Welcome to the North American Subaru Impreza Owners Club Tuesday December 12, 2017
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
Go Back   NASIOC > NASIOC Archives > NASIOC Archives > Technical Forum Archive

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads. 
Thread Tools Display Modes
Old 05-07-2000, 05:34 PM   #1
Scooby Specialist
Member#: 759
Join Date: Jan 2000
Chapter/Region: NESIC
Location: Warwick, RI
2012 Regal GS
2000 SV650

Question AFC work in closed loop?

Just wondering if the Apexi AFC affects fuel control while the ecu is reading off the O2 sensor? I know the computer reads off sensors such as water temp, MAF, O2 and others while adjusting fuel, but is one reading taken into consideration more than others? Lets say I lean the car out for light throttle highway driving to increase gas milage, would the computer even care that I messed with the MAF reading or would O2 sensor signals be more of what it is looking at? Just curious and used to working with carbs, so fuel injection confuses me sometimes.
* Registered users of the site do not see these ads.
Nat is offline  
Sponsored Links
* Registered users of the site do not see these ads.
Old 05-07-2000, 07:19 PM   #2
Scooby Specialist
Member#: 52
Join Date: Jun 1999
Location: Naperville, IL
2005 Legacy GT
98 BMW 540i LS2/T56


During closed loop the computer will constantly be trying to make the engine run the way the ecu is programmed. If you modify the MAF to make the car think there is more air, the ecu will still try to get the fuel mixture taht it wants to see from the o2 sensor. If you make huge changes, the ecu may not be able to correct them, but then you will get a CE light. It may be possible to make some small changes during closed loop, but not very much.
rao is offline  
Old 05-07-2000, 07:26 PM   #3
[email protected]
Member#: 67
Join Date: Jul 1999
Chapter/Region: SCIC
Location: San Diego, CA
1999 Outlasting
the competition.


Dont hold me to this but from what i've been told the
ecu runs in a open loop until it reaches 100% full throttle.. there fore you just have to drive at 99.9999% and you'll be fine
tom@kartboy is offline  
Old 05-07-2000, 11:19 PM   #4
Scooby Newbie
Member#: 143
Join Date: Aug 1999
Location: Kanata, ON, Canada
1999 Impreza 2.5RS
Supercharged - and STOLEN


Actually, the ecu can run in open loop quite often.

In our cars little more than 60% throttle will snap it open.
It's in open on deceleration.
It'll be open when running cold.
There's a good chance it runs open at high RPMs - not sure though.
In 'limp mode', it probably runs open loop as well.

edekker is offline  

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
03 WRX bad cold start idle in closed loop / rich open loop fuelling toflaherty Open Source Reflashes 2 04-17-2010 10:06 AM
Stuck in closed loop fueling (i think)...need help!!! lowblow Factory 2.0L Turbo Powertrain (EJ Series Factory 2.0L Turbo) 15 08-16-2005 09:35 PM
compression numbers? knock in closed loop? deluxsti Factory 2.5L Turbo Powertrain (EJ Series Factory 2.5L Turbo) 12 08-14-2005 06:38 PM
ABC low boost in closed loop mode??? GMTarkin Engine Management & Tuning 2 08-03-2003 11:36 PM
Does S-AFC work in Closed Loop? SPeeDSiN Factory 2.0L Turbo Powertrain (EJ Series Factory 2.0L Turbo) 16 07-26-2002 12:36 PM

All times are GMT -4. The time now is 05:01 AM.

Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2017 Axivo Inc.
Copyright ©1999 - 2017, North American Subaru Impreza Owners Club, Inc.