02 sensor
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Joined: Jul 2008
Posts: 93
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From: Soperton Georgia
02 sensor
I've been having a problem with my stock 94 lt1. After driving for 8 to 10 miles, the engine begins to run rough and continues for several miles until the service engine light comes on. When the light comes on the engine levels out but the fuel economy goes south.
I scaned it with an OTC Genisis and came up with an 02 sensor running lean.
Why would the engine level off after the light comes on? If it is 02 sensor related, wouldn't it run rough all the time?
What do my fellow Vette owners think?
Jon Sr.
I scaned it with an OTC Genisis and came up with an 02 sensor running lean.
Why would the engine level off after the light comes on? If it is 02 sensor related, wouldn't it run rough all the time?
What do my fellow Vette owners think?
Jon Sr.
Drifting
Joined: Nov 2005
Posts: 1,324
Likes: 5
From: Charlotte NC
The reason the engine'levels out' is that once the lean exhaust is detected at the O2 (Left or right), the system begins operating in a closed loop mode. This simply means the air/fuel ratio is no longer variable, but is now fixed. This allows you to drive her, but she'll be getting really bad mileage and performance.
Things to check:
O2 sensors (Obviously). I'd replace them both, or the side reporting the lean state. You can also look to see if the connectors are secure and grounded.
Fuel pressure. This includes malfunctioning injectors.
Exhaust leaks. This was the case for me. I had not secured the cat to the manifold properly and had just enough blowing by to screw things up and coat the back of the car with soot.
I took this all from the FSM on my '93. There are other items to test, but I'd think those 3 would be primary. Also to note: DTC 44 indicates left, 64 is right.
Good Luck!
Things to check:
O2 sensors (Obviously). I'd replace them both, or the side reporting the lean state. You can also look to see if the connectors are secure and grounded.
Fuel pressure. This includes malfunctioning injectors.
Exhaust leaks. This was the case for me. I had not secured the cat to the manifold properly and had just enough blowing by to screw things up and coat the back of the car with soot.
I took this all from the FSM on my '93. There are other items to test, but I'd think those 3 would be primary. Also to note: DTC 44 indicates left, 64 is right.
Good Luck!
Safety Car
Joined: Oct 2007
Posts: 3,816
Likes: 0
From: :45 minutes from everywhere / E-I-E-I-O
I say for now to ignore the O2.
You say when the SES comes on, it seems to 'level off'. Are you SURE there's not a real light miss in the fire?
Give this thread a gander, and see if there's any common faults...
http://forums.corvetteforum.com/show....php?t=2069247
You say when the SES comes on, it seems to 'level off'. Are you SURE there's not a real light miss in the fire?
Give this thread a gander, and see if there's any common faults...
http://forums.corvetteforum.com/show....php?t=2069247
Instructor
Joined: Dec 2007
Posts: 156
Likes: 0
From: Powhatan Virginia
The reason the engine'levels out' is that once the lean exhaust is detected at the O2 (Left or right), the system begins operating in a closed loop mode. This simply means the air/fuel ratio is no longer variable, but is now fixed. This allows you to drive her, but she'll be getting really bad mileage and performance.
Things to check:
O2 sensors (Obviously). I'd replace them both, or the side reporting the lean state. You can also look to see if the connectors are secure and grounded.
Fuel pressure. This includes malfunctioning injectors.
Exhaust leaks. This was the case for me. I had not secured the cat to the manifold properly and had just enough blowing by to screw things up and coat the back of the car with soot.
I took this all from the FSM on my '93. There are other items to test, but I'd think those 3 would be primary. Also to note: DTC 44 indicates left, 64 is right.
Good Luck!
Things to check:
O2 sensors (Obviously). I'd replace them both, or the side reporting the lean state. You can also look to see if the connectors are secure and grounded.
Fuel pressure. This includes malfunctioning injectors.
Exhaust leaks. This was the case for me. I had not secured the cat to the manifold properly and had just enough blowing by to screw things up and coat the back of the car with soot.
I took this all from the FSM on my '93. There are other items to test, but I'd think those 3 would be primary. Also to note: DTC 44 indicates left, 64 is right.
Good Luck!
