MAF reading

[huntermw67]

Hi all,

New to this forum and my '01 Explorer Sport. I'm currently getting a CEL with codes P0171 and P0174. I know the code's for lean readings at the O2 sensors. My question is: Can anyone with a scantool tell me what the MAF sensor is reading at idle?? Mine is reading around 1.7 lbs/min currently. I think I may have a bad MAF sensor, however, I haven't been able to find out what the 4.0L engine should read at idle. I'm looking for a ball park figure of what the air flow should be, as it appears to be reading very high for a 6-cyl engine. Also, ftr, I haven't been able to locate anything that might be a vacuum leak.

Thanks,

Mike

 

[JusTheUsual]

Check your fuel pressure then go from there. It seems like its running lean or too much air. Usually im pretty sure but not 100percent sure, most of the time it would run rich with a bad maf. Yours is running lean. Check your fuel pressure then go from there. Plenum orings also are common causes to those codes in these vehicles

 

[fritz24]

You have 13g/s which almost twice or thrice as much as normal reading. I got 4.0L and im getting 4 (+/-5) at idle after cold start and when driven for 30 mins(hot idle) it is reading 4.5 to 5.5 or sometimes it will reach 6+ depending on outside ambient temp. If your scan tool can display voltage of your maf you can use this reference PID values.
@ KOEO = 0 volt
hot idle = 0.7 - 0.9
30 mph= 1.2 -1.8
55mph= 1.6- 2.1
try cleaning it first with contact cleaner or maf cleaner and check the wires. Make sure your maf sensor has cooled down when cleaning.
P0171 174 can be caused by
fuel sysyem
air induction system
exhaust system
egr system

 

[swshawaii]

P0171 & P0174 4.0L SOHC's Sport/Sport Trac
http://www.explorerforum.com/forums/showthread.php?t=314670

Lean condition procedure
http://www.explorerforum.com/forums/showthread.php?p=2364255

2000StreetRod's Helpful thread list
http://www.explorerforum.com/forums/showthread.php?p=2349038

 

[huntermw67]

Thanks for the info guys. I replaced the MAF sensor yesterday and the air flow readings immediately dropped to .5-.6 lbs/min at idle. The short term fuel trims are still really high(like +20% at idle), but increasing the rpms brings them right down to where they should be, leading me to believe I probably do have a vacuum leak somewhere. So, it appears that I have multiple issues going on at the moment. Looks like it's time to break out the carb cleaner next time I have a chance to work on it.

 

[2000StreetRod]

smoke test

Control of idle speed by the PCM and the IAC valve has a short response time making it very difficult to accurately detect intake manifold leaks using aerosols. In my opinion, the only reliable method for locating intake leaks is a smoke test.

 

[fritz24]

Did you reset the PCM when you replaced the MAF? You can get accurate reading of STFT when the engine at operating temperature. On start up youll definitely get a high value on STFT. The long term fuel trim should indicate that you have a lean condition since the PID's on this sensor is a stored data and the value is constant not like the short term fuel trim pids that its value is shifting to rich and lean.

 

[huntermw67]

Fritz,

I did not reset the pcm. Currently I only have one key for the truck and no remote entry keyfobs. I was leery of disconnecting the battery, due to the alarm system. This being my first Ford, I wasn't sure if I would be able to shut the alarm off after reconnecting the battery without the remote.

Mike

 

[2000StreetRod]

additional keys

I suggest that you purchase two additional PATS keys before you lose your only key and have to get your vehicle towed to the dealer or a PATS qualified locksmith in order to drive it.

Disconnecting the battery will not affect PATS but I don't know about your alarm system. At some point you'll have to replace the battery or clean the battery terminals. Is your alarm an aftermarket system?

 

[huntermw67]

I think it's just the PATS system, and I recently let it sit for about 10 days and had to put my charger on the battery to start it. Looks like a new battery's also in my future.

 

[RadioAD5GB]

Hi all,

New to this forum and my '01 Explorer Sport. I'm currently getting a CEL with codes P0171 and P0174. I know the code's for lean readings at the O2 sensors. My question is: Can anyone with a scantool tell me what the MAF sensor is reading at idle?? Mine is reading around 1.7 lbs/min currently. I think I may have a bad MAF sensor, however, I haven't been able to find out what the 4.0L engine should read at idle. I'm looking for a ball park figure of what the air flow should be, as it appears to be reading very high for a 6-cyl engine. Also, ftr, I haven't been able to locate anything that might be a vacuum leak.

