both banks lean
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both banks lean
Hi all,
My EB's idle is low, about 500-600 RPM's. Start up is fine, once it gets warm the idle drops off and acts as though it's dropped a couple of cyls. It has 150k on the motor, a new fuel and air filter, and a clean throttle body. The codes read #1 and 2 banks lean. Thanks in advance....
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You have a vacuum leak in your PCV line. The leak is in the rubber elbow that connects the PCV line to the intake manifold. The elbow is difficult to see but you can feel it. It is located on the top, center, rear of the engine. After time it rots, gets soft and develops a leak. This can be repaired in 5 minutes without tools. The part is about $25 to $50 depending on which engine. It gives you the entire PCV line but you only really need to replace the elbow. Good luck.
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Thanks...
You were dead on with this one. Just before my last trip I changed the PCV during a normal oil change and I guess I gorilla'd it up some. The mechanic that had the truck wanted to change my plugs, clean the induction system and mass airflow sensors. All items of PM that the truck could use, but as you and I know, not the problem. When he told me he had to take the fuel rail off to change the plugs and it would take him 4 hours to do, I had heard enough. What I like most about this forum is that it keeps shady mechanics honest. When he started talking to me about plugs and I asked him what a fouled plug had to do with a lean mixture that hasn't been ingited yet, his whole story changed, as you can imagine. Thanks again for your reply...
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From: York, PA
Actually a fouled plug can cause a lean O2 signal, since the O2 is measuring the oxygen content in the exhaust, ? what would happen then if the sparkplug is not firing the fuel in the combustion area?, no hydrocarbons have been expelled to take up the room of the oxygen in the combustion cylinder, the oxygen sensor does not know the difference between unburned fuel and oxygen, hence more oxygen is seen across the O2 sensor, lean signal.. Broken Wire
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I could be wrong, it happens a lot...
I know a lot about sensors (aircraft sensors to be exact) but very little about this particular vehicle and which sensors do what. I had just assumed that if you fouled a plug, you'd have more raw or uncombusted fuel in the exhaust indicating a rich mixture.
Regardless of how I understand the system to work, a fouled plug would be fouled at all RPM's right? I would at least have had some sort of depreciated performance in terms of power or gas mileage. I had none of these symptoms.
Further along those lines, they intended to charge me four hours of labor for changing spark plugs because the driver side fuel rail had to be removed to access the coil overs. I've done that same job in an hour and never removed the rails and I'm a shade tree.
I appreciate your optimism, it sounds to me like you're probably a automotive maintenance professional, and I'm sure a good and honest one. Unfortunately you'd be the exception rather than the rule in that profession and that's just a fact of life.
Regardless of how I understand the system to work, a fouled plug would be fouled at all RPM's right? I would at least have had some sort of depreciated performance in terms of power or gas mileage. I had none of these symptoms.
Further along those lines, they intended to charge me four hours of labor for changing spark plugs because the driver side fuel rail had to be removed to access the coil overs. I've done that same job in an hour and never removed the rails and I'm a shade tree.
I appreciate your optimism, it sounds to me like you're probably a automotive maintenance professional, and I'm sure a good and honest one. Unfortunately you'd be the exception rather than the rule in that profession and that's just a fact of life.
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From: York, PA
5.4, Yes I believe in myself to be an exception it this trade, I do it every day and have for 31 years, yes you are right that a fouled plug would lead you to believe rich mixture, but you have know that this sensor picks up on "oxygen" not unburned fuel, burn't fuel takes up the oxygen, so it is either to much oxygen or not enough oxygen going across the sensor, does not respond to the fuel. 4 hours is steep, I guess he was saying off the get go, he did not want to do it, I don't know if he should be called a shyster though, he just wanted to make it worth his time, this plug setup was not one of Fords better ideas, but they don't give to rats what we think, I am sure there will always be someone standing in line to pay his 4 hours also. I would also have to agree with your thinking on 'fouled'. Broken Wire
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