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2003 Ford supercrew with the small v8. For the past year running like total crap. Code thrown is lean condition. Have replaced EGR, cleaned out throttle body, replaced O2 sensors, replaced cats, replaced coils, plugs, maf and tp sensors, and it still shakes like a mother, smells like raw gas coming out of the exhauste and keeps throwing out the same freaking code! I will not trade or sell since it is mine and paid for, but enough is enough. The dealership said they didn't know what was wrong since their equipment only says bad O2 sensors even though they are all new. Any ideas?

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I'd suggest the ford truck forums. They have helped fix three problems with the company diesel F350 that had several mechanics confused.

 

The code thrown and the problem your seeing may not be related.

 

For example, our diesel had a problem of running really really rough in park. When it was switched to neutral it ran fine, which meant it was the transmission range sensor. Once that was replaced it ran fine.

 

You could have a plugged filter or weak fuel pump. But asking truck questions to firearms enthusiasts won't get you as far as the truck guys.

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Post the codes.

 

I had a 2000 Taurus that had emissions and rough engine problems. Don't remember what the codes were.

 

I also replaced the EGR but that didn't fix it. Finally found that there was a 90 degree rubber elbow pipe that rotted out

and was sucking air. It was under the intake manifold and a real PIA to get to it. Dealer wanted about $900 to fix it.

 

I bought the replacement part for $8 and pulled the manifold myself, it took about an hour and a half or so and it was fixed.

You're supposed to use a new manifold gasket, but I didn't and it ran fine.

 

The rubber pipe rotting out turned out to be a common problem, I just had to search online long enough to see what

everybody else did to fix the codes I had.

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Fuel pressure regulator?

Doesn't really make since that its throwing lean code though. But would totally cause the other problems. Does it have a common rail? Can you throw a gauge on it?

If so test operating pressure and also do a leakdown test, turn off the truck and see how long it takes for pressure to drop. A leaking injector could be the issue. I've seen o2 sensors bad out of the box. Other things, wiring from engine cotrol computer to o2. If you have the pin out you could that that wiring. Could always be the computer as well.

These are not vehicle specific, but blanket test for the issues you are having.

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If you smell gas in the exhaust, you're probably not really running lean. Diagnosing a rich condition when the PCM thinks that it has a lean condition can be tough.

 

Pulling the spark plugs and checking color will confirm this and also will allow you to pinpoint the trouble cylinder, because it's probably just one or two cylinders that are causing the problem. This is important to find out, it will help you focus on a specific area of the engine.

 

You could also find that all cylinders are effected, which actually narrows things down - e.g. now you know you have a central point of failure upstream in the fuel system.

 

Stuff I can think of

 

- O2 sensor melted or chafed wires causing short to ground and false lean signal, this would cause the PCM to overcompensate with a rich mixture.

 

- One or more leaking injectors. You may want to run some Seafoam in the fuel several times.

 

- Leaking intake manifold gasket - this can be tested by spraying carb cleaner all around the intake manifold. If idle rises, you found a leak. A lot of the late 90s/early 2000s Ford with plastic intakes had a tendency to lose intake stud bolt torque over time and had to be retorqued.

 

- Failed fuel pressure regulator. The FPR can sometimes fail internally and leak pressurized fuel through the vacuum line.

 

- Stuck open evaporative canister purge valve - this can allow excess fuel vapor to be pulled in via vacuum.

 

- Weak fuel pressure - filter or pump, as mentioned by csspecs.. May be enough to run correctly at idle but not at load. If you were to test fuel pressure at the fuel rail (there is a schrader valve here for testing) you should see 35-45 PSI while running or with key ON. You can test this with a cheap screw-on dial-type tire pressure gauge, but the seals will probably only last a couple of uses.

 

- Also, I don't know about Fords, but I know some Chryslers have trouble with certain types of spark plugs with coil-on-plug ignition. For example my Jeep 4.0 will not run right with most any of the fancy multi-prong plugs on the market today, and really runs best with a standard single-prong plug. Something about the impedance of this design just doesn't jive well with the pulse that the small coils send out.

Edited by mancat
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Mancat beat me to it, but I'd emphasize.

 

You smelling gas at the exhaust would  not indicate lean. I'd trust my nose before I trusted the electronics. I'd first look to my spark plugs and see what they look like.  You should be able to find a good bit there.

