Does this have anything to do with code 311?
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Does this have anything to do with code 311?
So the CEL came on this past weekend and it showed 172 as a code in memory. And code 311 for KOER test.
I replaced the O2 sensor and that fixed code 172 and took my MPG from 9.5 to 12.5.
But I'm stumped with this 311 code. Hayne's manual doesn't help at all, they only care about the little engines. So I was checking for broken vacuum lines and what not, but couldn't find any. Other than this caught my eye.
That's over on the passenger fender. I know it has something to do with the smog pump, but I'm not sure what it does, or if it needs a hose on the left side.
1997 F250 460V8 E40D
I replaced the O2 sensor and that fixed code 172 and took my MPG from 9.5 to 12.5.
But I'm stumped with this 311 code. Hayne's manual doesn't help at all, they only care about the little engines. So I was checking for broken vacuum lines and what not, but couldn't find any. Other than this caught my eye.
That's over on the passenger fender. I know it has something to do with the smog pump, but I'm not sure what it does, or if it needs a hose on the left side.
1997 F250 460V8 E40D
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From looking at the definition of Code 311, I conjecture that it gets set as a result of a self-test. The computer tries to divert air to the right side manifold, but the right side oxygen sensor still indicates "rich", or continues to switch rich/lean. It should go full lean due to the added air. The computer complains because the diverter valve seems to have had no effect.
Look for broken hoses or blocked piping in the pathway from the air pump to the back of the head or manifold. Also check the diverter valve and vacuum plumbing to the two air pump control solenoids.
I don't have a 460, and don't recognize the object in the picture. Sorry.
Look for broken hoses or blocked piping in the pathway from the air pump to the back of the head or manifold. Also check the diverter valve and vacuum plumbing to the two air pump control solenoids.
I don't have a 460, and don't recognize the object in the picture. Sorry.
Elder User
Joined: Sep 2004
Posts: 941
Likes: 4
From looking at the definition of Code 311, I conjecture that it gets set as a result of a self-test. The computer tries to divert air to the right side manifold, but the right side oxygen sensor still indicates "rich", or continues to switch rich/lean. It should go full lean due to the added air. The computer complains because the diverter valve seems to have had no effect.
Look for broken hoses or blocked piping in the pathway from the air pump to the back of the head or manifold. Also check the diverter valve and vacuum plumbing to the two air pump control solenoids.
I don't have a 460, and don't recognize the object in the picture. Sorry.
Look for broken hoses or blocked piping in the pathway from the air pump to the back of the head or manifold. Also check the diverter valve and vacuum plumbing to the two air pump control solenoids.
I don't have a 460, and don't recognize the object in the picture. Sorry.
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Well I was at ford today, and they said that that was a muffler type device and doesn't need a hose on it.
I also asked them about code 311 and they said since it only showed up on a KOER test to not worry about it till it turns the check engine light on...
Could it be because I just put in the O2 sensor 0 miles and 5 minutes before I ran the test? Do 02 sensors break in?
I also asked them about code 311 and they said since it only showed up on a KOER test to not worry about it till it turns the check engine light on...
Could it be because I just put in the O2 sensor 0 miles and 5 minutes before I ran the test? Do 02 sensors break in?
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Oxygen sensors do not "break in". The computer does need to re-learn its fuel control strategy.
Whenever you change the oxygen sensors, MAP sensor, exhaust piping, fix vacuum leaks, clean the IAC, change the TPS, etc, you should disconnect the battery for 5 minutes, then allow the computer to re-learn. This will hasten its recognition of the new-found correct sensors, rather than having to "wear off" incorrect material learned from the old, bad sensors.
Whenever you change the oxygen sensors, MAP sensor, exhaust piping, fix vacuum leaks, clean the IAC, change the TPS, etc, you should disconnect the battery for 5 minutes, then allow the computer to re-learn. This will hasten its recognition of the new-found correct sensors, rather than having to "wear off" incorrect material learned from the old, bad sensors.
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