Oil fouled 02 sensor????
Thread Starter
Burning Brakes
Joined: Nov 2002
Posts: 1,188
Likes: 266
From: Huntington Beach CA
Oil fouled 02 sensor???? Code 44
So, I keep getting code 44, fairly predictably when driving my car (1990 L98 coupe). I've also noticed a major decrease in fuel mileage (about 9-10 mpg city) and I can smell fuel when I shut the car off. I have been trying to figure out this problem for quite some time now.
I have done the following in order to track down this issue:
1. Replaced the 02 sensor twice
2. Replaced the female side of the connector to the 02 sensor
3. Checked for vacuum leaks
4. Replaced a vacuum hose running to the cruise control (which doesn't work either) from the brake pedal switch.
5. Replaced the IAC
6. Cleaned throttle body
.....and it still comes back. I have read that an oil contaminated wire can cause erroneous 02 sensor readings. Is this possible? If so, how far down stream, from the connector itself, would oil affect the 02 sensor's performance? There is quite a bit of oil on the section of the wire that is hanging from the firewall. I believe it may have come from when my oil pressure sending unit failed a few years back.
Any other ideas on where I can check next would be appreciated. I will clean off the wire, as well as I can tonight with Carb Cleaner.
Thanks in advance!
I have done the following in order to track down this issue:
1. Replaced the 02 sensor twice
2. Replaced the female side of the connector to the 02 sensor
3. Checked for vacuum leaks
4. Replaced a vacuum hose running to the cruise control (which doesn't work either) from the brake pedal switch.
5. Replaced the IAC
6. Cleaned throttle body
.....and it still comes back. I have read that an oil contaminated wire can cause erroneous 02 sensor readings. Is this possible? If so, how far down stream, from the connector itself, would oil affect the 02 sensor's performance? There is quite a bit of oil on the section of the wire that is hanging from the firewall. I believe it may have come from when my oil pressure sending unit failed a few years back.
Any other ideas on where I can check next would be appreciated. I will clean off the wire, as well as I can tonight with Carb Cleaner.
Thanks in advance!
Last edited by REDEVIL; Feb 28, 2007 at 06:21 PM.
Melting Slicks
Joined: Feb 2005
Posts: 2,135
Likes: 0
From: Sebastian Florida
St. Jude Donor '06
They are going bad, because you are probably running very rich. Check your injectors for one that is stuck open or your FP is to high, which will cause to much gas to be dumped into the cylinder. Or your computer might have bit the dust, do you have any other codes?
Thread Starter
Burning Brakes
Joined: Nov 2002
Posts: 1,188
Likes: 266
From: Huntington Beach CA
How can I check my injectors to see if one is stuck?
But, if the injector was bad and leaking, then wouldn't it cause a rich condition (code 45) and not a lean condition (code 44)? I take it as the 02 sensor sensing lean and then the fuel system overcompensating because of this lean condition, resulting in dumping too much fuel and causing the fuel smell and poor gas mileage. Does this sound reasonable?
Heel & Toe
Joined: Jan 2007
Posts: 20
Likes: 0
From: southaven ms
take a temp reading of the exhaust manifolds.
the sensor is showing a lean condition and running in open loop.
check the voltage coming from the o2 sensor and ohm the engine coolant temp sensor.(by the a/c compressor).
the o2 sensor's starts operating around 600*f.
i dont know what the ohm's on the coolant sensor should be or the supply voltage
i would start by checking it with the engine cold and see if it changes as the engine warms up.
you could maybe jump the connection with a paper clip and see what happens.
the sensor is showing a lean condition and running in open loop.
check the voltage coming from the o2 sensor and ohm the engine coolant temp sensor.(by the a/c compressor).
the o2 sensor's starts operating around 600*f.
i dont know what the ohm's on the coolant sensor should be or the supply voltage
i would start by checking it with the engine cold and see if it changes as the engine warms up.
you could maybe jump the connection with a paper clip and see what happens.
Melting Slicks
Joined: Feb 2005
Posts: 2,135
Likes: 0
From: Sebastian Florida
St. Jude Donor '06
I don't have any other codes. The car runs great, smooth idle and no power loss.
How can I check my injectors to see if one is stuck?
But, if the injector was bad and leaking, then wouldn't it cause a rich condition (code 45) and not a lean condition (code 44)? I take it as the 02 sensor sensing lean and then the fuel system overcompensating because of this lean condition, resulting in dumping too much fuel and causing the fuel smell and poor gas mileage. Does this sound reasonable?
How can I check my injectors to see if one is stuck?