 

I had a 2007, and have a 2011, but not much problem-wise, so I cannot be much help, but to say, the forums for f-150 are generally awsome.  I find someone has always asked, and gotten answered, my question before I ever ask it.

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If the carb cleaner around the intake trick shows a leak inspect the manifold for any cracks. Clean injectors. Check o2 sensors (buy one Bosch 15718 - it will work for all 4 positions) make sure your MAF is working appropriately if you have a multimeter... maybe get an pcm for it?

Clean the IAC as well with intake cleaner, could be gummed up

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Sounds a lot like a vacuum leak.  Unmetered air getting into the clyinder, 02 detects lean spike and dumps fuel.   The carb cleaner on the manifold trick is a good one, but I like to use one of those butane torches (unlit ofcourse)  The gas is a lot better than spraying a flamable liquid all over everything.  Find the vacuum leak, find the problem in my .02

 

A bad 02 sensor will also cause the ecu to dump fuel, pull timing, and be low on power.

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When you get a lean code your vehicle is actually dumping fuel trying to correct it, you've already replaced a lot of parts that can cause it so unless you screwed up an install you can rule all them out. I worked for ford for 12 years and have rarely seen an o2 sensor cause a lean code. In fact I've rarely ever replaced one unless it was in a cat that burnt out damaging the sensor. There's a lot of rubber lines on that motor that after time wear out, check them. A common one is on the drivers side back of the intake that is a pain in the ass to get to and easy to screw up replacing. Find a different dealer or mechanic who will smoke test you motor.

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I'm remembering I had another emissions thing on the Taurus.... I think it was the EGR pressure sensor.

Bought a new sensor at Autozone and still had the problem. That made no sense though, the sensor had to be the problem.

 

So I bought a new sensor from a Ford dealer and then it was fixed.

So the new sensor from Autozone was bad.

 

Not to pick on Autozone, I really like them a lot. They take back parts that most other auto stores will not.

I try to buy all of my parts from them.

 

As was said earlier, sometimes the code you are getting has nothing to do with the problem.

I was getting something like "lean cyl #2" on one of the the EGR related things.

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Probably the "differential pressure feedback EGR" sensor (DPFE), they constantly fail. We had to replace it a couple times on our 96 Explorer.

 

The DPFE tells the PCM whether or not the EGR valve has actually opened.

 

Usually the Ford PCM will signal on a DPFE failure and give a specific code for that.

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Check the EGR buy pulling a vacuum on it...you can do this buy just sucking on a flexible piece of vacuum line (engine off!), or with a pump with a vacuum gauge.  It should hold vacuum, if you can draw air through it or bleeds off the vacuum quickly its bad and needs replaced.

 

When the EGR valve is open all the time it will throw a lean code and try to correct itself by dumping more fuel in order to correct the ratio. You can trick the EGR system into thinking it is working right buy pulling the EGR vacuum line off the EGR valve and connecting it to the REF (reference) port on the DPFE sensor.  Buy pulling a continous vacuum on the REF port it will prevent the sensor from reaching the conditions it's looking for to increase the fuel to air ratio.  By tricking the DPFE sensor like this the computer will think everything is gravy and your engine will run/idle properly and return your city mpg's/performance back close to normal, your highway mgp's will suffer however because this trick also prevents the DPFE sensor from reaching the conditions it needs to reduce the fuel to air ratio likes its intended to when your cruzing at a continuous engine speed...the engine will still run fine at cruzing speed, however.

 

I've had and diagnosed the exact same problem with 2 fords I've owned and I helped a buddy of mine diagnose the same problem.

Edited by Barnett3006
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Probably the "differential pressure feedback EGR" sensor (DPFE), they constantly fail. We had to replace it a couple times on our 96 Explorer.

 

The DPFE tells the PCM whether or not the EGR valve has actually opened.

 

Usually the Ford PCM will signal on a DPFE failure and give a specific code for that.

 

Yep, that was it.

 

Too bad cars have become so complex with hundreds of parts, hoses, sensors, etc. that really have nothing to do with making them roll down the road. It would be so much better to have cleaner fuels (alcohol for ex.) and not have all of the emissions junk on the cars.

