2001 Mazda B3000 Engine missed fire and coded P0171

Tiny
VICAUTO2
  • MEMBER
  • 2001 MAZDA B3000
Engine Performance problem
2001 Mazda b3000 6 cyl Two Wheel Drive Manual

Hi, I have a pick up truck Madaz 2001, manual, 81,000 miles, I have problem engines missed fire cylynder # 1 and # 3, but did not showed code for missed fire, Engine showed code P0171 ( Cilynder #1 Bank 1 too lean ).
Sofar I have replaced new coil pack, new spark plug and wire, and new gas filter, also serviced fuel injection, I checked each fuel injection with long scop, I heard it pump and with noid light, it flashed. I also checked spark to spark plus. It 've got spark strongly. Checked all vacuum hoeses did not find any leak, and spay caburator cleaner around intake manifold not any leak, either.
I drove the truck to local auto zone, scan trouble code.
code P0171
Lean Air/ fuel ratio Bank 1
(cylinder #1 denotes Bank 1)
probale cause.
1 Low fuel pressure
2 Large vacuum leak
3Dirty/defective MAF sensor
4Engine mechanical condition.
Please, some one give me some advice, What 's problem my truck and How to fix it? Thank you
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Saturday, January 16th, 2010 AT 6:01 PM

11 Replies

Tiny
RASMATAZ
  • MEMBER
Hi vicauto2, Welcome to 2carpros and TY for the donation.

P0171 indicates lean condition-could be one of the following below:

* 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)
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Saturday, January 16th, 2010 AT 6:06 PM
Tiny
VICAUTO2
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Hi, Sofar, I haven't got any luclk yet, I 've tried whole sunday went back and fowar to buy compressure test and fuel injection test, It took a few trip to get a right adaptor for 2 major test , but did not fix right problem,
I tested cilynder#1 = 150 psi
fuel pressure = 60 psi w/o engine run, 67 psi with engine run.
I cleaned MAF sensor with rubber alcohol.
And double check ignition spark cilynder # is OK.
When started engine is still same proplem, running only 4 cinlyder, cilynder #1 and # 3 misses fire, But on dasboard did not show and trouble code. I hooked up OBDII could not scan any code.
Sofar I haven't find any vacuum leak, I spayed 1 can cab cleaner around EGR valve and round lower part of intake manifold to see engine state, but not thing.
Any helps will be apreciated.
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Sunday, January 17th, 2010 AT 6:08 PM
Tiny
RASMATAZ
  • MEMBER
Engine misfires can also be caused by worn or fouled spark plugs, a weak spark (weak coil, bad spark plug wire), loss of compression, vacuum leaks, anything that causes an unusually lean fuel mixture (lean misfire), an EGR valve that is stuck open, dirty fuel injectors, low fuel pressure, or even bad fuel.
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Sunday, January 17th, 2010 AT 6:49 PM
Tiny
VICAUTO2
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Hi ! Thank you for quick responding. Please, some one tell me Why engine missed fire, But did not show and code? I could not scan any codes.
Any helps will be apreciated.
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Monday, January 18th, 2010 AT 3:24 AM
Tiny
VICAUTO2
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Hi, I removed intakemanifold again, and tracing all the hoses around it, and around the engine, But could not find any leak, checked PCV ok, It 's rattle, no stuck.
I've tested and replaced new Oxygen sensor on Bank 1, and new upper intake manifold gasket.
It's still same problem, cylinder 1 and 3 misfired,
Do you know any electrical relate to the problem?
Thank you?
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Monday, January 25th, 2010 AT 5:06 AM
Tiny
RASMATAZ
  • MEMBER
Check no.1/3 sparkplug/compression/injector
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Monday, January 25th, 2010 AT 3:12 PM
Tiny
VICAUTO2
  • MEMBER
Hi, Please, some one tell me where was the vacuum pump"s motor location on my Madaz V6 engine 3.0? Or Does it have vacuum pump's motor?
I recently hooked up vacuum gage to intake manifold port to check how my engine vacuum. It was steady but low side about 11 in hg, It should be healthy at 15 to 20 in hg at idle speed.
The problem could be internal vacuum leaking, I could find any external leaking, the upper intake manifold gasket has been replaced new, I may change lower intake gasket, Just working around may or may not right.
Once more time, Please tell me where is my Madaz V6 engine vacuum mortor? Thank you.
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Tuesday, February 2nd, 2010 AT 6:58 PM
Tiny
VICAUTO2
  • MEMBER
Hi, I recently replaced IAC solonoild, PCV valve, and EGR valve, But The engine is still rough, The Engine vauum is still low, it's only 11 Hg, It should be 15 to 20 Hg for healthy engine.
All the part have been replaced, the only thing is intake manifold runer. That the thing Engine take out side air create vauum . But engine did not show any diagnostic code, as P0171, 0r P1512 as Intake manifold runner control (IMRC ) malfuntion ( bank 1 stuck open)
Is there any body know about Intake manifold runner, please, tell me, Thank you
No give up, be pation, keep working around.
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Thursday, February 11th, 2010 AT 4:04 AM
Tiny
RASMATAZ
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Engine misfiring can be caused by worn or fouled spark plugs, a weak spark (weak coil, bad spark plug wire), loss of compression, vacuum leaks, anything that causes an unusually lean fuel mixture (lean misfire), an EGR valve that is stuck open, dirty fuel injectors, low fuel pressure, or even bad fuel.
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Thursday, February 11th, 2010 AT 5:34 AM
Tiny
VICAUTO2
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HI, It would be nicer to hear different opinion than the same general technic apply for any thing. Thank you any way.
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Thursday, February 11th, 2010 AT 6:01 PM
Tiny
RASMATAZ
  • MEMBER
You have 2 misfiring cylinders you need to check the sparkplug, compression and injectors on those cylinders

Misfires can be caused by compression, fuel and ignition problems am sorry this is not an easy fix-proper diagnostics has to be performed, misfires can be a nightmare to remember. You need to follow up with what I've suggested earlier
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Thursday, February 11th, 2010 AT 6:56 PM

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