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1999 ford taurus 3.0l 4v is throwing a p0171 code. (not ansered elseware)
1999 Ford Taurus

1999 ford Taurus 3.0L 4V is throwing a P0171 code. (not ansered elseware)

(1999 Ford Taurus)
Hi Everyone…
My mom’s 1999 ford Taurus 3.0L 4V is throwing a P0171 code.
Lots of info online about that but I have seen nothing regarding my below question.

So, I am wondering…

Of all the different things that can cause this, does the fact that when you first start the car it surges to about 1500 to 2000 RPM for about 10 to 15 seconds then idles down and runs like crap tend to lead you guys in a certain direction? (not sure about warm or cold startup)

Any ideas about this? Or… if you were working on this car, in what order of possible causes would you begin to check for the issue?

Thank you,
John

PS - A bit of smoke coming out from in-between firewall and back of engine. Smells like burning oil but I checked oil level and it was full. My mom is 85 and rarely checks anything or has any kind of maintenance done.
What seems to make the problem better or worse? ?
How long have you had this problem? 3 days
Tags: my mom s 1999 ford tauru, ford, taurus
2 answers & 6 comments
Popular Answer
on February 11, 2019
Very common for PCV valve and it’s vacuum circuits to fail - that’s the area I’d concentrate on to start with.

Check to see if system goes into closed loop and stays there as it should.
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on February 11, 2019

PCV valve ‘rubber’ vacuum connectors tend to get mushy over time and leak vacuum - feeling of these rubber components is good way to determine rigidity - visual inspection can be difficult due to location.
on February 11, 2019
My only challenge to this thought is that we don't have a P0174 along with the P0171. So, I'm looking at things that affect only one bank. Certainly, check everything is the suggestion!
on February 11, 2019

Due to the configuration - bank 1 is more susceptible to vacuum leak at PCV valve circuit.


NOTE: It is highly recommended to purchase Motorcraft replacement parts - especially the PCV valve - aftermarket valves incorporate incorrect spring tension .. Rough / rolling idle - system going open loop after engine has warmed are all telltale symptoms that PCV valve or it’s circuit have deteriorated.
on February 11, 2019

I will also add this is a rather difficult repair for the DIYer to undertake - professional *hands-on* assistance is likely to be required.

Certainly no one can positively identify the actual failure here online - these are only suggestions based on know failures and the relevant repair.
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on February 11, 2019
Very common for PCV valve and it’s vacuum circuits to fail - that’s the area I’d concentrate on to start with.

Check to see if system goes into closed loop and stays there as it should.
Sign in to reply
on February 11, 2019

PCV valve ‘rubber’ vacuum connectors tend to get mushy over time and leak vacuum - feeling of these rubber components is good way to determine rigidity - visual inspection can be difficult due to location.
on February 11, 2019
My only challenge to this thought is that we don't have a P0174 along with the P0171. So, I'm looking at things that affect only one bank. Certainly, check everything is the suggestion!
on February 11, 2019

Due to the configuration - bank 1 is more susceptible to vacuum leak at PCV valve circuit.


NOTE: It is highly recommended to purchase Motorcraft replacement parts - especially the PCV valve - aftermarket valves incorporate incorrect spring tension .. Rough / rolling idle - system going open loop after engine has warmed are all telltale symptoms that PCV valve or it’s circuit have deteriorated.
on February 11, 2019

I will also add this is a rather difficult repair for the DIYer to undertake - professional *hands-on* assistance is likely to be required.

Certainly no one can positively identify the actual failure here online - these are only suggestions based on know failures and the relevant repair.
on February 11, 2019
Having a trouble code for lean engine performance on only one of two banks kind of limits the concern to certain possible causes. This can be related to bank 1 heated oxygen sensor operation, among other possible causes. Do not guess at possible causes - hands on testing with a diagnostic tool that can monitor operation of components is important to carry out.

If I was working on the car, I would hook up a high quality diagnostic tool and look at fuel control, fuel trims, oxygen sensor voltage as well as several other parameters.

I would also be concerned about an engine oil or transmission fluid leak on hot exhaust components causing the smoke. This could be a fire hazard.
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on February 11, 2019
Thank you DaveJM...

Actually I have one but when my mother was here the other night, it was getting dark and I did not hook it up.

What did you mean by "fuel control"? Pump and filter?

Thank you,
John

PS - If I could just learn how to use it effectively. hehe...
on February 11, 2019
Fuel control -- meaning -- the heated oxygen sensors along with the mass air flow sensor, the BARO reading and other inputs will influence how much fuel is delivered to the engine for use.

The fuel pump and filter have no bearing on this P0171 code.

As Pushrod mentioned -- there could be other concerns as well the affect both banks -- but I would suspect an equivalent P0174 code also to be present. This changes a lot.

Honestly, it might be beyond your capabilities, no offense intended. Testing is needed on an expert level to figure this all out.

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