Help with codes

[Magicape]

Hi, Folks,

I've gotten P0171 twice and both P0171 and P0174 together once. This is lean mixture, left or right bank. Each time it's been at start-up and the light stays off when I turn it off. Now and then the car is a bit hard starting and mostley the idle is rough. Any suggestions or should I not worry and ignor the codes?

Hank

[Zack]

Whats the mileage?

[magindat]

Check around and make sure all vacuum lines and pcv valves are attached an functioning properly.

Make sure your idle control line (under the throttle body) is attached and not leaking.

Make sure your intake isn't leaking.

I'd lean (pun intended) toward the IAC line being compromised. That'll make it run like ***** at idle, but smooth out with revs. Would also be sucking unmetered air and could throw the lean code.

[Magicape]

Mileage is 84K. New fuel filter and plugs at 50K. Lidio tune and K&N intake.

What is an IAC line?

[magindat]

Mileage is 84K. New fuel filter and plugs at 50K. Lidio tune and K&N intake.

What is an IAC line?

It bypasses the throttle body plate so the car has enough air to idle when the plates are shut.

[Magicape]

Oh, Idle Air Control line--

[superford3]

id say intake is leaking

[whd507]

IAC was my first guess. I get customers with 171/174 codes every day.

[JMan]

Do you have a way to read PCM data. Find the BAROmeter parameter and let us know what it reads. Should be 159Hz +/- 3Hz at sea level. I don't have a clue as to your altitude but can find a corelation chart if necessary. If the BARO reading is down below ~ 152Hz, it is leaning your mix out for the thin air at high altitude. This is often caused by oiled air filters! Check it out.

Best luck,

J

[Magicape]

No, all I have is an SCT which reads codes, but if the setting is wrong the codes would have been coming up since I've had the car, not just recently. I've got to check things out more over the weekend. Thanks to all.

[Jerry]

Do you have a way to read PCM data. Find the BAROmeter parameter and let us know what it reads. Should be 159Hz +/- 3Hz at sea level. I don't have a clue as to your altitude but can find a corelation chart if necessary. If the BARO reading is down below ~ 152Hz, it is leaning your mix out for the thin air at high altitude. This is often caused by oiled air filters! Check it out.

Best luck,

J

You are part right and part wrong.

First off the baro sensor in the Marauder is not really a baro sensor, it's part of the EGR system. It's output is NOT frequency, it's a voltage. Also, a low baro reading will NOT in any way, shape or form lean the engine out. This is a mass air system, it measures the mass of the air going into the engine and puts in the correct amount of fuel. No where in the calculations is BP involved in the amount of fuel delivered.

Now, he has a K&N air filter. I wish K&N would go out of business or change their marketing. The oil on the air filter migrates off the filter and deposits itself on the hot wire of the MAF. This then insulates the MAF wires and shifts the fuel control lean. I would start by cleaning the MAF wires then pull the battery cable off so that it clears all the adaptive...

j

[JMan]

You are part right and part wrong.

First off the baro sensor in the Marauder is not really a baro sensor, it's part of the EGR system. It's output is NOT frequency, it's a voltage. Also, a low baro reading will NOT in any way, shape or form lean the engine out. This is a mass air system, it measures the mass of the air going into the engine and puts in the correct amount of fuel. No where in the calculations is BP involved in the amount of fuel delivered.

Now, he has a K&N air filter. I wish K&N would go out of business or change their marketing. The oil on the air filter migrates off the filter and deposits itself on the hot wire of the MAF. This then insulates the MAF wires and shifts the fuel control lean. I would start by cleaning the MAF wires then pull the battery cable off so that it clears all the adaptive...

j

Jerry,
Not wanting to argue points with a Ford engineer, but I was under the impression that the absolute pressure based EGR sensor was an addition in the '05 model year. My cars ('96, '03 & '04) all show a BARO PID read in Hertz. My impression here was, that the reading was an inferred value calculation of the air density using the MAF/TPS/IAT input. Hence my reference to it in the previous post. I agree fully with the K&N oil / hot wire soiling. Anything that skewes the Air Mass reading changes the fuel metering. I believed that the BARO reading would be the indicator of this condition. Please, set me straight!

Thank you for your input on this thread - it is great to have you aboard!

J

[thePunisher]

yes in the marauder, 03 anyway, the esm or egr system module does not incorporate the baro. baro is still inferred by the maf. not every eec system using the esm uses it for baro. although most everything newer does......id say in this case the maf sensor is no good. it is definitely not an iac concern. iac in no way will cause a lean condidtion. and a false baro reading will cause a lean condition at part throttle. if the baro reading is 137 and were at sea level the pcm thinks we are a mile high and cant adjust the fuel trims enough to compensate...therefore creating a lean condition....

[Drock96Marquis]

Clean the MAF sensor element(s) with a non-residue contact cleaner. To do so just unclip the airbox uppler lid, and tilt it upwards (disconnect MAF harness if needed)
Spray the 'wires' through the square cutout in sampling tube.
Let dry for a few minutes, then reassemble. Clear the KAM if desired by disconnecting the battery ground for ~5+ minutes.

Look for vacuum leaks. Make sure the IAC supply tube is on firmly.

[JMan]

You are part right and part wrong.

First off the baro sensor in the Marauder is not really a baro sensor, it's part of the EGR system. It's output is NOT frequency, it's a voltage. Also, a low baro reading will NOT in any way, shape or form lean the engine out. This is a mass air system, it measures the mass of the air going into the engine and puts in the correct amount of fuel. No where in the calculations is BP involved in the amount of fuel delivered.

Now, he has a K&N air filter. I wish K&N would go out of business or change their marketing. The oil on the air filter migrates off the filter and deposits itself on the hot wire of the MAF. This then insulates the MAF wires and shifts the fuel control lean. I would start by cleaning the MAF wires then pull the battery cable off so that it clears all the adaptive...

j

From the Motorcraft Website:
[quote]

In the 2002.5 MY, Ford will introduce a revised DPFE system. It functions in the same manner as the
conventional DPFE system, however, the various system components have been combined into a single
component called the EGR System Module (ESM). This arrangement increases system reliability while reducing
cost. By relocating the EGR orifice from the exhaust to the intake, the downstream pressure signal measures
Manifold Absolute Pressure (MAP). The ESM will provide the PCM with a differential DPFE signal, identical to the
conventional DPFE system. The DPFE signal is obtained by electrically subtracting the MAP and P1 presure
signals and providing this signal to the DPFE input on the PCM. 2003 MY and later implementation of the ESM
system will add a separate input to the PCM for the MAP sensor signal
[and]
The ESM may provide the PCM with a separate, analog Manifold Absolute Pressure Sensor (MAP) signal. For the
2003 MY, the MAP signal has limited use within the PCM. It may be used to read BARO (key on, updated at high
load conditions while driving) or to modify requested EGR rates. Note that is the MAP pressure-sensing element
fails in the ESM fails, the DPFE signal is also affected. Therefore, this MAP test is only checking the circuit from the
MAP sensing element to the PCM.
[end quote]


Wow, only a dummy would argue points with a Ford engineer! As my dad used to say, "Use your head, boy!". Thought I should highlight my misperception first! Sorry to dig up this old thread.


Humbly,


J