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2005 Ford Taurus SE Sedan 3.0L
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Discussion Starter #1
So, the weather turned a bit colder and now I'm getting the codes for banks 1 and 2 being too lean, so I'm guessing there is a small vacuum leak that rears it's head when it gets colder, as the idle tends to fluctuate slightly as well, every once in awhile it's drop below where it should normally idle and feel rough, but very rarely.

So I'm considering doing the smoke method to track down any leaks that there might be, for anyone else that may have done that, which is the best approach to doing that on this car, is there any particular hose you'd recommend using the pump the smoke into that would work best?

Hoping to finally get that issue tracked down, and it seems that's possibly the most likely culprit is a vacuum leak since I'm getting P0171 and 174 lean codes, but only in colder weather, but during the warmer months I wasn't getting the code, but the idle was still fluctuating, so if it's indeed that, it must be very minor and the cold just angers it, lol. Going to pull the ignition coil off this weekend and check the bottom of it to make sure it isn't heat cracked or anything as well, just to rule it out.

But thinking the smoke method is going to be the easier way to find the leak, just need to figure out which hose is the best candidate.

Thanks! And hope everyone is healthy and staying safe!
 

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I prefer watching fuel trims on a scan tool and using a propane torch that's unlit, as soon as find the leak, fuel trims will go way negative. If you insist on using smoke (which is difficult without a mechanic grade machine), make sure you block off the inlet of the intake tube where it connects to the air filter. I like using the hose that goes from the accordion portion before the MAF through the junction box on the firewall, pump the smoke in there and plug the hole where it normally connects to as well.
 

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I prefer watching fuel trims on a scan tool and using a propane torch that's unlit, as soon as find the leak, fuel trims will go way negative. If you insist on using smoke (which is difficult without a mechanic grade machine), make sure you block off the inlet of the intake tube where it connects to the air filter. I like using the hose that goes from the accordion portion before the MAF through the junction box on the firewall, pump the smoke in there and plug the hole where it normally connects to as well.
What do you block the inlet of the intake tube with? Newspaper or something?
 

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Engine's always run lean in cold weather because the air is denser, resulting in more air for the same amount of fuel; the reverse is true in hot weather. Of course, modern cars compensate for most (or all) of these temp variations, but on an older 'modern' car it's something to consider.

To block the intake hose, put a plastic bag over it and then clamp it back onto the air cleaner.
 

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So, the weather turned a bit colder and now I'm getting the codes for banks 1 and 2 being too lean, so I'm guessing there is a small vacuum leak that rears it's head when it gets colder, as the idle tends to fluctuate slightly as well, every once in awhile it's drop below where it should normally idle and feel rough, but very rarely.

So I'm considering doing the smoke method to track down any leaks that there might be, for anyone else that may have done that, which is the best approach to doing that on this car, is there any particular hose you'd recommend using the pump the smoke into that would work best?

Hoping to finally get that issue tracked down, and it seems that's possibly the most likely culprit is a vacuum leak since I'm getting P0171 and 174 lean codes, but only in colder weather, but during the warmer months I wasn't getting the code, but the idle was still fluctuating, so if it's indeed that, it must be very minor and the cold just angers it, lol. Going to pull the ignition coil off this weekend and check the bottom of it to make sure it isn't heat cracked or anything as well, just to rule it out.

But thinking the smoke method is going to be the easier way to find the leak, just need to figure out which hose is the best candidate.

Thanks! And hope everyone is healthy and staying safe!
Smoke can miss minor and hidden places where leaks can occur. What are your LTFT at zero and 2500 rpm (once the car is at driving temp) You can have an air leak that is not a vacuum leak. When, just for maintenance did you last clean your MAF?
. Propane or ether is better along with your scanner.

Tom in Dallas

Tom in Dallas
 

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2005 Ford Taurus SE Sedan 3.0L
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Discussion Starter #6
Smoke can miss minor and hidden places where leaks can occur. What are your LTFT at zero and 2500 rpm (once the car is at driving temp) You can have an air leak that is not a vacuum leak. When, just for maintenance did you last clean your MAF?
. Propane or ether is better along with your scanner.

Tom in Dallas

Tom in Dallas
Thank you for the info, and as for the MAF sensor, since it was the original, I went ahead and cleaned it, still had the same issue, so I replaced it, and kept the original as a backup.

