Engine running lean?

There is a know problem with the O ring seal on the intake manifold tuning valve, it leaks and causes the lean codes P0171-P0174.

This guide can help fix it as well

https://www.2carpros.com/articles/repair-lean-mixture-codes-p0171-or-p0174-on-some-manufacturers


Please run down this guide and report back.

2002 Ford Taurus 103000 miles
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im having the same issue... This started with my car stalling while sitting idol. We replaced both heads, wires and such. Now getting Lean Bank, and a missfire on #5. Im thinking these issues may be caused by the extreme vacuum in the engine. When we pull off the new PCV valve or Oil cap the engine stalls.

The gasket on the intake also has slipped, and getting a very high piched scream from there at idol.

im weak when it comes to cars, and my mecanic has replaced many things. He gave me my car back totally confused, and not sure whatelse to do.

Thank you.... Ill pull it into the garage and inspect the duct work tonight.

That's a definite problem with newer cars, a lot of mechanics, good ones too, are not necessarily trained in diagnosing and repairing newer vehicles, mostly pertaining to areas of electronics, computers and such.. it's a very large cost to buy and maintain these diagnostic machines plus the continued training on all types of vehicles.. this is not a knock on any mechanic. Most are very good at the mechanical ends of vehicles.. there have been problems with pcv valves and related hoses causing lean conditions.. hoses develop pinhole leaks..

I ran a diagnostic test and got these codes P0171 mod$10 system too lean (bank 1) & p0174 mod$10 system too lean (bank 2).

What do they reallly mean? I am not mechanicaly inclined at all. Is this an easy fix? Is is expensive?

P0171/P0174 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)

* TIP: On many Fords, a P0171 and/or P0174 Lean Code may sometimes appear because of a bad Differential Pressure Sensor (DPFE). This sensor monitors EGR flow, and is located on the engine near the EGR valve. There are two hoses that connect the sensor to the tube that runs from the exhaust manifold to the EGR valve. The sensor misreads EGR flow and the computer increases EGR which has a leaning effect on the fuel mixture. The fix is to replace the DPFE sensor

Im getting the codes p0171 and p0174 which are lean bank 1 and lean bank 2 can u help. :?:

That means that both banks of cylinders are running lean... too little fuel for the amount of air being used.
1) you might have several plugged or partially plugged fuel injectors
2) your fuel pressure might be weak
3) i've seen the same check engine code in vehicles that have wide open cold air intakes that use a MAF (mass air flow) sensor housings that are not stock. It screws around with the computer's calibration.
I hope this helps some.

thanks I'll check some things out.

I have a 2001 Ford Taurus with 68,000 miles on it's 3.0 DOHC motor and about a month ago it started to get hard to start. Since then it has begun to rev to about 2,000 rpm when first started then idles badly between 500 and 800 rpm. It sputters and lurches when in drive with the brake pushed to the floor. It only does this when it is cold outside or if the motor it cold. The check engine light only recently came on and the code says banks 1 & 2 running lean. I have replaced all spark plugs, the mass air flow sensor and I am about ready to give up. I don't have a ton of money to get a diagnostics test done as my wife is due any day with our first child and I am working two jobs. Please help me figure this out. I just got back from having the check engine light read again, here are the results: TPS/Pedal position sensor, switch "A" circuit low input (P0122), System too lean bank 1 (P0171), System too lean bank 2 (P0174), Cylinder 3 misfire detected (P0303) Hopefully this might help someone with more experience than me.

You have vacuum leak most likely the intake manifold gasket

I have the exact same problem, replaced the coolant temp sensors. Same codes, same problems. Did this intake gasket fix it?

I have a 01 Ford Taurus with a new engine. After 4000 miles it blew both heads with no warning signs like over heating. This is the same problem I had before I had the engine replaced. I keep getting codes of 305 and 306 and I was told that I am running to lean. I have replaced all plugs, wires, coil packs and parts for the egr. The catalytic converters have been cleaned. The only things that haven't been replaced are the fuel injectors and the fuel pump.

Check compression and injector pulse

My 2000 Ford Taurus (185,000 miles, 3.0L DOHC) is throwing codes showing both banks running lean & Oxygen Sensors unable to switch - too lean. It also has a poor idle/miss which is most noticeable below 1000 rpm. I can rarely detect it above 1000 rpm. Once it has warmed up to operating temperature it improves, but doesn't completely go away. It is really bad when the outside temperature is 25 degrees or below.

