Question about Long term fuel trims
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Question about Long term fuel trims
I understand that when the long fuel trim line is high on the positive side (+21 in my case) it means that there is too much air going into the engine and the ECU is compensating by adding more fuel, but what does it mean when one of the fuel term trim lines is normal (around 0) and the second long term fuel line is +21 ? my car is 2007 ford explorer sport trac.
btw there are no error codes and the check engine light is off.
Thanks.
btw there are no error codes and the check engine light is off.
Thanks.
Junior User
Joined: Sep 2017
Posts: 87
Likes: 3
I understand that when the long fuel trim line is high on the positive side (+21 in my case) it means that there is too much air going into the engine and the ECU is compensating by adding more fuel, but what does it mean when one of the fuel term trim lines is normal (around 0) and the second long term fuel line is +21 ? my car is 2007 ford explorer sport trac.
btw there are no error codes and the check engine light is off.
Thanks.
btw there are no error codes and the check engine light is off.
Thanks.
Logistics Pro
Joined: Jun 2009
Posts: 4,817
Likes: 83
From: Cedar Rapids, IA
Is the engine running roughly at all? Typically if you have a vacuum leak or a fuel injector that is not functioning properly you'll feel it as a misfire. And you can have a slight misfire that will not trigger a check engine light or active diagnostic code. You might have an intake manifold that is leaking, a fuel injector that is not functioning properly, a PCV elbow that is leaking (I don't recall which bank that typically effects first), a valve that is bad, or possibly an oxygen sensor that is not reading correctly.
Does your Sport Trac have the 4.0L SOHC V6 engine?
-Rod
Does your Sport Trac have the 4.0L SOHC V6 engine?
-Rod
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New User
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Is the engine running roughly at all? Typically if you have a vacuum leak or a fuel injector that is not functioning properly you'll feel it as a misfire. And you can have a slight misfire that will not trigger a check engine light or active diagnostic code. You might have an intake manifold that is leaking, a fuel injector that is not functioning properly, a PCV elbow that is leaking (I don't recall which bank that typically effects first), a valve that is bad, or possibly an oxygen sensor that is not reading correctly.
Does your Sport Trac have the 4.0L SOHC V6 engine?
-Rod
Does your Sport Trac have the 4.0L SOHC V6 engine?
-Rod
Do you have any suggestions on what should I check?
Logistics Pro
Joined: Jun 2009
Posts: 4,817
Likes: 83
From: Cedar Rapids, IA
Yep, checking the easy stuff first, as suggested above, is the place to start. If you have the ability to do a smoke test, that is also a good tool to help locate a vacuum leak. Beyond that, it's pretty much what was suggested above, checking for a fuel injector that maybe isn't opening, replacing the upstream oxygen sensors, and performing a cylinder leak down test to see if you have a valve or two that is not properly closing.
Also, there are two different 4.0L V6 engines - one that's an overhead valve, and one that is SOHC. For what's already been suggested, it probably doesn't matter. But there may be folks who are aware of typical issues with one version over the other (such as PCV elbows that crack).
-Rod
Also, there are two different 4.0L V6 engines - one that's an overhead valve, and one that is SOHC. For what's already been suggested, it probably doesn't matter. But there may be folks who are aware of typical issues with one version over the other (such as PCV elbows that crack).
-Rod
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