2000 Running Rich
Thread Starter
Cruising
Joined: May 2013
Posts: 13
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From: California
2000 Running Rich
My vette has recently started running rich. Over the past few months its fuel consumption has steadily gone up. At times when its cold it has a little black some coming out of the exhaust and smells rich, which would indicate a rich condition. I took it out for a drive a few nights ago and it was at 200 degrees (coolant temp). I accelerated it a little hard, and it had a cloud of smoke come out of the exhaust. I could notice it easily with it being night and illuminated by the driver behind me.
Tech Contributor
Joined: Jan 2004
Posts: 20,030
Likes: 289
From: Wylie TX --> Less is More, except under the hood !
A vacuum leak between your MAF and intake manifold has been known to cause bad MPG. (un-metered air)
Same with any of the various vacuum lines going into the intake manifold.
I'm no pro on which one causes what. Hopefully a pro will chime in.
Toque
Same with any of the various vacuum lines going into the intake manifold.
I'm no pro on which one causes what. Hopefully a pro will chime in.
Toque
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Melting Slicks
Joined: Jul 2012
Posts: 2,507
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Not when it's unmetered AFTER the MAF, that's the point. The MAF reports what it thinks entered the engine but more air has entered (i.e. a LEAN CONDITION).
The thing to CHECK it the O2 sensors, as they age they get "lazy" and do not respond quickly causing poor fuel consumption. Just caught the O2's on my truck last night with my laptop, one was not responding at all and the other was barely moving. Off to but some new ones today.
The thing to CHECK it the O2 sensors, as they age they get "lazy" and do not respond quickly causing poor fuel consumption. Just caught the O2's on my truck last night with my laptop, one was not responding at all and the other was barely moving. Off to but some new ones today.
Thread Starter
Cruising
Joined: May 2013
Posts: 13
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From: California
Ok. I have a friend that has a Mac scanner capable of graphing the sensors out puts. I will go first thing in the morning and take a look at the O2 sensors operation. I will post back what I find. Is there anything else I should look at while I have the scanner hooked up?
Melting Slicks
Joined: Jul 2012
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Ok. I have a friend that has a Mac scanner capable of graphing the sensors out puts. I will go first thing in the morning and take a look at the O2 sensors operation. I will post back what I find. Is there anything else I should look at while I have the scanner hooked up?
Burning Brakes
Joined: Dec 2003
Posts: 1,243
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From: Loveland CO
Old plugs? slow O2's? Sticky Injector? Dirty Maf? scanner will tell you what its seeing.. a vac leak that large should pop a P0171 lean code.. check pending/history codes. LTFT's and STFT's like mentioned above will tell you more. might want to try some FI cleaner.. I have had great luck with BG44K, and some MAF cleaner.
S
S
Thread Starter
Cruising
Joined: May 2013
Posts: 13
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From: California
About 2 weeks ago I ran a strong solution of sea foam directly to the injectors using the fuel pressure test port. It didn't help out any. It had good fuel pressure that was in specification.
Advanced
Joined: Mar 2013
Posts: 90
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From: Mission Viejo CA
A leaky injector can't be fixed with a Seafoam solution. A leaky injector stays 'open' longer than the computer specifies and as a result, you leak extra fuel into the cylinder.
They can also leak while the car is off. You might want to pull some plugs and see if any are discolored or 'wet' from the extra fuel...
They can also leak while the car is off. You might want to pull some plugs and see if any are discolored or 'wet' from the extra fuel...
Thread Starter
Cruising
Joined: May 2013
Posts: 13
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From: California
If an injector was leaking wouldn't the fuel rail loose pressure after the engine is shut off? I put a fuel pressure gauge on it and left it on the rail for ten minutes after I shut it off and it held good pressure.
Drifting
Joined: Oct 2011
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From: Olmsted Falls Ohio
St. Jude Donor '12 thru '24
Thread Starter
Cruising
Joined: May 2013
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From: California
I hooked up the scanner to the car yesterday and from what I found I believe it's a bad o2 sensor. The bank 2 sensor 2 was mainly staying around 65-80 mv. The bank 1 sensor 2 was fluctuating good between 70mv to aroun 180mv. At idle. When I accelerated the car all the sensors fluctuated alot except for the bank 2 sensor 2. How can 1 o2 sensor drive it as rich as it is? I checked the Maf and other sensors while I had it on the scanner and they were in specification.
Melting Slicks
Joined: Jul 2012
Posts: 2,507
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I hooked up the scanner to the car yesterday and from what I found I believe it's a bad o2 sensor. The bank 2 sensor 2 was mainly staying around 65-80 mv. The bank 1 sensor 2 was fluctuating good between 70mv to aroun 180mv. At idle. When I accelerated the car all the sensors fluctuated alot except for the bank 2 sensor 2. How can 1 o2 sensor drive it as rich as it is? I checked the Maf and other sensors while I had it on the scanner and they were in specification.
You should change BOTH front sensors while your there, they are maintenance items just like spark plugs, the front O2's are used for fuel adjustments, the rears are used for determining Catalyst efficiency so the front ones are the IMPORTANT ones.
You may have to disconnect the negative battery cable to get the Long Term settings to reset.
Last edited by 3boystoys; Jun 28, 2013 at 02:07 PM.
Thread Starter
Cruising
Joined: May 2013
Posts: 13
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From: California
I installed new o2 sensors and my fuel mileage has greatly improved. Thanks to everyone for your help and suggestions. Is there anything anyone recommends to put in to keep them clean?