But, if the injector was bad and leaking, then wouldn't it cause a rich condition (code 45) and not a lean condition (code 44)? I take it as the 02 sensor sensing lean and then the fuel system overcompensating because of this lean condition, resulting in dumping too much fuel and causing the fuel smell and poor gas mileage. Does this sound reasonable?
2 ways to check your injectors, get a fuel pressure gauge and put it on the car, then start the car and let it idle for about 2-3 minutes, then turn it off. Watch the guage, if you lose more than 3-5 psi over say 4-6 minutes, then you have a leaking or stuck injector.
The other is to take the fuel rail off the manifold and turn the key to the ON position(not started) and see if you see fuel come out of a injector.
Thread Starter
Burning Brakes
Joined: Nov 2002
Posts: 1,188
Likes: 266
From: Huntington Beach CA
Yes, you could have a bad wire or your connector could be bad. Check these before you go replacing parts. Do not go throwing parts at the problem, your o2 might just be a symptom and not the real problem.
2 ways to check your injectors, get a fuel pressure gauge and put it on the car, then start the car and let it idle for about 2-3 minutes, then turn it off. Watch the guage, if you lose more than 3-5 psi over say 4-6 minutes, then you have a leaking or stuck injector.
The other is to take the fuel rail off the manifold and turn the key to the ON position(not started) and see if you see fuel come out of a injector.
2 ways to check your injectors, get a fuel pressure gauge and put it on the car, then start the car and let it idle for about 2-3 minutes, then turn it off. Watch the guage, if you lose more than 3-5 psi over say 4-6 minutes, then you have a leaking or stuck injector.
The other is to take the fuel rail off the manifold and turn the key to the ON position(not started) and see if you see fuel come out of a injector.
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
With a code 44 (lean) I would be looking for unmeter air entering the exhaust before the O2 sensor. The sensor is seeing more oxygen in the exhaust stream sending a false reading and the ECM is trying compensate by dumping fuel. Exhaust leak or improper function of the AIR system.
You can pull the spark plugs and see if any are wet. That doesn't really mean a injector is leaking, but could mean a weak spark or no spark, but with the description "The car runs great, smooth idle and no power loss" I assume you don't have a problem with leaky injector or spark. Never hurts to look though.
You can pull the spark plugs and see if any are wet. That doesn't really mean a injector is leaking, but could mean a weak spark or no spark, but with the description "The car runs great, smooth idle and no power loss" I assume you don't have a problem with leaky injector or spark. Never hurts to look though.
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
This is from AGENT 86's pdf's
http://members.shaw.ca/corvette86/Code%2044.pdf
Check to make sure the O2 sensor wiring is connected good and is not grounding on the exhaust.
http://members.shaw.ca/corvette86/Code%2044.pdf
Check to make sure the O2 sensor wiring is connected good and is not grounding on the exhaust.
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Thread Starter
Burning Brakes
Joined: Nov 2002
Posts: 1,188
Likes: 266
From: Huntington Beach CA
This is from AGENT 86's pdf's
http://members.shaw.ca/corvette86/Code%2044.pdf
Check to make sure the O2 sensor wiring is connected good and is not grounding on the exhaust.
http://members.shaw.ca/corvette86/Code%2044.pdf
Check to make sure the O2 sensor wiring is connected good and is not grounding on the exhaust.
Tonight I cleaned off the 02 sensor wire and repositioned the wire itself. When I replaced the female side of the connector, I had quite a bit of slack in the wire and I think it may have been touching the sheet metal close to the wheel well. I rerouted the wire and made sure it wasn't touching any metal. I then drove the car for about 30 minutes, and no code. I even tried to moniter the fuel mileage and it seemed to be back up.
The reason I replaced the female side of the connection in the first place is that I was getting the same code, and I noticed that the connector was indeed contacting the exhaust manifold and the connector was melted. I then replaced the connector, but by having the slack in the wire, it allowed it to ground (I believe). I'm still not going to count my chickens though. I'll find out tomorrow when I drive more.
Thanks again.
Thread Starter
Burning Brakes
Joined: Nov 2002
Posts: 1,188
Likes: 266
From: Huntington Beach CA
It still doesn't make much sense to me. Because how can a wire ground out if the outside insulation of the wire is touching metal? Wouldn't the exposed wire have to be contacting a ground? Or are 02 sensors more unstable?
