open loop
Le Mans Master
Joined: Jan 2003
Posts: 8,596
Likes: 19
From: Portland Oregon
Originally Posted by steve1ph2
which sensors on my `90 does the ecm rely on during open loop cold start?
Drifting
Joined: Apr 2003
Posts: 1,379
Likes: 4
From: rome ny
Originally Posted by tjwong
Actually the ECM only needs to know ECT. Even when the engine is warm or hot it will start in open loop until it sees the O2 sensors switch from high to low. Also in some strategies there is a closed loop delay timer that has to be satisfied as well. The strategy also includes a minimum engine coolant temp (ECT) to be satisfied before allowing closed loop operation.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
I know that the ECM looks at the TPS, because if you floor the throttle, you put the ECM in the "clear flood" mode. I don't know what other influence it could have on a cold start. I would say, too, that it may depend somewhat on what you mean by "not working". No signal at all would certainly set a code.
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Safety Car
Joined: Apr 2003
Posts: 3,793
Likes: 9
From: VA
Originally Posted by steve1ph2
which sensors on my `90 does the ecm rely on during open loop cold start?
Thread Starter
Burning Brakes
Joined: Jun 2004
Posts: 752
Likes: 0
From: richardson tx
Originally Posted by bigcityvette
didnt you just swap o2 sensors?
Problems? After the o2 swap????????????
Problems? After the o2 swap????????????
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Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by mos90
what if your iac is not working.. that will effect cold start..
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Burning Brakes
Joined: Jun 2004
Posts: 752
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From: richardson tx
the iac is fine and works iv already had problems with that in the past and am versed on its operation. fixing to go to work will be back at 7:30p or 11:30p central time thanks.
Le Mans Master
Joined: Feb 2000
Posts: 9,715
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From: Kempner Texas
This is one of those things that is probably year specific, but for the 86, when the engine is first started and is in open loop it ignores 02 feedback and uses input from the coolant temp sensor and the TPS to calculate the air/fuel ratio.
The IAC isn't in the picture because the engine will actually start and run with the IAC disconnected.
In order for it to go into closed loop, as someone already posted, a few conditions have to be met:
02 activity/cross counts; this indicates it has reached a min of 600*F
coolant temp is above about 104* F
engine has run for a specified amount of time
The specific conditions (like how long the engine must run) probably differs by engine. For the same year, 'Y' bodies probably differ from 'F' body cars; 86s probably differ from 89s, too, etc.
Jake
The IAC isn't in the picture because the engine will actually start and run with the IAC disconnected.
In order for it to go into closed loop, as someone already posted, a few conditions have to be met:
02 activity/cross counts; this indicates it has reached a min of 600*F
coolant temp is above about 104* F
engine has run for a specified amount of time
The specific conditions (like how long the engine must run) probably differs by engine. For the same year, 'Y' bodies probably differ from 'F' body cars; 86s probably differ from 89s, too, etc.
Jake
Last edited by JAKE; Apr 14, 2005 at 05:20 PM.
Thread Starter
Burning Brakes
Joined: Jun 2004
Posts: 752
Likes: 0
From: richardson tx
million dollar question. what is making it stumble and hesitate ( idles fine ) when the o2 heats up? and run perfect but rich with the o2 unplugged? also to tell you the truth i belive this new heated 02 is better than the factory one cause actually the car runs worse with this one than it did with the others.
Le Mans Master
Joined: Feb 2000
Posts: 9,715
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From: Kempner Texas
Originally Posted by steve1ph2
? also to tell you the truth i belive this new heated 02 is better than the factory one cause actually the car runs worse with this one than it did with the others.
Did you mean to type "is better . . ." or isn't better?
Just confused, again.
Jake
Instructor
Joined: Mar 2005
Posts: 208
Likes: 0
Originally Posted by steve1ph2
million dollar question. what is making it stumble and hesitate ( idles fine ) when the o2 heats up? and run perfect but rich with the o2 unplugged? also to tell you the truth i belive this new heated 02 is better than the factory one cause actually the car runs worse with this one than it did with the others.
Check the fuel injectors, assuming you are getting no codes.
Thread Starter
Burning Brakes
Joined: Jun 2004
Posts: 752
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From: richardson tx
Originally Posted by JAKE
??
Did you mean to type "is better . . ." or isn't better?
Just confused, again.
Jake
Did you mean to type "is better . . ." or isn't better?
Just confused, again.
Jake
