Open VS closed loop. (Swede)

That sounds normal for an '87 (L98). Once it goes into closed loop it should stay there unless you go WOT (Wide Open Throttle) then it should look to the WOT air/fuel tables for what air/fuel ratio to use instead of looking at the oxygen sensors for what air/fuel mixture to use. In closed loop under part-throttle (reading the oxygen sensors output) it should try to set 14.7:1 air/fuel mixture, that is the goal. That mixture is not best for WOT throttle because it will cook the valves from too much heat due to the air (oxygen) content at that mixture ratio. It has been said that the leanest the WOT mixture should be is 12.7:1 and no more.

Summary: I think what you are observing is nc (Normal Condition).
Reply
Old Jul 3, 2003 | 09:12 AM
  #5  
ski_dwn_it's Avatar
0ski_dwn_it
Former Vendor
 
Joined: Jun 2001
Posts: 7,204
Likes: 6
From: St Marys PA
Default Re: Open VS closed loop. (Lone Ranger)

That is fine. There are several parameters that need to be met before the car will go to closed loop. A few off the top of my head are.

1. O2 sensor must reach ~600*
2. The coolant must reach preset temp
3. The timers in the ECM must time out.

Also during WOT the open closed loop will remain in the closed position even at WOT. However the learn control will shut off during the run. And the BLM will lock on 128.

Your fine and have nothing to worry about. :cheers:
Reply
Old Jul 3, 2003 | 09:46 AM
  #6  
Swede's Avatar
Swede
Thread Starter
Intermediate
 
Joined: Sep 2002
Posts: 43
Likes: 0
From: Kyrkhult Blekinge
Default Re: Open VS closed loop. (ski_dwn_it)

Thanks!!
You are absolutly right both,,Thats me who is not understanding. When I hit the throttle I see when it changes from 14,73 to 12 and even go down to 11,23 for a while. Just another ques,,My AFGS gm/sec is not reaching ower 204,,I have some old results when I have been up to 233,,Is this something that is wrong ??? :confused:


[Modified by Swede, 3:47 PM 7/3/2003]
Reply
Old Jul 3, 2003 | 11:29 AM
  #7  
vader86's Avatar
vader86
Team Owner
20 Year Member
Liked
Loved
Community Favorite
 
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
Default Re: Open VS closed loop. (ski_dwn_it)

That is fine. There are several parameters that need to be met before the car will go to closed loop. A few off the top of my head are.

1. O2 sensor must reach ~600*
2. The coolant must reach preset temp
3. The timers in the ECM must time out.

Also during WOT the open closed loop will remain in the closed position even at WOT. However the learn control will shut off during the run. And the BLM will lock on 128.
I was wondering what all the parameters were. Do you know any others? Can the preset temp be changed with a chip program? How do those ECM timers work?
Reply
Old Jul 3, 2003 | 11:31 AM
  #8  
scorp508's Avatar
scorp508
Team Owner
Supporting Lifetime Gold
25 Year Member
Liked
Loved
Community Favorite
 
Joined: Mar 2000
Posts: 83,381
Likes: 87
From: Boston, MA
Default Re: Open VS closed loop. (vader86)

How do those ECM timers work?
Seconds after engine start.
Reply
Corvette Stories

The Best of Corvette for Corvette Enthusiasts

story-0

5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2

 Michael S. Palmer
story-1

2027 Corvette vs The World: Every Model vs Closest Competitor

 Joe Kucinski
story-2

10 Most Common Corvette Problems of the Last 20 Years!

 Joe Kucinski
story-3

5 MOST and 5 LEAST Popular Corvette Model Years in History!

 Joe Kucinski
story-4

2027 Corvette Buyer's Guide: Everything You Need to Know!

 Joe Kucinski
story-5

10 Things C8 Corvette Owners Hate (But Won't Tell You)

 Joe Kucinski
story-6

10 Best Corvettes Coming to Barrett-Jackson Palm Beach 2026!

 Brett Foote
story-7

Every Corvette Grand Sport Explained! (C2, C4, C6, C7, & C8)

 Joe Kucinski
story-8

Grand Sport & Grand Sport X Launch Alongside All-New 535hp LS6 V8!

 Michael S. Palmer
story-9

5 Reasons Bad Drivers Crash & 5 Ways to Avoid a Costly Mistake!

 Joe Kucinski
Old Jul 3, 2003 | 11:33 AM
  #9  
vader86's Avatar
vader86
Team Owner
20 Year Member
Liked
Loved
Community Favorite
 
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
Default Re: Open VS closed loop. (scorp508)

So if i just start the car, it would be like 5-10 sec and those timers would time out?
Reply
Old Jul 3, 2003 | 11:36 AM
  #10  
scorp508's Avatar
scorp508
Team Owner
Supporting Lifetime Gold
25 Year Member
Liked
Loved
Community Favorite
 
Joined: Mar 2000
Posts: 83,381
Likes: 87
From: Boston, MA
Default Re: Open VS closed loop. (vader86)

So if i just start the car, it would be like 5-10 sec and those timers would time out?
Its more than that. I forget what mine are set to. I have tunercat loaded at home though and can look if Jesse doesn't chime in.
Reply

Get notified of new replies

To Open VS closed loop.





All times are GMT -4. The time now is 04:33 AM.

story-0
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2

Slideshow: Should you buy a 2020-2026 Corvette or wait for 2027?

By Michael S. Palmer | 2026-04-22 10:08:58


VIEW MORE
story-1
2027 Corvette vs The World: Every Model vs Closest Competitor

Slideshow: 2027 Corvette lineup vs the world.

By Joe Kucinski | 2026-04-20 17:58:41


VIEW MORE
story-2
10 Most Common Corvette Problems of the Last 20 Years!

Slideshow: 10 major Corvette problems from the last 20 years.

By Joe Kucinski | 2026-04-14 16:37:05


VIEW MORE
story-3
5 MOST and 5 LEAST Popular Corvette Model Years in History!

Slideshow: 5 most and least popular Corvette model years.

By Joe Kucinski | 2026-04-08 13:25:01


VIEW MORE
story-4
2027 Corvette Buyer's Guide: Everything You Need to Know!

Slideshow: 2027 Corvette buyer's guide

By Joe Kucinski | 2026-04-17 16:41:08


VIEW MORE
story-5
10 Things C8 Corvette Owners Hate (But Won't Tell You)

Slideshow: 10 things C8 Corvette owners hate, but won't tell you.

By Joe Kucinski | 2026-04-01 18:36:07


VIEW MORE
story-6
10 Best Corvettes Coming to Barrett-Jackson Palm Beach 2026!

Slideshow: Should you add one of these incredible Corvettes to your garage?

By Brett Foote | 2026-04-01 18:14:05


VIEW MORE
story-7
Every Corvette Grand Sport Explained! (C2, C4, C6, C7, & C8)

Slideshow: Every Corvette Grand Sport explained

By Joe Kucinski | 2026-03-26 07:13:44


VIEW MORE
story-8
Grand Sport & Grand Sport X Launch Alongside All-New 535hp LS6 V8!

Slideshow: Breaking down the 2027 Grand Sport, Grand Sport X, Stingray, and LS6 V8.

By Michael S. Palmer | 2026-03-26 13:48:45


VIEW MORE
story-9
5 Reasons Bad Drivers Crash & 5 Ways to Avoid a Costly Mistake!

Slideshow: 5 reasons bad drivers crash sports cars & 5 ways to avoid a costly shame!

By Joe Kucinski | 2026-03-25 16:32:55


VIEW MORE