Need code help 2001 Ford Taurus
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Postmaster
Joined: Aug 2004
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From: North of Boston MA
Need code help 2001 Ford Taurus
My coworker has a 2001 Ford Taurus that is throwing the code P0174 which is "System Too Lean, Bank 2". A mechanic told him it was an O2 Sensor but that the car has six and wasn't sure which one. So, multi-part question.
Does the car really have six O2 sensors? Which cylinders are bank 2? Is there a better description of that this code means? Where would I start to diagnose this issue?
I am trying to help him avoid getting shafted at the local garage. Even if I can narrow it down for him would be helpful.
Thanks in advance.
Ray
Does the car really have six O2 sensors? Which cylinders are bank 2? Is there a better description of that this code means? Where would I start to diagnose this issue?
I am trying to help him avoid getting shafted at the local garage. Even if I can narrow it down for him would be helpful.
Thanks in advance.
Ray
Hotshot
Joined: Aug 2002
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From: BC, Canada
It's got 4 sensors, 2 in front of the catalytic converters and 2 behind them.
Bank 2 is the one with cylinders 4,5 and 6......the bank at the front of the engine, next to the radiator.
You could try swapping both front sensors and see if the code follows the sensor.
Check carefully for vacuum leaks too. Most leaks show up better when the engine is cold. Spray Carb-Medic carb cleaner spray or something similar at the intake manifold where it attaches to the heads, at the vacuum hoses etc. If you spray and the idle changes you've found a leak.
Bank 2 is the one with cylinders 4,5 and 6......the bank at the front of the engine, next to the radiator.
You could try swapping both front sensors and see if the code follows the sensor.
Check carefully for vacuum leaks too. Most leaks show up better when the engine is cold. Spray Carb-Medic carb cleaner spray or something similar at the intake manifold where it attaches to the heads, at the vacuum hoses etc. If you spray and the idle changes you've found a leak.
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From: North of Boston MA
Thanks a bunch. I'll probably give him a hand changing the one bad one. Thankfully it is in front where it is easy to get to from under the hood. I appreciate the response.
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Update. We changed the O2 sensor this morning and no change. At least it was an easy job - even at 3 in the morning and 15° out. I didn't have the code reader with me but the CEL is still on. Originally it was only throwing the P0174 code according to his mechanic.
Doing some more research, I am wondering about the MAF sensor or, as Racerguy mentioned, possible vacuum leaks.
My question now is, assuming the original mechanic was correct, would a bad MAF or vacuum leak cause only one bank to run lean?
I am checking codes for him tomorrow and putting a vacuum gauge on it as well but any advice would be appreciated. Any tricks and tips to diagnosing a bad MAF? Thanks.
Doing some more research, I am wondering about the MAF sensor or, as Racerguy mentioned, possible vacuum leaks.
My question now is, assuming the original mechanic was correct, would a bad MAF or vacuum leak cause only one bank to run lean?
I am checking codes for him tomorrow and putting a vacuum gauge on it as well but any advice would be appreciated. Any tricks and tips to diagnosing a bad MAF? Thanks.
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Yeah, we disconnected the battery for several hours. After work we hooked her back up and the car ran fine with no CEL. But, by the time he got back home it was acting up again.
In an attempt at being brief, I neglected to mention that the car runs great cold. There is no hesitation, sputtering, smoking, nothing. The engine is smooth as glass until it warms up. Probably should have mentioned this - sorry.
I've got a can of carb cleaner, the code reader, a vacuum gauge and some tools in the car for tomorrow. Hopefully we can get to the bottom of this - with the help of you all.
In an attempt at being brief, I neglected to mention that the car runs great cold. There is no hesitation, sputtering, smoking, nothing. The engine is smooth as glass until it warms up. Probably should have mentioned this - sorry.
I've got a can of carb cleaner, the code reader, a vacuum gauge and some tools in the car for tomorrow. Hopefully we can get to the bottom of this - with the help of you all.
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Post Fiend
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What's the carb cleaner for? I think you will want throttle body cleaner. The carb cleaner is not good for it.
-Matt
-Matt
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From: North of Boston MA
It's for looking for vacuum leaks and it is in fact throttle body cleaner. I do know better than using carb cleaner in these new fangled engines.
I am old and still say things like "carb cleaner", "record albums" and I still "dial" telephone numbers. It's that "old dog, new trick" thing.
I am old and still say things like "carb cleaner", "record albums" and I still "dial" telephone numbers. It's that "old dog, new trick" thing.