I have replaced the spark plugs, intake plenum gasket, oxygen sensors, fuel filter, idle air control sensor/valve, and mass air flow sensor. I have attempted to detect a vacuum leak by spraying different points while the engine is running. I haven't detected any leaks.

What do I check now? I have taken it to a number of shops - a couple of who has made less intelligent "guessing" than I have.

Thanks for any help given!

Richardson5

Post the code or codes here, someone will have ideas.. some of the lean or rich codes require extensive testing, ocassionally, to find the cause.. always start with the simple things, hoses, connections, make sure everything is in it's place.. those pieces you've replaced, were they faulty or you just did it hoping to solve your problem??? I don't like to see people wasting $$$$ on parts not bad.. sometimes after doing the easy checks, it costs less to have it diagnosed, unless your local shops are well-versed and well-equipped, as you've apparently sampled a couple who were not, the dealer may be your best bet. Same thing I've been posting forever.

Thanks, is there any chance it might be out of time? If it is how would I check the timing?

not likely or will effect all cylinders
pluse cam and or crank sensor related codes
you can check using scanner if timing in SYNC

Engine Mechanical problem
1999 Ford Taurus 6 cyl Front Wheel Drive Automatic
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What does lean fault bank 1 & 2 mean

It means that the O2 sensors are telling the computer that the engine is not getting enough fuel. either this is tru, or both sensors are bad. Start with a tune up and go from there.

Engine Performance problem
1999 Ford Taurus 6 cyl Front Wheel Drive Automatic

I scanned the OBDII and the code read mixture too lean what can be done to help correct this? Could it be the O2 sensor? This the first time I ever had this problem and am not sure what to do.

O2 sensors will not give a lean condition and replacing them will not help the issue
what we find very common is the PCV valve hose
check it, it will collapse
check for vacuum leaks

I bought a used car (first mistake) from a friend of a friend (second mistake) and trusted him when he said there was nothing wrong with it (third mistake). I had it for 6 weeks when it started jerking and smoking. a coworker said the smoke was coming from the catalytic converter. Drove it home and it has sat for months. I want to get it running again but dont know what to do. I ran the codes on it and I get PO171 which in the Haynes Repair Manual says "System Adaptive fuel too lean (bank 1). When running the engine is rough and there is a "tick tick tick" sound. My husband thought that it spun a rod and he doesnt want to deal with it right now.. But I do. IF I can point him in the right direction I might get my car back. Please help. Thanks Debbie

Funny opening line :lol:

The car very well may not have not had any problems that the prior owner was aware of at that time. IT is a used car. But even new ones can come with headaches.

Here are some possibilities for the code:

Air Measurement System
MAF sensor (contaminated, damaged, malfunctioning, etc.)
Fuel System
Fuel pressure regulator (leaking, malfunctioning, etc.).
Fuel filter plugged, dirty.
Fuel pump (weak, check valve leaking, etc.).
Leaking/contaminated fuel injectors.
Low fuel pressure or running out of fuel.
EVAP canister purge valve leaking (when canister is "clean").
Fuel supply line restricted.
Fuel rail pressure sensor (incorrect reading).
Air Induction System
Air leaks after the MAF.
Vacuum Leaks.
PCV system (leak, valve stuck open, etc.)
Improperly seated engine oil dipstick.
Exhaust System
Exhaust leaks before or near the HO2Ss (exhaust manifold gasket, mating gaskets, etc.)..
EGR System
EGR valve tube/gasket leak
EVR solenoid vacuum leak
Secondary Air Injection
Damaged/malfunctioning secondary air injection system (mechanically stuck valve).


I assume this is a 3.0? Tell me the 8th digit of the VIN.

The ticking may be thin oil from it not being changed. Pull the dipstick and smell it and feel the oil. does it seem thin? Does it smell like raw gas at all?

You can check some of these yourself, w/o bothering hubby...yet. IT may inspire him :wink:

Get the info, and we will go from there. :)

8th digit of VIN is U (3.0) I forgot to mention that when it first broke down my husband did change the cam positioning sensor and found that the drive assembly was broke and he replaced it, but it continued to run rough. Also, the oil light was on before, but tonight when I started the car the oil light flickered, turned off the car, started it again and the oil light went off and has stayed off since. The car was turnied off and on a few times since it went off. Sorry, I should have said this in the first message. Oil is ok, no gas smell.. Thanks, I will be sitting near by. :P

What about the oil?

