• Welcome Visitor! Please take a few seconds and Register for our forum. Even if you don't want to post, you can still 'Like' and react to posts.

P0171 Bank 1 System Too Lean


Milton

Member
U.S. Military - Veteran
Joined
May 2, 2011
Messages
91
Reaction score
0
Points
6
Vehicle Year
2009
Make / Model
Mazda
Engine Size
2.3L
Transmission
Manual
2009 Mazda B2300; 30,671 miles; oil changes every 6K; fuel system cleaner every 6K; original fuel filter, spark Plugs & wires. Never a lick of trouble.

Experienced a brief episode of rough idle which cleared. Then had a CEL. Scanned a P0171 with a pending P0171 & a pending P0720 (Output Shaft Speed Sensor Circuit). I erased the codes then went on a test drive. No issues during the drive but, pulled the data below afterwards.

Any advice on what to look for?

 


adsm08

Senior Master Grease Monkey
Supporting Member
Article Contributor
Ford Technician
TRS 20th Anniversary
Joined
Sep 20, 2009
Messages
34,623
Reaction score
3,613
Points
113
Location
Dillsburg PA
Vehicle Year
1987
Make / Model
Ford
Engine Type
4.0 V6
Engine Size
4.0
Transmission
Manual
2WD / 4WD
4WD
Tire Size
31X10.50X15
Replace your fuel filter and clean your MAF.

The fuel filter has a 30K service interval, it's probably not the problem, it's just due.
 

Milton

Member
U.S. Military - Veteran
Joined
May 2, 2011
Messages
91
Reaction score
0
Points
6
Vehicle Year
2009
Make / Model
Mazda
Engine Size
2.3L
Transmission
Manual
Replace your fuel filter and clean your MAF.

The fuel filter has a 30K service interval, it's probably not the problem, it's just due.
Thanks for the feedback. Scheduled for next weekend is:
- Fuel Pressure check
- Replace Fuel Filter (FF)
- Repeat Fuel Pressure Check
- Replace spark plugs
- Clean the MAF

I knew the FF was due @30K, which is why I mentioned it. I'll look up the MAF cleaning procedures and include that.

The fuel pressure checks will help set a baseline.

Is there a doc for what's normal for all that OBD data? It would be nice to know what's normal and what's not.

Thanks again ADSM08!
 

adsm08

Senior Master Grease Monkey
Supporting Member
Article Contributor
Ford Technician
TRS 20th Anniversary
Joined
Sep 20, 2009
Messages
34,623
Reaction score
3,613
Points
113
Location
Dillsburg PA
Vehicle Year
1987
Make / Model
Ford
Engine Type
4.0 V6
Engine Size
4.0
Transmission
Manual
2WD / 4WD
4WD
Tire Size
31X10.50X15
The PC/ED would have a reference value sheet. It's kinda bulky to post, I'll get it later.

Looking through the data the only things I see that look out of place are the fuel trims. The long is up to 25% after only 5 minutes, and the short is near 10%.

The oxygen sensor says it isn't lean, but that could be just because you were on the throttle.

Will your scanner do live data? The best initial check of a lean condition is to do a little math.

Take long term and short term fuel trims at hot idle and add them together (14+1= 15, 14+ -1=13, etc). Then do the same thing while holding the engine at 2500 RPM. Take the difference between the two numbers. If the total change is less than 15% you do not have an air leak.
 

Milton

Member
U.S. Military - Veteran
Joined
May 2, 2011
Messages
91
Reaction score
0
Points
6
Vehicle Year
2009
Make / Model
Mazda
Engine Size
2.3L
Transmission
Manual
ADSM08,

Thanks for your time and input. Yes, my scanner does do live data.

To clean the MAF sensor, I am using CRC MAF Cleaner and I reviewed this procedure for cleaning the MAF sensor: http://www.therangerstation.com/tech_library/CleanMAF.html
It seems like a well written procedure, but was written using a 2007 4.0L. The MAF sensor for my 2009 B2300 is different, and my question is do I just clean using all the openings on the MAF?

[EDIT NOTE: I answered my question and changed the pics to just a before and after.]

Here is the MAF Sensor from my B2300.