Thanks,

Mike

I'm having similar issues with my '05 XLT. Constant P0171; P0174 codes. Terrible idle; stalls frequently. Awful fuel mileage. I just ordered the upgrade for my "Auto Enginuity" software. I haven't had this thing that long and it's been a long time since my "Ford mechanic' days so I'm trying to find out what the expected ranges of all these pain points are. Keep in mind that any vacuum leaks or air that enters the induction system downstream of the MAF sensor is un-metered. The ECU doesn't know about it but keeps trying to correct for an excessively lean condition. The O2 sensors keep saying "LEAN LEAN LEAN". It's greater that what the ECU can compensate for so it throws DTCs at us. I'm fairly certain that's the problem with mine anyway, just can't find it yet. I run between 32 and 45 PSI of fuel pressure so unless every injector is toast, there;s got to be a horrible vacuum leak somewhere. Scan tool upgrade and shop manual are on the way. I'll find it. I haven't been beaten yet LOL....

 

[410Fortune]

Fuel
Pressure spec for a 2005 is 64 psi plus or minus

Sounds like you have a weak fuel pump at 40
Psi your injectors are not spraying the fuel properly

The sohc engine is known for leaky intake o rings which can cause a lean condition on both banks as well

 

[RadioAD5GB]

Fuel
Pressure spec for a 2005 is 64 psi plus or minus

Sounds like you have a weak fuel pump at 40
Psi your injectors are not spraying the fuel properly

The sohc engine is known for leaky intake o rings which can cause a lean condition on both banks as well

Wow! Okay then. Intake o-rings are new; replaced the line sensor and had to pull the upper intake to do so.

Google returns 30-40psi as "spec" . I guess I'll find out for sure and for certain once the (apparently secret) factory specs arrive in the form of a genuine Ford service manual. I'm so sick of this junk.......

I bought a 2006 VW Jetta TDi back in 2006 because I knew I would be spending a lot of my time driving in the course of my work as a software engineer/developer. At that time, diesel fuel at the pump was the cheapest and the TDi could easily scrape the 46 mpg mark. Times have changed. Diesel is the MOST EXPENSIVE choice at the pump and my Jetta was totaled in a T-Bone by a drunk driver.

The '05 Explorer was all I could afford out of the insurance settlement and while it's still pretty, it really sucks trying to obtain actual "REAL" design operating parameters - even something as simple as fuel pressure,

F* Google

 

[410Fortune]

Okay so info is iffy for this model and I think I know why. When you lookup fuel pressure spec for a 05 results vary

This maybe because in 2005 the computer now monitors fuel pressure and adjusts it any drive. 05’isnthe first year that fords started doing this (that I’m aware of) 05’wasnthe first year of the fuel pump driver module and also the first year of the fuel pressure sensor for the pcm

So the computer is monitoring fuel psi and adjusting it
So I believe while spec is 64 psi for the returnless fuel rail systems the computer will set rail pressure around 42 psi while driving at at idle. Demand goes up fuel pressure goes up. The pcm does this by modulating the power to the fuel pump

Your 171 and 174 codes are classic lean condition due to either
Un metered air
Or
Low fuel psi

So since you have done intake o rings we have to rule out fuel psi as the suspect next step would be a smoke test to find the gross intake leak

I drive a 97 f350 7.3 turbo diesel, a 01 excursion 7.3 diesel and a couple of 5.0 explorers… you don’t have to tell me about diesel prices… my shop and house is off grid and when there is no sunshine we run on red diesel, the whole house and shop
Is powered by turbo diesel military genset… diesel should be the cheapest fuel not the most expensive

 

[RadioAD5GB]

Okay so info is iffy for this model and I think I know why. When you lookup fuel pressure spec for a 05 results vary

This maybe because in 2005 the computer now monitors fuel pressure and adjusts it any drive. 05’isnthe first year that fords started doing this (that I’m aware of) 05’wasnthe first year of the fuel pump driver module and also the first year of the fuel pressure sensor for the pcm

So the computer is monitoring fuel psi and adjusting it
So I believe while spec is 64 psi for the returnless fuel rail systems the computer will set rail pressure around 42 psi while driving at at idle. Demand goes up fuel pressure goes up. The pcm does this by modulating the power to the fuel pump

Your 171 and 174 codes are classic lean condition due to either
Un metered air
Or
Low fuel psi

So since you have done intake o rings we have to rule out fuel psi as the suspect next step would be a smoke test to find the gross intake leak

I drive a 97 f350 7.3 turbo diesel, a 01 excursion 7.3 diesel and a couple of 5.0 explorers… you don’t have to tell me about diesel prices… my shop and house is off grid and when there is no sunshine we run on red diesel, the whole house and shop
Is powered by turbo diesel military genset… diesel should be the cheapest fuel not the most expensive

I'm no stranger to OBDII junk. I was a Ford line tech for almost 13 years. This is just not adding up - lacking "DESIGN SPECIFICATIONS"

I HATE Google for this **** and I HATE Ford, for withholding the diagnostic details.

I'm going to start driving my (highly tuned ) '06 F-250 FX4 6.0 because

1: She lights, she runs
2: She still gets 17 MPg
3: She runs the 1/4 mile traps @ low 13's
4: ?????