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From: North of Boston MA
Another update - we pulled the codes this morning and got BOTH P0171 and P0174 which indicates that both banks are running lean (and we probably didn't need to change that O2 sensor).
I am leaning toward the MAF. I don't think there are vacuum leaks since the car runs to smoothly when cold but I will check that at our morning coffee break.
Anyone have any thoughts?
I am leaning toward the MAF. I don't think there are vacuum leaks since the car runs to smoothly when cold but I will check that at our morning coffee break.
Anyone have any thoughts?
Hotshot
Joined: Aug 2002
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From: BC, Canada
The hose between the air filter housing and the throttle body is tight? No hoses off anywhere?
Most vacuum leaks show up more with the engine cold.
Cleaning the MAF is quick and easy to try.
If you have access to a scan tool that will read live data take a look at https://www.ford-trucks.com/tsb/full...hp?tsb=04-17-4
Most vacuum leaks show up more with the engine cold.
Cleaning the MAF is quick and easy to try.
If you have access to a scan tool that will read live data take a look at https://www.ford-trucks.com/tsb/full...hp?tsb=04-17-4
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Postmaster
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From: North of Boston MA
Here is the latest.
No apparent vacuum leaks. Throttle body looks pretty clean (sprayed it anyway), MAF looked okay (can you tell by looking?), sprayed TB cleaner all over the manifold and any other potential leak spots and got no change in the idle which was smooth as could be with the engine cold. No CEL either....
I put the vacuum gauge on the intake manifold and it's only pulling about 18.5" but it is nice and steady. The big hose I took off (back of the manifold - supplies brake booster I think) seemed loose but my gauge was in there nice and snug.
Lunch was over before we got the car warm enough to where it would start to misbehave and throw the code but when the car is cold it runs great.
Any more thoughts before I give up?
Thanks Racerguy but I don't have access to live data......yet!
No apparent vacuum leaks. Throttle body looks pretty clean (sprayed it anyway), MAF looked okay (can you tell by looking?), sprayed TB cleaner all over the manifold and any other potential leak spots and got no change in the idle which was smooth as could be with the engine cold. No CEL either....
I put the vacuum gauge on the intake manifold and it's only pulling about 18.5" but it is nice and steady. The big hose I took off (back of the manifold - supplies brake booster I think) seemed loose but my gauge was in there nice and snug.
Lunch was over before we got the car warm enough to where it would start to misbehave and throw the code but when the car is cold it runs great.
Any more thoughts before I give up?
Thanks Racerguy but I don't have access to live data......yet!
Hotshot
Joined: Aug 2002
Posts: 12,679
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From: BC, Canada
About the only thing you can tell by looking at the MAF is whether or not it needs cleaning. Take a look at the little filament looking pieces inside and see if there is any fuzzy buildup on them. If there is spray it off with electrical contact cleaner or something like that. Don't touch them...they break easily.
18.5" of vacuum should be good.
Do you have access to a fuel pressure gauge? Checking the pressure at the fuel rail would be a good idea too.
18.5" of vacuum should be good.
Do you have access to a fuel pressure gauge? Checking the pressure at the fuel rail would be a good idea too.
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From: North of Boston MA
It's always the stupid little things.....
As it turned out, or so we believe so far, the stupid little rubber elbow for the PCV valve had a leak in it. Put a piece of tape over it and so far no problems with it. We looked and looked for vacuum leaks yesterday and never found any but he found the leak last night after the engine was nice and hot. With the engine cold to warm we couldn't find a thing. Who knows, maybe as the engine got hot that rubber elbow expanded enough to leak or something. Aggravating.
He drove it to and from work today and it ran great for him. He reset the computer so I'll check codes tomorrow but it's looking good. I'm rechecking the vacuum too just for kicks - I want to see what it is without leaks.
Thanks for all the help on this. I learned a lot from ya'll.....and I'm getting lunch from my coworker but he really owes it to you folks.
As it turned out, or so we believe so far, the stupid little rubber elbow for the PCV valve had a leak in it. Put a piece of tape over it and so far no problems with it. We looked and looked for vacuum leaks yesterday and never found any but he found the leak last night after the engine was nice and hot. With the engine cold to warm we couldn't find a thing. Who knows, maybe as the engine got hot that rubber elbow expanded enough to leak or something. Aggravating.
He drove it to and from work today and it ran great for him. He reset the computer so I'll check codes tomorrow but it's looking good. I'm rechecking the vacuum too just for kicks - I want to see what it is without leaks.
Thanks for all the help on this. I learned a lot from ya'll.....and I'm getting lunch from my coworker but he really owes it to you folks.