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2003 5.4l P0171 P0174 Solved. Repair Completed

 
  #1  
Old 11-17-2018, 03:18 PM
TheRed
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2003 5.4l P0171 P0174 Solved. Repair Completed

Hello, everyone. This post is not a request for help, as the work is done. It's just a record of what I recently did to get rid of these codes and some other problems.

This site has been a huge help to me over the last several years and has been my go-to resource for all my Ford repair questions

Hopefully this post can be of use to someone else.

I have a 2003 E350 Super Duty.
5.4l gas.
115,000 miles.
Symptoms - PO171, P0174, slow starting, though the battery was strong and the engine turned over very well, lots of shuddering due to misfires.

Code Readers:
Forescan Lite on my Ipad
An Actron CP 9580A 'Autoscanner Plus'

I purchased this van a year ago for work. It had been used and maintained by a local HVAC company since it was new.

It had been sitting for up to two years before I bought it. Since purchasing it I've driven it a little just to 'exercise' it.
It has average body rust for a 15-year-old Minnesota van (we use salt on the roads here).
However, it has quite a bit of unusual corrosion on the fasteners throughout the body, frame and engine, as well as on some of the electrical connectors. I think this has to do with how it was stored (or to say it better, stuck out in a field) for those two years. In any case, there's an awful lot of rusty fasteners on the vehicle.

Bit by bit I've been knocking off the projects that need to be completed before I load all my tools in the back and start using it for work.

First, the rear brakes were seized up. Almost as soon as I had it home from the DMV I replaced both rotors, calipers and pads. The fronts were in good shape. Now the braking is excellent.

Next, I hunted and found some good used tires on aluminum rims on Craigslist and replaced the 4 worn out tires and hubs.

Not long after that the rear stud on the passenger-side exhaust manifold gave out, and I spent some time trying to weld a nut on the end of the stud (broke just proud of the manifold surface) so I could turn it out and install a new one. Failed. So, I bought a pressure fitting from Kral Auto Parts and tried to squeeze the back of the manifold against the block. So far it's not working great. But, almost as soon as the manifold stud broke the engine started throwing codes and the hunt for the solution lead me away from the exhaust system.

I'd read here that leaky manifolds will lead to codes, but I found uniform fuel trims on the two banks and so decided that the manifold leak on Bank 1 was most likely not the problem.

The long term fuel trims were both right around +10 at warm idle and up around +23.5 under load.

Once again I studied the forums here - as well as Youtube videos on fuel trim - and learned that both a vacuum leak and a fuel pressure problem can lead to these kind of trims.

I checked out the engine hoping to find a vacuum leak. I did not find one.

I did sound tests for the fuel system:
1) I listened for the fuel pump right after turning the key on and would hear it.
2) I listened for the fuel pump relay right after turning the key and would hear it clicking away.

Since the relay was working and the pump was at least being energized I decided to check the fuel pressure.
I went to Napa and rented a fuel pressure tester (no charge if returned on time).

Side note on the Schrader valve: The Schrader valve was so far down below the top of the threaded pipe it's housed in that the fittings from the tester kit would not depress the valve stem, though I made sure the fitting was fully seated. I ended up removing the Schrader valve from the pipe and just connecting the pressure gauge with hose clamps and some rubber lines from the testing kit.

Sure enough, the engine had zero fuel pressure with the key off (should be around 35 psi as I recall) and never had more than 20 psi. When I'd turn the key on the pressure would bump up to 2 psi for a heartbeat then drop back to zero. If I cycled the key on for three seconds, then off and quickly on again (repeat 3 or 4 times) I was able to get fuel pressure up to 10 psi, but never any higher.

Based on my research here I concluded that the fuel pump was the problem. I didn't want to tackle the repair myself.
I found a nearby shop with high ceilings (my van with ladder racks is about 8' tall) and a lot of fleet experience who confirmed my tests and replaced the fuel pump.
To drop the tank, replace the pump, replace the tank hangers and also the filler tube (very, very rusted) they charged me $985.00.

Upon picking up the van two days ago I noticed that it started immediately for the first time ever and lost its sluggish response. However, the shuddering from misfires was still there. In one 15 minute freeway ride Forscan measured over 450 misfires.

Today, I figured out how to run the Mode 6 tests with my Forscan Lite and was able to narrow the misfire down to cylinder 5.

I purchased an extra long 5/8" socket (about 6" lon, as was recommended by another poster on this site) one new plug and one new coil pack.

After installing these two new items the van runs great! No more misfires.

That's it for now. Hope this can be of use to some other newbie. Please pardon the length of this post. I had no time to make it shorter.

The Red.





 
  #2  
Old 11-17-2018, 04:33 PM
NICKSAN
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Glad to hear you got it all sorted out.


 
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Old 11-18-2018, 05:16 AM
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Those two DTC's for Lean Bank 1 & Lean Bank 2 have a ton of causes but you were smart to study in advance of digging in changing parts. Here's a YouTube video I found fascinating for those interested in fuel trims etc:
One more from another automotive diagnostic genius:

Your fuel pump replacement costs by a shop were VERY fair---when my '03 E250 failed it was right at $800 as a side job for one of my customers who own a large trucking company. Motorcraft pump , new Ford tank straps, filter and a patch welding to the unknown leaking fuel tank (only discovered when straps were removed). The damnedest thing was not one symptom presented itself before the failure---was quite a shock.

I also have an Actron scanner (same version I think) and have FORScan installed on a laptop with the ELM adapter ready to do. My '05 E350 has what I'm sure is a low-grade misfire on the brand new Ford reman'd engine. The original COP's have only 143K miles with new plugs and boots so that has to be sorted out. I'm kinda looking forward to working with FORScan.