Edited by Spartacus
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ford had the great idea around that time to pressurize the fuel system on those trucks. their idea was to use pressure to push fuel through the lines so the pump had to work less. the raw fuel smell could be vapors from the fuel tank. i have seen it a couple times where the hose for the filler neck breaks and you smell fuel all the time and it runs lean. also i have seen lines come loose on the fuel filter.

it could be: hole in fuel line, filler neck tube, top of fuel tank gasket, hole in fuel tank, and some times as easy as a gas cap

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2003 Ford supercrew with the small v8. For the past year running like total crap. Code thrown is lean condition. Have replaced EGR, cleaned out throttle body, replaced O2 sensors, replaced cats, replaced coils, plugs, maf and tp sensors, and it still shakes like a mother, smells like raw gas coming out of the exhauste and keeps throwing out the same freaking code! I will not trade or sell since it is mine and paid for, but enough is enough. The dealership said they didn't know what was wrong since their equipment only says bad O2 sensors even though they are all new. Any ideas?

Does it run any different hot or cold?

Brand name on parts will make a difference. And the cheap universals should be avoided.

What does your short term fuel trim run at?

As said before spray the intake plennum and watch the st fuel trim. If it changes drastically then your seals are bad.

If this is the composite intake set up.they are known to flatten and leak. they are too hard and don't seal.

 

 

 

These are good for misfiring on the passenger rear cylinders where the heater hoses run. The hose leaks and fills area and shorts coil.

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ford had the great idea around that time to pressurize the fuel system on those trucks. their idea was to use pressure to push fuel through the lines so the pump had to work less. the raw fuel smell could be vapors from the fuel tank. i have seen it a couple times where the hose for the filler neck breaks and you smell fuel all the time and it runs lean. also i have seen lines come loose on the fuel filter.

it could be: hole in fuel line, filler neck tube, top of fuel tank gasket, hole in fuel tank, and some times as easy as a gas cap

all fuel injection systems operate with a pressurized fuel system, nothing unique about ford.

 

some of the early central injection/"throttle body" injection systems used a lower pressure (about 15psi) but it was still required.

 

 

unfortunately as far as testing EGR goes, I believe this generation of Ford EEC uses a solenoid controlled EGR valve that cannot easily be manipulated manually. he did already replace the valve.

Edited by mancat
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It sounds like your gas-block port is partially obstructed causing the bolt to cycle poorly and throw a code. :)

 

 

 

 

As Mancat stated, check the O2 sensor wires (some have more than one sensor) for damage and continuity.

 

If the computer thinks its running lean it would try to compensate by running rich.

 

Start with the simple stuff.

 

I found a post where a guy was having similar problems and O2 code on his GMC. A new fuel pump fixed it.

 

http://www.cargurus.com/Cars/Discussion-t14325_ds534062

Good luck.

Edited by Sim_Player
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A sticking egr will rarely cause a lean code, the egr is normally open on part and full trottle, it can cauSe a lean code at idle. But it will also cause a rough idle. You need to get the freeze frame data for the code. That will tell you when it is happening, if its at idle then possible egr or most likely a vacuum leak, unless its a real bad leak it wouldn't affect it while driving. MAF sensors are very delicate maybe you were too rough replacing it, or do you have a k&n filter on it? Those are notorious for contaminating maf's and causing said problem. One way to isolate the MAF is to disconnect it then drive the vehicle after making 3 wot pulls if the problem corrects itself then the MAF is the culprit.

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Great timing on this thread , my wives  truck has been throwing the dreaded po420 code , after replacing all 4 o2 sensors its  still throwing the same code ....... I picked up an obd2 to usb cable off of fleabay "should be here today" I hope it helps tracking down what this motor is doing , will report back :]

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Great timing on this thread , my wives truck has been throwing the dreaded po420 code , after replacing all 4 o2 sensors its still throwing the same code ....... I picked up an obd2 to usb cable off of fleabay "should be here today" I hope it helps tracking down what this motor is doing , will report back :]

That's a cat efficiency code, another one that is rarely an o2 sensor, most likely the cat. A quick test is to take an infrared thermometer and check the temp of the pipe going into the cat and the pipe going out there should be at minimum a 50 degree difference with the outgoing temp being higher. If there isn't then the cat is no longer working.
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