Newbie question re closed/open loops
Thread Starter
Drifting
Joined: Apr 2002
Posts: 1,817
Likes: 1
From: Hartland WI
Newbie question re closed/open loops
'88 auto
one of the diagonistic flow charts in the Helms manual says to
"Start engine and run until system goes "closed loop"
How do I know when it goes "closed loop"?
Thanks
one of the diagonistic flow charts in the Helms manual says to
"Start engine and run until system goes "closed loop"
How do I know when it goes "closed loop"?
Thanks
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
You can insert a bent paper clip or wire as a jumper into the the top, two right hand opening in the Assenbly Line Diagnostic Link (ALDL). These are the A&B terminals. The ALDL is located under the dash, right near where your right knee would be with you sitting in the driver's seat.
The Service Engine Soon light will begin to flash. It will flash at two and one half times per second to indicate OPEN LOOP and ONE TIME PER SECOND to indicate CLOSED LOOP.
Jake
The Service Engine Soon light will begin to flash. It will flash at two and one half times per second to indicate OPEN LOOP and ONE TIME PER SECOND to indicate CLOSED LOOP.
Jake
Thread Starter
Drifting
Joined: Apr 2002
Posts: 1,817
Likes: 1
From: Hartland WI
Originally Posted by steve9899
The usual way is to just let it warm up to operating temperature.
Which doesn't guarantee that its in closed loop, but that's really what the manual is telling you to do.
Which doesn't guarantee that its in closed loop, but that's really what the manual is telling you to do.
A ha - thats the answer I was looking for - easy! Thanks, even I can understand that much.
Team Owner
Joined: May 2002
Posts: 24,337
Likes: 25
From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
When is closed loop begun? Does the ecm look for a reading from the 02 sensor to see if it's heated up? Or is it based on coolant temp, or??? 
...or when my idle goes from rock solid to crappy?
...or when my idle goes from rock solid to crappy?
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Originally Posted by CentralCoaster
When is closed loop begun? Does the ecm look for a reading from the 02 sensor to see if it's heated up? Or is it based on coolant temp, or???
...or when my idle goes from rock solid to crappy?
...or when my idle goes from rock solid to crappy?
Once in closed loop, the ECM primarily uses 02 feed back, but also MAF, TPS, coolant temp info.
Before the system will go closed loop, several conditions must be met, like 02 voltage cross counts, count-down timer expired, minimum coolant temperature and maybe some other things I can't recall right now. There's a listing in the Shop Manual, but I don't have it in front of my now.
Jake
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