From: Ray O on
A friend recently contacted me to ask about a check engine light on their
2000 Windstar with 105,000 miles and to ask why the engine idles poorly and
acts like it is going to stall unless the transmission is in neutral and the
driver blips the throttle. Service history - replaced fuel pump 3 years ago
for a no-start condition; replaced spark plugs at 60 K miles with cheap
aftermarket spark plugs; oil changes once or twice a year at 5,000 mile
intervals; uses about 1 quart of oil per 1,000 miles, often run 2 or 3
quarts low on oil because oil gets checked

I plugged in my handy dandy OBD II scanner and found P0171 - system too lean
Bank 1 and P0174 - system too lean Bank 2. I know the cause, and for this
exercise, I ask that the pros like aaracuda and claire@... NOT respond with
the correct answer because I'm curious to see what the shade tree folks here
come up with. Of course, the pros are welcome to respond with an
explanation why a particular answer is correct or incorrect, IOW, serve as a
teacher and not as a student.

Here is the quiz part: What is the likely cause of P0171 and P0174? Like
school quizzes, respondents have to explain why their answer is a likely
cause.

--

Ray O
(correct punctuation to reply)


From: Hachiroku ハチロク on
On Mon, 18 Jan 2010 14:48:53 -0600, Ray O wrote:

> A friend recently contacted me to ask about a check engine light on their
> 2000 Windstar with 105,000 miles and to ask why the engine idles poorly
> and acts like it is going to stall unless the transmission is in neutral
> and the driver blips the throttle. Service history - replaced fuel pump 3
> years ago for a no-start condition; replaced spark plugs at 60 K miles
> with cheap aftermarket spark plugs; oil changes once or twice a year at
> 5,000 mile intervals; uses about 1 quart of oil per 1,000 miles, often run
> 2 or 3 quarts low on oil because oil gets checked
>
> I plugged in my handy dandy OBD II scanner and found P0171 - system too
> lean Bank 1 and P0174 - system too lean Bank 2. I know the cause, and for
> this exercise, I ask that the pros like aaracuda and claire@... NOT
> respond with the correct answer because I'm curious to see what the shade
> tree folks here come up with. Of course, the pros are welcome to respond
> with an explanation why a particular answer is correct or incorrect, IOW,
> serve as a teacher and not as a student.
>
> Here is the quiz part: What is the likely cause of P0171 and P0174? Like
> school quizzes, respondents have to explain why their answer is a likely
> cause.

It's a Ford 3.8L engine. Is the intake runner melting?

I would look for the easy stuff first, like a clogged fuel filter, air
filter, and an intake (MAF?) stuck open. Also would check the injectors as
best as I could (screwdriver to the ear, click, click, click...)

Could also be an air intake hose that has a hole in it somewhere.

From: ED on
Check for vacuum or air leaks in Intake Manifold area.
Clean MAF
Check and R/R if necessary both Oxygen Sensors.
This engine has a known problem of bad O-rings in the intake plenum,


"Ray O" <rokigawa(a)NOSPAMtristarassociates.com> wrote in message
news:hj2hlm$bhc$1(a)news.eternal-september.org...
>A friend recently contacted me to ask about a check engine light on their
>2000 Windstar with 105,000 miles and to ask why the engine idles poorly and
>acts like it is going to stall unless the transmission is in neutral and
>the driver blips the throttle. Service history - replaced fuel pump 3
>years ago for a no-start condition; replaced spark plugs at 60 K miles with
>cheap aftermarket spark plugs; oil changes once or twice a year at 5,000
>mile intervals; uses about 1 quart of oil per 1,000 miles, often run 2 or 3
>quarts low on oil because oil gets checked
>
> I plugged in my handy dandy OBD II scanner and found P0171 - system too
> lean Bank 1 and P0174 - system too lean Bank 2. I know the cause, and for
> this exercise, I ask that the pros like aaracuda and claire@... NOT
> respond with the correct answer because I'm curious to see what the shade
> tree folks here come up with. Of course, the pros are welcome to respond
> with an explanation why a particular answer is correct or incorrect, IOW,
> serve as a teacher and not as a student.
>
> Here is the quiz part: What is the likely cause of P0171 and P0174? Like
> school quizzes, respondents have to explain why their answer is a likely
> cause.
>
> --
>
> Ray O
> (correct punctuation to reply)
>


From: aarcuda69062 on
In article <hj2hlm$bhc$1(a)news.eternal-september.org>,
"Ray O" <rokigawa(a)NOSPAMtristarassociates.com> wrote:

> A friend recently contacted me to ask about a check engine light on their
> 2000 Windstar with 105,000 miles and to ask why the engine idles poorly and
> acts like it is going to stall unless the transmission is in neutral and the
> driver blips the throttle. Service history - replaced fuel pump 3 years ago
> for a no-start condition; replaced spark plugs at 60 K miles with cheap
> aftermarket spark plugs; oil changes once or twice a year at 5,000 mile
> intervals; uses about 1 quart of oil per 1,000 miles, often run 2 or 3
> quarts low on oil because oil gets checked
>
> I plugged in my handy dandy OBD II scanner and found P0171 - system too lean
> Bank 1 and P0174 - system too lean Bank 2. I know the cause, and for this
> exercise, I ask that the pros like aaracuda and claire@... NOT respond with
> the correct answer because I'm curious to see what the shade tree folks here
> come up with. Of course, the pros are welcome to respond with an
> explanation why a particular answer is correct or incorrect, IOW, serve as a
> teacher and not as a student.
>
> Here is the quiz part: What is the likely cause of P0171 and P0174? Like
> school quizzes, respondents have to explain why their answer is a likely
> cause.

Awww Ray....!
From: SMS on
Ray O wrote:

> Here is the quiz part: What is the likely cause of P0171 and P0174? Like
> school quizzes, respondents have to explain why their answer is a likely
> cause.

A problem with the Mass Airflow Sensor. Either the sensor is working but
there's a vacuum leak, or the sensor is dirty.