p0171 p0174 lean code with low idle? black smoke?

[03explorermike]

ive spent alot of time searching the forum but with no luck, i have a 03 sport xlt 6cyl that im stumped on. its hard to start when its 45f or less and have to give it gas to start. on start a poof of black smoke and exhaust smells like unburnt gas. it idles at 500-550rpm and runs a little rough and if i tap the throttle pedal it usually dies. when driving and climbing hills when there is load on the engine there is a slow power surging as if i was slowly letting off then pushing on the gas. drivability seems to be good until it started dieing at stop lights. it smells rich all the time. im getting about 11mpg.

i checked for vacuum leaks with starting fluid and found none. i tested the egr and its working. i cleaned the maf sensor with "maf clean" with no effect. the fuel pressure is 68psi. chilton says 28-45psi?. i have not thrown any parts in it yet because im trying to find whats bad. at this point i wish i had a obdII scanner but am hoping someone knows whats wrong.

maf sensor?
fuel pressure regulator?

Thanks for any help or advice!

 

[2000StreetRod]

returnless fuel system

The fuel pressure listed in your Chilton's book is for the return fuel system with a vacuum controlled fuel pressure regulator mounted on the fuel rail. You have a returnless fuel system with the fuel pressure regulator in the fuel tank and a fuel pressure damper on the fuel rail. Your fuel pressure should be about 65 psi no matter what the engine load. Yours sounds OK.

Your too lean diagnostic trouble codes (DTCs) do not match the engine conditions you're reporting - too rich. There must be a reason why the PCM thinks it can't make the air/fuel ratio rich enough. One possibility is a defective engine coolant temperature (ECT) sensor is reporting the engine as cold when its not and the PCM is enriching the a/f ratio excessively. However, that should only be a problem when the engine is already warm. Another possibility is the PCM thinks the engine is under heavy load when it's not. The MAF sensor and the TPS are the main sensor the PCM utilizes to determine engine loading. You stated that you cleaned the MAF sensor. Do you have a stock air filter or an oily aftermarket filter? I suggest that you test the MAF sensor and the TPS:
MAF Sensor Test Procedure
I believe that your model will be limited to 3,000 rpm in Park and Neutral
TPS Test Procedure

Another possibility is that your pre-cat O2 sensors are bad. Do you have one or two? If you have two, it is unlikely that both would go bad at the same time unless you contaminated them with something (silicone spray) or inadvertently disabled them.

 

[03explorermike]

thanks for the fast answers.
wow what a coincidence. i read your thread on testing the maf and got this the other day. wasnt sure if these numbers were close enough for it to check out ok

RPM Voltage IS
should be
550 0.8 .55
1000 1.0 .70
1500 1.25 1.15
2000 1.4 1.33
2500 1.55 1.62
3000 1.65 1.93
3500 1.9
4000 2.1

 

[03explorermike]

The voltage did increase smoothly from .55v to 1.93v

 

[03explorermike]

i tested the tps and it went from .96v-4.64v smoothly.

the engine is limited to 3,000 rpm in park and n.

it has a stock clean air filter that was replaced last summer.

there are 2 o2 sensors before the cat that never have been out of the exhaust and should be free from grease or silicone spray.

 

[2000StreetRod]

MAF sensor voltage

I'm not familiar with your 2003 intake configuration so I don't know if you have the same MAF sensor. I seem to remember that your Sport is more like a Sport Trac than my Sport. Do you have the single piece intake manifold?

Anyway, your MAF sensor idle voltage would be much too low for my engine. That voltage is comparable to what I have with my 90mm Lightning MAF sensor. The larger diameter results in a lower air flow speed for a given air flow volume so the voltage output is lower. It seems like either your air flow is very low or your MAF sensor is defective. But your MAF sensor readings are reasonable at mid range rpm. If you have a blocked intake or exhaust then your airflow should be less than mine at mid range. I guess the very rich mixture could be choking your engine at idle reducing the airflow. How does the engine idle with the MAF sensor connector disconnected?

 

[swshawaii]

OBD Codes P0171 and P0174


This code is a common code to the Sport Trac. It is normally the elbow that is located under the throttle body. It tends to crack on the bottom and needs to be removed to examine it. You can replace it with a small piece of heater hose that is 5/8 inch. But heater hose is a quick fix. The hose will soften and collapse causing other problems. We recommend you purchase a PCV elbow or the replacement part form a dealer.

 

[03explorermike]

OBD Codes P0171 and P0174


This code is a common code to the Sport Trac. It is normally the elbow that is located under the throttle body. It tends to crack on the bottom and needs to be removed to examine it. You can replace it with a small piece of heater hose that is 5/8 inch. But heater hose is a quick fix. The hose will soften and collapse causing other problems. We recommend you purchase a PCV elbow or the replacement part form a dealer.

