CHECK ENGINE LIGHT - CODES P0170 & P0174

  • Tiny
  • TxDC
  • Ford Explorer

I have been chasing a persistant CE issue for 6 months. If anyone knows a fix that works PLEASE help.
Ford Explorer Sport Trak 2wd 2001 4.0L SOHC V6 140,000 miles
What I've tried so far in sequence of repair:
-all 3 O2 sensors
-Fuel Filter
-Sensor on Right Valve Cover[2 vac lines]
-EGR Valve
-proffessional Power Clean Injectors
-PCV valve assembly [w/3 VAC hoses]
-Replaced both O-ring sets in Intake/throttle Body
-MAF Sensor

Until I replaced the MAF sensor the Check Engine light would come back on in approx 50-100miles after replacing MAF Sensor it comes back after erase in about 15-40 miles.

Wednesday, January 31st, 2007 AT 6:24 AM

8 Answers

  • Tiny
  • knightriderkitt2000
  • Member

Check fuel pressure, also check for any vacuum leaks, both codes are more than likely being set off by the same problem.

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Wednesday, January 31st, 2007 AT 7:33 AM
  • Tiny
  • rasmataz
  • Member

Check the TPS sensor sometimes this sensor will give the PCM a curve ball and cause a CEL problem with MAF.

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Wednesday, January 31st, 2007 AT 3:56 PM
  • Tiny
  • Service Writer
  • Expert
  • 9,254 posts

Lets start with basics-what codes do you have now showing? An independent shop is capable of taking care of this, (all depends on what quality of techs the shop or dealer hired and the ethics they follow).

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Wednesday, January 31st, 2007 AT 5:36 PM
  • Tiny
  • TaurusWheel
  • Member

I'd recommend taking it to the Ford dealer and having them run pinpoint diagnostics on the codes you have now. The codes you posted, p0170 I can't find, and p0174 which relates to bank 2 #1 o2 sensor, it's running lean and can't further correct itself for some reason. Like above replies, simple things first, make sure nothing is loose or broken, unhooked. Vacuum hoses and such. Don't go replacing parts needlessly, it costs too much and it still ain't fixed. I don't think the dealer is way out of line with cost of pinpoint testing, unless you've got scan tools, manuals, breakout boxes and such to do it yourself.

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Wednesday, January 31st, 2007 AT 9:42 PM
  • Tiny
  • Service Writer
  • Expert
  • 9,254 posts

Sorry I'm a retard, didn't see you posted codes : oops: Your note on the MAF sensor may be key, as there was a change. I have found aftermarket MAFs are high in defect rate. I would suggest the OEM one on this. This buggers are common on this animal.

No vacuum leaks I hope, especially after the maf?

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Thursday, February 1st, 2007 AT 5:33 AM
  • Tiny
  • TxDC
  • Member

All of the Sensors were FORD parts not AM.
No Vac Leaks - the PCV assy includes new hoses
We sprayed down the entire intake & Vac lines, while running with Berrymans and no RPM change

TPS & Idle sensors are orignal

What should the Fuel Rail Pressure be?

Any Idea how much a 'Pinpoint Diag Test' costs?

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Thursday, February 1st, 2007 AT 6:15 AM
  • Tiny
  • rasmataz
  • Member

First On Race Day or Found On the Road Dead

Better check the fuel pressure to rule out clogged injectors, pressure regulator, failing F/pump

Overall something is leaning the mixture. Double check the EGR

BTW how about them plugs and wires have they been changed or what? Also can be a bad gas with water or too much alcohol in it.

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Thursday, February 1st, 2007 AT 6:19 AM
  • Tiny
  • rasmataz
  • Member

Cannot remember it all: A lean fuel condition can be caused by: * Low fuel pressure due to a weak pump or leaky fuel pressure regulator. (Use a fuel pressure gauge to check fuel pressure at idle)

* Dirty fuel injectors. (Try cleaning the injectors)

* Vacuum leaks at the intake manifold, vacuum hose connections or throttle body. (Use a vacuum gauge to check for low intake vacuum)

* Leaky EGR valve. (Check operation of EGR valve)

* Leaky PCV Valve or hose. (Check valve and hose connections)

* Dirty or defective Mass Airflow Sensor (MAF). (Try cleaning the MAF sensor wires or filament with aerosol electronics cleaner. Do NOT use anything else to clean the sensor, and do not touch the sensor wires)

The O2 sensors are they OEM

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Thursday, February 1st, 2007 AT 7:50 AM

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