For what it matters, I don't do this for donations, but for enjoyment. I wish I could make a living at it like this :D keep in mind a donation is no gaurentee of success, but we'll give a good effort :D

I think you need to enter a number in the box, Like $5000 or $10,000 :lol:

You will need to talk to the original owner to find out what has been done to the car, unless he gave you the reciepts. such as last fuel filter etc.

the guy I bought it from bought it from an auction. He said his mechanic checked it out and there was nothing wrong with it. He told me he buys auction cars to flip for a profit for "fun". Looking back... I shouldn't have bought it. Too late now. The oil is ok, no gas smell. I found out from the VIN that the owner before the guy I bought it from was GEICO Insurance and before that it was ALLSTATE Insurance. So as far as a maintenance record I am out of luck.

what can i do to frind and fix this problem

Well no since in cryin over spilled milk I guess, some lessons can be rough :x

Odd that insurance companies owned it, don't like that sound.

Anyways, it looks like we have a list to get through.

"Pick up a code reader from a parts store, according to TaurusWheel:

Get an obdII scanner for your truck, it will pull the abs code from the datalink connector under your dash, the abs module works thru that link.... not only that, it'll work for all your obd needs, everyone should have one, not a whole bunch of money, depending on how complex you want to get. most people probably spend more in a week on coffee and doughnuts "


In the meantime,
Check the snorkel that runs from the airfilter to the throttle body. MAke sure everything is tight so there are no air leaks. Notice there is a sensor that is inline of this snorkel.
These are a common problem with this sensor, sometimes it can be cleaned, so pick up a can of electrical component cleaner while your there. Also pick up an aerosol can of intake manifold cleaner, seafoam is good also. let me know when we get to that point, or feel free to post anytime :D

1996 Ford Taurus fuel too lean (bank) one

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)

After re-reading your original post, Was the smoking converter situation ever resolved?

Hi Debbielynn!
what is the color of the smoke?
ask your husband to remove the spark plugs and tell us how do they look like?
is there any noise involve while driving?

I did a follow up on another post that had the same codes as you, The reply is as follows:


Yes, (Code P0171)

We put vacumn flex line on, replaced air plentum vacumn line under intake, cleaned fuel injection trotttle body system and cleaned mass air flow sensor -
it works fine now.....


So I guess we may be on the right path :D

I have printed all information and gave to my husband to work on. Thanks for all your help. Things move slow during the work week. Hopefully this weekend we will have ruled some things out or maybe even solved the problem. If not... I'll be back :P

got code for engine check light, acceleration is rough,

DTC 172
Lack of heated oxygen sensor switches indicates lean (bank # 1).

KOER Hard Code Go to H1
See: Pinpoint Tests\H - Fuel Control\H1 - Check For Diluted Engine Oil
KOEO Memory Code Go to H1
See: Pinpoint Tests\H - Fuel Control\H1 - Check For Diluted Engine Oil

As you can see, it is running rich. not only diluted oil but a sticking injector, clogged air filter and too much fuel pressure can cause these issues.

Roy

I have a 1996 Ford Taurus Wagon . The MIL indicator lamp is on . The first time I brought it in for inspection it failed for obd codes P0500 (vss) P0340 (camshaft pos. sensor) P0402 (egr) P0430 (catalyst system efficiency below bank 2) P1401 (dpfe sensor) . I replaced plugs wires air filter etc. Brought it back 2 months later new test revealed : P0500 (vss) Just bought this one and havent put in yet. P0340 (cam pos. sensor) going to replace this in a week before retest. P0430 (Catalyst efficiency below bank2) P1131(lack of upstream heated o2 sensor switch Lean bank 1) Could someone please tell me if replacing the front o2 sensor on bank 1 might cancel out p0430 , any input would be greatly appreciated. Thanx , blazin24

you need to clear the codes you can do so by disconnecting the battery then drive car for good 50 to 100 miles 2 ,3 ,4 days what every it take and or till check engine light return on then scan for codes and fix what you have for codes since you have a slow o2 sensor I would do that before the catalytic converter replace both sensors before and after the cat .

hi i would start by first clear computer. run when mil comes on recheck codes.because bad sensors is not the only thing that causes codes. something else is causeing the eng to run bad and cannot be adjusted .which to the ecm ,if a sensor can,t be adjusted it is out of it,s perimiters,which to the ecm it is bad. but if something is going on like tune up fuel prob cam sensor or crank sensor.these adjustments can,t be made. so before you go and spend big bucks on sensore that are not bad try and pinpoint why these codes are their . good luck billymac

sorry bmrfixit didn,t see your post billymac