2009 B2300 MAF Sensor 30K miles without Cleaning

2009 B2300 MAF Sensor after Cleaning
 
Last edited:

Milton

Member
U.S. Military - Veteran
Joined
May 2, 2011
Messages
91
Reaction score
0
Points
6
Vehicle Year
2009
Make / Model
Mazda
Engine Size
2.3L
Transmission
Manual
Issue Resolved!!

ADSM08,

Thanks, your diagnosis & corrective action were spot on.
- I found a Utube video showing someone cleaning a 2009 Ranger MAF Sensor.
- I pulled the MAF sensor, used the CRC MAF cleaner to clean the MAF housing, and the wiring harness plug for the MAF sensor. I then used the remainder of the can of cleaner to clean the MAF sensor. You can see the before & after in the pics above. The internal components went from having a gray patina to being shiny clean.
- I let the MAF dry for 20 minutes & then reinstalled it.
- I cleared the computer codes and went on a test drive.

You could immediately notice a smoother, steadier idle and better engine performance. After the test drive I scanned & found no codes, pending or actual!!!!

Lesson learned: Clean the MAF sensor every oil change. Since I already inspect the air filter, cleaning the MAF will only add 15 minutes.

I will still change the fuel filter and spark plugs this weekend. 30K miles is the service interval for the fuel filter. I want to pull the plugs for inspection purposes, and as cheap as plugs are I'm not going to reinstall plugs with 30K on them.
 

Milton

Member
U.S. Military - Veteran
Joined
May 2, 2011
Messages
91
Reaction score
0
Points
6
Vehicle Year
2009
Make / Model
Mazda
Engine Size
2.3L
Transmission
Manual
Just to close out the thread

- Still no codes, pending or actual.
- Replaced the spark plugs
-- Autolite XP Finewire Iridium Spark Plug (XP104)
-- Manual says the OEM plugs are good for 100KMiles, but I would want to pull them & apply anti-seize compound before then.
- Replace the fuel filter

Thanks again to Adsm.
 

adsm08

Senior Master Grease Monkey
Supporting Member
Article Contributor
Ford Technician
TRS 20th Anniversary
Joined
Sep 20, 2009
Messages
34,623
Reaction score
3,613
Points
113
Location
Dillsburg PA
Vehicle Year
1987
Make / Model
Ford
Engine Type
4.0 V6
Engine Size
4.0
Transmission
Manual
2WD / 4WD
4WD
Tire Size
31X10.50X15
No problem man, glad you got her fixed.
 

hogvibrator

New Member
Joined
Oct 8, 2012
Messages
7
Reaction score
0
Points
1
Vehicle Year
2002
Make / Model
ford
Transmission
Manual
my 02 2.3 had the same issue.the idle air control valve was bad, i geuss u cant clean them.
 

Ragaway

New Member
Joined
Aug 10, 2015
Messages
1
Reaction score
0
Points
0
Vehicle Year
2007
Make / Model
Ranger/Mazda
Transmission
Manual
P0171 nightmare

Ok I have a 2007 b2300 same as ford ranger, I have several rangers actually... I use them as company vehicles. So my knowledge is strong of the trucks. I changed maf, both 02 sensors Etc...

I was at my wits end and after taking a careful look at the fuel injectors and shopping for possible swap out to see if that could be the issue. But the injectors looked new. I researched parts more and found that I had 2006 injectors in a 2007. That was the year something changed either in the computer and or injector. I replaced all 4 and bam! No more CEL and my LTFT unlatched from being stuck at 25.

So check and make sure you use the right injectors, and ignore what autozone or any other retail parts store tells you.


Perhaps I might save you the trouble I delt with.

Cheers
:yahoo:
 

Sponsored Ad


Sponsored Ad

Staff online

Member & Vendor Upgrades

For a small yearly donation, you can support this forum and receive a 'Supporting Member' banner, or become a 'Supporting Vendor' and promote your products here. Click the banner to find out how.

Truck of The Month


Kirby N.
March Truck of The Month

Recently Featured

Want to see your truck here? Share your photos and details in the forum.

Follow TRS On Instagram

TRS Events

25th Anniversary Sponsors

Check Out The TRS Store


Sponsored Ad


Sponsored Ad

Sponsored Ad


Amazon Deals

Top