Thanks for sharing and taking the time to create your post---without a doubt it'll be helpful! Reps Sent!
 
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Old 11-18-2018, 06:40 AM
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Iíve said for years ďif you get p0171 and 174 then itís ALWAYS a vacuum leakĒ.
I like to learn though. And I now see the logic of low fuel pressure causing that also.
 
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Old 11-18-2018, 01:21 PM
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Originally Posted by Im50fast View Post
I’ve said for years “if you get p0171 and 174 then it’s ALWAYS a vacuum leak”.
I like to learn though. And I now see the logic of low fuel pressure causing that also.

Not "always", but "usually" would be correct. Vacuum leaks probably account for 90%+ of the occurrences.

Dual "lean" codes are going to be caused 1) by something common to both banks 2) and will result in either an "over-aired" (unmetered or incorrectly metered) or 3) an "under-fueled" condition as sensed by the computer.

A weak fuel pump would be in the "under-fueled" classification.

A dirty MAF would under report air mass coming into the system and the PCM would respond by adding extra fuel trying to compensate. Similarly, a vacuum leak downstream of the MAF sensor would also result in an "over-aired" condition with those same results.

FWIW, O2 sensors are NEVER the cause of this code pair.

Also, if left uncorrected for very long, one can usually expect the converters to become damaged due to the excess fuel in the exhaust.
 
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Old 11-20-2018, 03:45 PM
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Thanks for this post. I get the same codes (both banks lean) under load and my fuel trims are way out of whack almost exactly as you described (97 E250 5.4 235K miles).

Also, the first start of the day is really crappy on my van - I cranks and fires right up, but runs like crap - very rough idle and will die. Key off and restart and it runs great all day.

I need to check the records but I'm pretty sure I put a fresh fuel filter in it recently.

I cannot find any vacuum leak.

Time for a fuel pressure check (which I would not have done until a last resort without this post).
 
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Old 11-20-2018, 04:57 PM
TheRed
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JWA;

Thanks for the reply (and the reps!).

I'd watched that first video and I'm very glad to see it attached to this post. Now I'll know where to find it when I need it again (which will be very soon).
I didn't make it through the 2nd while I was in the middle of the project, but will watch it soon as well.

I have another E250 that is throwing 0171 and 0174, and I'm looking forward to more practice with fuel trim analysis as I try to figure it out.
 

Last edited by TheRed; 11-20-2018 at 04:58 PM. Reason: forgot to give name of poster I was responding to.
  #8  
Old 11-20-2018, 05:03 PM
TheRed
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jbwheels,

I hope you don't have to replace the fuel pump! I'll look forward to learning what you find.

I had watched the first video JWA posted and found it really informative. Confusing? Yes. I need to watch it again.
But informative nonetheless - the bits I was able to grasp helped me find my problem.
 
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Old 11-21-2018, 04:16 AM
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The first video was a lucky find for me---before I knew a very little of fuel trims and the lean bank codes but the presenter has a great way to share info, its not boring and he makes it very easily understood. The second by ScannerDanner is more in-depth at the hands-on level and is useful in its own way. Watching either one a second time would be good--I'll do that myself one day too.
 
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Old 12-22-2018, 05:30 PM
jbwheels
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Finally got around to hooking up my fuel pressure gauge.
These numbers look low.
28psi idle.
low to mid 30s under load at best
mid 30s KOEO
I did not trip CEL during this run.
I'm going to change the filter this afternoon and retest but I doubt it will change - I replaced the filter within the last 10K miles.
Thoughts?
My fuel pressure test video (the sound sucks - sorry - I'm a complete amateur):
 
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Old 12-22-2018, 05:42 PM
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From what I've found in the Haynes manual your numbers are a bit low. But nowhere near as low as my van's were.
I'll be interested to see what other folks say about your numbers as I have another E350 with the 5.4l with numbers like yours.

Are these fuel pumps (yours and mine) on the way out, but working well enough for the time being?
 
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Old 12-22-2018, 07:18 PM
jbwheels
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Changed the filter.
I saw 30 at idle.
Shut it off and pulled the vacuum line of the regulator and fired it back up.
FP climbed to 33-34 range and does not move now with or without vacuum.
Leads me to think the FPR died on me.
Will check again tomorrow maybe with my other gauge.
 
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Old 05-10-2019, 09:46 PM
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I know I hijacked this thread...

I finally fixed my lean codes by replacing the MAF.

Fuel trims normal now so no codes.
 
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Old 05-11-2019, 04:05 AM
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Originally Posted by jbwheels View Post
I know I hijacked this thread...

I finally fixed my lean codes by replacing the MAF.

Fuel trims normal now so no codes.
Sometimes a thread jacking isn't the worst thing----in this case the DTC's of P0171 & P0174 do not exist from just one failed part etc---its a symptom of an induction or fuel pressure issue. As this tread evolved we see several suggestions what to check including monitoring both short and long term fuel trims.

IMHO as long as the conversation eventually leads to a solution its all good--most of us probably learn by doing, following ideas here adds to our personal knowledge base. Sometimes we're able to pass that knowledge on to others, the whole purpose of forums like FTE!
 
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Old 05-11-2019, 08:30 AM
TheRed
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Great! I'm glad to hear you didn't have to put in a new pump.

Thanks very much for letting us know 'The Rest of the Story'.

My other 5.4l is still running but throwing more codes. I have already replaced the MAF and that didn't seem to improve things,
so it looks like I'm heading for new fuel pump.

This time I plan to do it myself. I'm going to cut open the floor in back and replace the pump from above.

It looks like Rock Auto has the Motorcraft for about $300.00, though I may buy something cheaper.
 

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