Burning Brakes
Joined: Nov 2005
Posts: 848
Likes: 1
From: 1992 LT1 6 speed Cayman Islands
You may have temporarely or perminantly fixed the problem when you repositioned the wire if there was a bad connection inside the insulation and by moving the wire you may have caused the two ends of the wore to touch again. As the code disappeared after you worked on the wire, I would look here again ifthe code comes back
Thread Starter
Burning Brakes
Joined: Nov 2002
Posts: 1,188
Likes: 266
From: Huntington Beach CA
the dreaded code 44 came back this morning. It was raining outside, so I wonder that has something to do with it. Maybe the 02 sensor isn't getting a good ground when it's wet. How would I ever be able to find that out?
fwiw, I never got this code until I came up to Seattle (Land of non-stop rain). When I was back in California it was never there. Thank God I'm going back in June....I hate this place.
fwiw, I never got this code until I came up to Seattle (Land of non-stop rain). When I was back in California it was never there. Thank God I'm going back in June....I hate this place.
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
I hope you have a factory service manual. You are going to need to check the wiring and connections. The FSM will tell you where the wire goes on the ECM connections and what color. Also the steps to take to troubleshoot it.
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
Fuel contamination: water even in small amounts, near the in-tank fuel pump inlet can be delivered to the injectors. The water causes a lean condition and can set a code 44.
I might would replace the gas cap and inspect very closely that there is not a way for water to enter the tank....see if the rubber boot drain is clogged. Even dump a bottle of HEET in the tank to remove any water in there.
Thread Starter
Burning Brakes
Joined: Nov 2002
Posts: 1,188
Likes: 266
From: Huntington Beach CA
From the last post I think you might have found the possible problem.
Fuel contamination: water even in small amounts, near the in-tank fuel pump inlet can be delivered to the injectors. The water causes a lean condition and can set a code 44.
I might would replace the gas cap and inspect very closely that there is not a way for water to enter the tank....see if the rubber boot drain is clogged. Even dump a bottle of HEET in the tank to remove any water in there.
Fuel contamination: water even in small amounts, near the in-tank fuel pump inlet can be delivered to the injectors. The water causes a lean condition and can set a code 44.
I might would replace the gas cap and inspect very closely that there is not a way for water to enter the tank....see if the rubber boot drain is clogged. Even dump a bottle of HEET in the tank to remove any water in there.
Thread Starter
Burning Brakes
Joined: Nov 2002
Posts: 1,188
Likes: 266
From: Huntington Beach CA
Update. I have since given up trying to figure out this problem. I took my car to Corvettes of Auburn in Auburn, WA earlier this week. I'm also having them replace the stock front y-pipe with a new one w/o pre-cats and a new center main cat....but that is a different story.
Recently, in addition to the Code 44 I've been getting Code 32. They cannot seem to duplicate the 44 code since they've had it, rather they are trying to track down the 32. They replaced the egr solenoid...didn't fix it. They also said the vacuum line running to the egr was deteriorated and replaced it. Also, they mentioned that the vacuum line running from the EGR to the throttle body was unplugged. I have noticed in the past that this will come undone and I have to put it back on. I don't know the status of it yet, but it seems like they are having a tough time with this. The problem is that the longer it stays in the shop the thinner my wallet gets.
Now, if the vacuum line to the egr was in fact not holding enough vacuum to operate the solenoid, that could cause a lean condition correct? I think I read that in the service manual.
Recently, in addition to the Code 44 I've been getting Code 32. They cannot seem to duplicate the 44 code since they've had it, rather they are trying to track down the 32. They replaced the egr solenoid...didn't fix it. They also said the vacuum line running to the egr was deteriorated and replaced it. Also, they mentioned that the vacuum line running from the EGR to the throttle body was unplugged. I have noticed in the past that this will come undone and I have to put it back on. I don't know the status of it yet, but it seems like they are having a tough time with this. The problem is that the longer it stays in the shop the thinner my wallet gets.
Now, if the vacuum line to the egr was in fact not holding enough vacuum to operate the solenoid, that could cause a lean condition correct? I think I read that in the service manual.
Thread Starter
Burning Brakes
Joined: Nov 2002
Posts: 1,188
Likes: 266
From: Huntington Beach CA
Well, the egr solenoid was not the problem. They determined that the vapor canister and purge solenoid were both inoperative. I replaced the vapor canister and the solenoid just arrived today. I will replace it tonight, but for some reason I do not think this is going to fix the issue. After replacing the canister and driving around for a few days the code 44 keeps reappearing.
Does it sound like maybe a bad ground to the ECM or a faulty ECM? where is the ECM grounded?
Does it sound like maybe a bad ground to the ECM or a faulty ECM? where is the ECM grounded?
