1985 - Is 16:1 normal at idle?
07-31-2005, 12:16 PM
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Le Mans Master
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1985 - Is 16:1 normal at idle?
I posted this over in Tech:
http://forums.corvetteforum.com/show....php?t=1149736
Very near stock setup. AFR in open loop = 12:1 -> 14:1.
Then in closed loop, at IDLE, climbs to a steady 16:1. Is this normal for an '85? Did GM tune for that much ECONOMY at idle?
http://forums.corvetteforum.com/show....php?t=1149736
Very near stock setup. AFR in open loop = 12:1 -> 14:1.
Then in closed loop, at IDLE, climbs to a steady 16:1. Is this normal for an '85? Did GM tune for that much ECONOMY at idle?
07-31-2005, 02:43 PM
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Originally Posted by Alvin
Are you watching a wideband?
If so, often at a idle the o2 sensor isn't satisfied and gives false lean readings.
If so, often at a idle the o2 sensor isn't satisfied and gives false lean readings.
08-01-2005, 12:30 AM
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Originally Posted by tjwong
Especially if the sensor is placed in the tail pipe tip and not in a bung. Also verify that the AIR pump diverter valve isn't diverting air into the catalyst.
08-01-2005, 12:32 AM
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St. Jude Donor '05
They still have a hard time at a idle. Mine is adjacent to the O2 and I shoot for 18:1 due to the cam overlap. The widebands don't always work well at a idle. Tune the idle with a vaccum gauge
08-01-2005, 12:33 AM
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Originally Posted by Alvin
Are you watching a wideband?
If so, often at a idle the o2 sensor isn't satisfied and gives false lean readings.
If so, often at a idle the o2 sensor isn't satisfied and gives false lean readings.
08-01-2005, 12:52 AM
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St. Jude Donor '05
My jeep reads 14.7 at the tail pipe.
They just are not accurate enough to read at idle, whats the point anyway, tune for vaccum and be done with it.
There are so many things that can mess with that sensor especially at a idle... Like it going cold, air pump coming on, exhaust leaks, etc. We are here telling you that seeinga high AFR at a idle isn't out of the ordinary
They just are not accurate enough to read at idle, whats the point anyway, tune for vaccum and be done with it.
There are so many things that can mess with that sensor especially at a idle... Like it going cold, air pump coming on, exhaust leaks, etc. We are here telling you that seeinga high AFR at a idle isn't out of the ordinary
08-01-2005, 11:35 PM
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Originally Posted by Alvin
My jeep reads 14.7 at the tail pipe.
They just are not accurate enough to read at idle, whats the point anyway, tune for vaccum and be done with it.
There are so many things that can mess with that sensor especially at a idle... Like it going cold, air pump coming on, exhaust leaks, etc. We are here telling you that seeinga high AFR at a idle isn't out of the ordinary
They just are not accurate enough to read at idle, whats the point anyway, tune for vaccum and be done with it.
There are so many things that can mess with that sensor especially at a idle... Like it going cold, air pump coming on, exhaust leaks, etc. We are here telling you that seeinga high AFR at a idle isn't out of the ordinary
08-02-2005, 12:15 AM
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..also at about 2500-3500 rpm the tach starts 'bouncing' back to like 2500 rpm. The engine is at about 3500 rpm bet the tach is going crazy.
08-02-2005, 12:43 AM
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St. Jude Donor '05
Do you have a misfire?
Stock cam or not, I do not like them for no-load and idle tuning. one of my personal cars has a 210/220 114.5 duration cam and even it requires like a 17:1 or else its a stinker.
Stock cam or not, I do not like them for no-load and idle tuning. one of my personal cars has a 210/220 114.5 duration cam and even it requires like a 17:1 or else its a stinker.
08-02-2005, 12:45 AM
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Originally Posted by Alvin
Do you have a misfire?
Stock cam or not, I do not like them for no-load and idle tuning. one of my personal cars has a 210/220 114.5 duration cam and even it requires like a 17:1 or else its a stinker.
Stock cam or not, I do not like them for no-load and idle tuning. one of my personal cars has a 210/220 114.5 duration cam and even it requires like a 17:1 or else its a stinker.
08-02-2005, 01:14 AM
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Originally Posted by Alvin
Do you get any popping while revving by anychance? Have you driven it yet?
Check to see where the BLM"s are. thats the key.
Check to see where the BLM"s are. thats the key.
08-03-2005, 12:21 AM
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Originally Posted by Alvin
Do you get any popping while revving by anychance? Have you driven it yet?
Check to see where the BLM"s are. thats the key.
Check to see where the BLM"s are. thats the key.
Had 3 control spark counts. Pulse width was about 1.4mS
Then hooked up EASE diagnostics and got some weird results. Had codes:
052 - calpak missing (nope, got a fresh GM version)
053 - over voltage
054 - Fuel pump voltage.
A/c request = on (big lie since it was off)
All this in Closed loop....
08-03-2005, 12:34 AM
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St. Jude Donor '05
Did you have a 108 while observing a High AFR?
If so you may have some sort of O2 failure. Usually when I see them fail they go lean, but anything is possilbe.
Did you say that you have chip burning equipment?
Try clearing the codes and see what comes back.
If so you may have some sort of O2 failure. Usually when I see them fail they go lean, but anything is possilbe.
Did you say that you have chip burning equipment?
Try clearing the codes and see what comes back.
08-03-2005, 12:51 AM
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St. Jude Donor '05
actually 108 means that the car is very fat and it can't pull any more fuel out. 160 is very lean, can't add any more fuel.
I suspect either a bad O2, (your using delco right?)
Misfire (can do funky things with O2 sensors)
Valve adjustment
Try swapping the o2's and see what happens.. If your wideband was reading 16:1 and your BLMS where in the >140's I would say your definately lean, right now your just getting a false signal from somewhere.
I suspect either a bad O2, (your using delco right?)
Misfire (can do funky things with O2 sensors)
Valve adjustment
Try swapping the o2's and see what happens.. If your wideband was reading 16:1 and your BLMS where in the >140's I would say your definately lean, right now your just getting a false signal from somewhere.