To a point-when the "Ck Engine" light comes on the system goes into a sort of "open loop"--all parameters are preset-- meaning the computer ignores input from the O2 sensors--"closed loop" is after engine warm up/operating temp and the computer is adjusting fuel mixture according to input from the O2 sensors---I would check the items mentioned in the previous post and as stated don't forget the injectors
Drifting
Joined: Jun 2002
Posts: 1,945
Likes: 41
From: Corinth TX
To a point-when the "Ck Engine" light comes on the system goes into a sort of "open loop"--all parameters are preset-- meaning the computer ignores input from the O2 sensors--"closed loop" is after engine warm up/operating temp and the computer is adjusting fuel mixture according to input from the O2 sensors---I would check the items mentioned in the previous post and as stated don't forget the injectorsHere is a good article on O2 sensors.
http://www.aa1car.com/library/o2sensor.htm
Thread Starter
Advanced
Joined: Jul 2008
Posts: 93
Likes: 0
From: Soperton Georgia
The reason the engine'levels out' is that once the lean exhaust is detected at the O2 (Left or right), the system begins operating in a closed loop mode. This simply means the air/fuel ratio is no longer variable, but is now fixed. This allows you to drive her, but she'll be getting really bad mileage and performance.
Things to check:
O2 sensors (Obviously). I'd replace them both, or the side reporting the lean state. You can also look to see if the connectors are secure and grounded.
Fuel pressure. This includes malfunctioning injectors.
Exhaust leaks. This was the case for me. I had not secured the cat to the manifold properly and had just enough blowing by to screw things up and coat the back of the car with soot.
I took this all from the FSM on my '93. There are other items to test, but I'd think those 3 would be primary. Also to note: DTC 44 indicates left, 64 is right.
Good Luck!
Things to check:
O2 sensors (Obviously). I'd replace them both, or the side reporting the lean state. You can also look to see if the connectors are secure and grounded.
Fuel pressure. This includes malfunctioning injectors.
Exhaust leaks. This was the case for me. I had not secured the cat to the manifold properly and had just enough blowing by to screw things up and coat the back of the car with soot.
I took this all from the FSM on my '93. There are other items to test, but I'd think those 3 would be primary. Also to note: DTC 44 indicates left, 64 is right.
Good Luck!
I put the car on my lift this afternoon and looked underneath, checked the wires going to the 02s and just did a good underneath check. Nothing seems to be wrong. I did notice my car has two 02s on each exhaust. Can't remember which code the scanner gave but will recheck tomorrow.
The car has 90,000+ on the clock with the original injectors and has never given any trouble.
Thanks, will update soon.
Thread Starter
Advanced
Joined: Jul 2008
Posts: 93
Likes: 0
From: Soperton Georgia
Have the injectors ever been replaced? IF not, how many miles do you have on them. I was reading that you should replace your O2 sensors My car was doing the exact same thing and I pulled them and they looked like crap. I put in new ones and the car runs great. Fuel mileage went up as well.
Here is a good article on O2 sensors.
http://www.aa1car.com/library/o2sensor.htm
Here is a good article on O2 sensors.
http://www.aa1car.com/library/o2sensor.htm
Looks like new 02 sensors are scheduled.
Thanks
Thread Starter
Advanced
Joined: Jul 2008
Posts: 93
Likes: 0
From: Soperton Georgia
I say for now to ignore the O2.
You say when the SES comes on, it seems to 'level off'. Are you SURE there's not a real light miss in the fire?
Give this thread a gander, and see if there's any common faults...
http://forums.corvetteforum.com/show....php?t=2069247
You say when the SES comes on, it seems to 'level off'. Are you SURE there's not a real light miss in the fire?
Give this thread a gander, and see if there's any common faults...
http://forums.corvetteforum.com/show....php?t=2069247
The car stumbles and shudders like a miss until the SES goes out then will run like a B. O. H.
I just posted the mileage on the clock and from what I can see it's still running on all the factory hardware.
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Safety Car
Joined: Oct 2007
Posts: 3,816
Likes: 0
From: :45 minutes from everywhere / E-I-E-I-O
Until you solve this, you'd better keep the pedal down pretty far - the fuel is gonna' get delivered anyway if you use it or not, and if it ALL is not burned, guess what gets fouled with soot in the EGR, exhaust, cats, etc.,... YUP.
Clay you need to keep that in mind too!
Thread Starter
Advanced
Joined: Jul 2008
Posts: 93
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From: Soperton Georgia
Just scanned again. Codes read as follows.
63 (bank 2 Right heated 02 sensor circuit).
64 (bank 2 Right heated 02 sensor lean).
I may be loosing my mind but I'm almost positive, the first scan said left instead of right.
63 (bank 2 Right heated 02 sensor circuit).
64 (bank 2 Right heated 02 sensor lean).
I may be loosing my mind but I'm almost positive, the first scan said left instead of right.