And I just ran a test with my scantool tonight on the LTFT, and waited for the full operating temp before recording the numbers:

At idle:
Bank 1: 2.3%
Bank 2: 5.5%

2500RPM
Bank 1: 7%
Bank2: 11.7%

Those are the numbers I got from the live data.
 

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Discussion Starter #7 (Edited)
Ran a second test just to double check my numbers.

Idle was a bit different
B1: 5.5 %
B 2: 9.4%

The numbers at 2500 rpms were the same
B1: 7.0 %
B2 11.7%

With the idle ranging from about ~650-750

And interestingly enough, after about a week of the light being on, by the time I got done with checking it the second time the CEL had gone off, and I didn't clear it myself.
 

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Ran a second test just to double check my numbers.

Idle was a bit different
B1: 5.5 %
B 2: 9.4%

The numbers at 2500 rpms were the same
B1: 7.0 %
B2 11.7%

With the idle ranging from about ~650-750

And interestingly enough, after about a week of the light being on, by the time I got done with checking it the second time the CEL had gone off, and I didn't clear it myself.
Fuel trims bounce around as in the data attached. If they go high at idle but OK under power you have a likely vacuum leak. One side much different than the other, and you likely have some issue on one bank but not much vacuum issue on one bank only. Misfire will cause a false lean. As to %, any number after the decimal is just noise. For me, any number +/-10% will run just fine.
-chart-
 

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2005 Ford Taurus SE Sedan 3.0L
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Discussion Starter #9
Fuel trims bounce around as in the data attached. If they go high at idle but OK under power you have a likely vacuum leak. One side much different than the other, and you likely have some issue on one bank but not much vacuum issue on one bank only. Misfire will cause a false lean. As to %, any number after the decimal is just noise. For me, any number +/-10% will run just fine.
-chart-
I'm not quite sure what the normal LTFTs would be, and someone mentioned getting a reading of them at idle and at 2500 rpm, so I got up to operating temp, and took the first readings, then held 2500 rpm for about a minute and got the other readings.

And I did it again a second time just to double check to see how the readings would be, interesting part was the CEL went off whereas it's been on for over 2 weeks. Last year when it did it I believe I had a misfire code, but I can't remember what it was now, it's never done it again.

So based on the numbers should I be looking for a vacuum leak based on those numbers.

Also have a new ignition coil, and will probably do plugs/wires in the future, since I'm pretty sure those are the originals with 119k on them now. I've read the ignition coil could be cracked on the bottom, I haven't pulled it off yet to look, should probably do that this weekend and just change it out if it looks bad.

I also will be changing the fuel filter.

I do have one other theory, I think the brake booster may be leaking (very very minor and I've seen what looks like fluid, but I'll have to really get in there and double check), because I do have to add fluid every few months, so is it possible that could be the source of the issue, I'm pretty sure the booster has to do with the vacuum system as well with the lines running to it?
 

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I'm not quite sure what the normal LTFTs would be, and someone mentioned getting a reading of them at idle and at 2500 rpm, so I got up to operating temp, and took the first readings, then held 2500 rpm for about a minute and got the other readings.

And I did it again a second time just to double check to see how the readings would be, interesting part was the CEL went off whereas it's been on for over 2 weeks. Last year when it did it I believe I had a misfire code, but I can't remember what it was now, it's never done it again.

So based on the numbers should I be looking for a vacuum leak based on those numbers.

Also have a new ignition coil, and will probably do plugs/wires in the future, since I'm pretty sure those are the originals with 119k on them now. I've read the ignition coil could be cracked on the bottom, I haven't pulled it off yet to look, should probably do that this weekend and just change it out if it looks bad.

I also will be changing the fuel filter.

I do have one other theory, I think the brake booster may be leaking (very very minor and I've seen what looks like fluid, but I'll have to really get in there and double check), because I do have to add fluid every few months, so is it possible that could be the source of the issue, I'm pretty sure the booster has to do with the vacuum system as well with the lines running to it?
Test it with the propane wand technique. You probably have leaking upper/lower intake manifold gaskets, since the banks are a little bit different. But it could be a combination of an upstream (intake plenum or pre throttle leak) and a lower manifold gasket on bank 2. Bad booster is unlikely the reason why you're losing brake fluid, I'd check your rear wheel cylinders for that one.
 
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