Thank you. ill check it out. i did spray starting fluid on it when checking for vacuum leaks and the idle did not change

 

[03explorermike]

I'm not familiar with your 2003 intake configuration so I don't know if you have the same MAF sensor. I seem to remember that your Sport is more like a Sport Trac than my Sport. Do you have the single piece intake manifold?

not sure if its a 1 or 2 piece manifold. its composit. the gasket set shows lower and upper gaskets so it must be a 2 piece.

Anyway, your MAF sensor idle voltage would be much too low for my engine. That voltage is comparable to what I have with my 90mm Lightning MAF sensor. The larger diameter results in a lower air flow speed for a given air flow volume so the voltage output is lower. It seems like either your air flow is very low or your MAF sensor is defective. But your MAF sensor readings are reasonable at mid range rpm.

my maf is the maf/iac combo 1L2F-12B579-BA
i did some research and it come from the factory on

EXPLORER 01 w/flex fuel │
│ EXPLORER 01 w/o flex fuel; 2 Dr (Sport); from 3/29/00 │
│ EXPLORER 01 w/o flex fuel; 4 Dr, Sport Trac, from 3/29/00 │
│ EXPLORER 02-03 2 Dr (Sport) │
│ EXPLORER 02-03 4 Dr, Sport Trac │
│ EXPLORER 04-05 Sport Trac │
│ MUSTANG 02 6-232 (3.8L) │
│ MUSTANG 03 6-232 (3.8L) │
│ MUSTANG 04 6-232 (3.8L) │
│ MUSTANG 04 6-238 (3.9L) │
│ RANGER 01 6-245 (4.0L), ID 1L2F-BA │
│ RANGER 02 6-245 (4.0L), ID 1L2F-BA │
│ RANGER 03 6-245 (4.0L) │
│ SABLE 01-03 (6-183, 3.0L), DOHC │
│ TAURUS 01-03 (6-183, 3.0L), DOHC │
│ WINDSTAR 01-02 (6-232, 3.8L), ID 1L2F-12B579-AA │
│ WINDSTAR 01-02 (6-232, 3.8L), ID 1L2F-12B579-BA │
│ WINDSTAR 01-02 (6-232, 3.8L), ID RM1L2F-12B579-BA │
│ WINDSTAR 03 (6-232, 3.8L), ID 1L2F-12B579-AA │
│ WINDSTAR 03 (6-232, 3.8L), ID 1L2F-12B579-BA

 

[03explorermike]

my sport looks more like a sport trac under the hood
explorer sport

02 explorer

 

[2000StreetRod]

MAF sensor PN

The part number on my stock 55mm MAF sensor is XF2F-12B579-AA. It probably has different air flow vs voltage characteristics than yours which would be reflected in the data tables in your PCM.

Would you please state where your windshield washer reservoir is located? I have a tank for coolant and a tank for the windshield in a row on the passenger side. I'm looking for a way to save some space for a possible future modification.

 

[03explorermike]

sorry to get back to you late on the resevoir location. they are both in a row on the passinger side.

 

[03explorermike]

How does the engine idle with the MAF sensor connector disconnected?

i tried unpluging it and running it today and it ran super rough.

ive noticed that it hasnt been smoking on start up latey. in fact it has had a low but speratic idle latley. i know the plugs show a lean run condition and need to be changed but am afraid of ruining the new ones.

 

[2000StreetRod]

tanks

sorry to get back to you late on the resevoir location. they are both in a row on the passinger side.

Your tanks and their location are identical to mine. The only real difference I see in your engine compartment is the location of the oil filler tube (mine is on the driver side valve cover) and the intake manifold.

If your engine is actually running rich it will shorten the life of your catalytic converter. It's puzzling to me that you get black smoke and smell unburned fuel indicating a rich condition but your codes are for a lean condition. I think it would be helpful to pull a spark plug from each bank and confirm by inspection if the engine is running lean or rich.

Did you check the elbow as suggested by swshawaii?

 

[03explorermike]

Did you check the elbow as suggested by swshawaii?

Yes I did check it again with no leaks. Just to confirm it I pluged the pcv inlet on the intake with no difference.

 

[ncranchero]

Just for kick and giggles physically check the elbow & for a stuck pcv valve. This is every day stuff on the Sport Tracs! Hose cracks on the bottom side.

 

[03explorermike]

wow. i think you were right. i felt the bottom of it and when i pushed up it creased at a crack. im going now to get a replacement to see if it works. the starting fluid trick did not find this gaping hole. i just ordered a diy vacuum smoke tester and ill check for other leaks

 

[03explorermike]

i wonder if why i was getting black smoke on start ups was because the plugs are shot from running lean and having to give it alot of gas pedal to get it running. the electrodes are most of the way gone on the plugs

 

[the_ferret]

My elbow won't come loose at the connection going in to the intake. Any tips to get it off?

 

[swshawaii]

Like any hose that's been subjected to heat for a long time, it will be snug.
For clearance, probably easier if you disconnect the hose above the elbow.
Use a channel lock plier with a cloth for protection. Go easy, it'll come off.