I have a 2001 expedition with codes p0171 p0174. Sometimes but not always, It also has long cranking times before it starts. once its running its runs great. its 5.4 L 117k miles. Any thoughts on this? thank you
2001 expedition p0171 p0174 WITH LONG CRANKING TIME
- Thread starter n.shift
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I forgot to mention it only does this when cold. when I say cold, I mean 30 degrees outside. Im thinking leaking intake gasket. Because when its warm, it doesn't do it. maybe do to the rubber gasket being slightly swollen...but any input would help
Fuel filter? You'd be surprised what floating trash in a fuel filter can do. Simple stuff first...
Check for bad vacuum hoses, loose clamps, dirty MAF sensor, easy stuff first, then go from there. IIRC P0171 and p0174 indicate lean conditions on both banks, so it's going to be air leak or restricted fuel.
Check for bad vacuum hoses, loose clamps, dirty MAF sensor, easy stuff first, then go from there. IIRC P0171 and p0174 indicate lean conditions on both banks, so it's going to be air leak or restricted fuel.
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The freeze frame data is suppose to point you in one direction or the other. Here are my results any ideas? Suv runs great. Starts normal 99.5% of the time. Very long cranking time the othe .5% of the time. Plenty of power. Doesn’t die or doesn’t run rough. Just the 2 codes and every once in great while long cranking time
Mine was doing the same thing. Engine cold, it would sometimes be really hard to start. I was thinking intake leak, timing off, bad crank sensor, bad IAC valve, etc. Freeze frame data and codes were the same. Turns out there was trash (lots of it) in my fuel filter. Changed it, and the problem went away. In your case it could be moisture or water, since you said it happens at near freezing temps. I'd start there.
Will do. Thank you
Ok I just created an account to answer this for you. I have a 2001 expy 5.4 4x4. It was doing exact same thing. Took me a while to figure it out. What fixed it was changing the whole fuel pump. The fuel pump has a check ball in it to keep pressure when shut off to my understanding. When it gives up it creates this problem. I changed several parts until I got it. You can get the whole part with float and everything pretty cheap on eBay. That's what I did.
Definitely a possibility. I always start with simple stuff first. Fuel filters are cheap and easy.
Yes it is possible. I tryed that on mine. Hope it works better for you. I also try fuel pressure regulator. And changing the core on the fuel rail. Where you check pressure. To my understanding the reason for the long start time is because when the fuel runs back in the tank air gets in the lines. If that helps. The my fuel pump it's self was not bad. Still made correct pressure. Showed no signs while driving it. Was just hard starting from time to time. Then it got to be more often. I think on eBay I payed $60something for the whole thing.
I could very well have 2 problems at once. I’m really leaning toward vacuum leak for the p0171 and p0174 codes because if you look at my freeze frame data,the codes where thrown at idle. But again, I’m just leaning. More research is needed. The check valve in the pump might def be the problem for long crank times on occasion. I’ll be checking fuel pressure soon. Ty
Was that right after start up. Will also tell you mine was throwing the same codes with the problem. I had no vacuum leak. Everything you are experiencing is the same as I was. That's why I am expecting it to be the same problem. But I could be wrong
DF5.4
Full Access Members
My 07 had the same symptoms and codes. It was the fuel pump assembly. The regulator in the assembly was bad. Check your fuel pressure at the rail.
Don't over think it. They were thrown at idle, but that could be because that's when your engine went into closed loop mode and started taking readings from the oxygen sensors. Lean conditions while running at operating temp are either a vacuum leak or restricted fuel supply. Fuel filter clogging can cause long starts AND lean conditions. BTW I also had good fuel pressure before changing the fuel filter.
Just so you know, my experience with my expy is extensive. I recently had the engine and transmission out. The straw that broke the camels back that made me decide to do it was.....intermittent long starts. Long story short, I overhauled the tranny, changed all engine gaskets, cleaned throttle body, egr, and iac, replaced intake manifold, changed spark plugs, changed a hose or 2, and changed timing set. None of that fixed the intermittent long start. It was just the fuel filter. Moral of the story: don't over think it. Simple stuff first.
DF5.4
Full Access Members
Lean codes means either too much air or not enough fuel. The other thing the shop told me was the fuel pump driver module could be bad. Mine didn't have one but they are mounted to the frame and take a beating.
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Exactly. Just don't go sinking $$$ while overlooking a $14 fuel filter
I had a Lincoln Town Car(4.6l) do the same thing. It would take sometimes, 4 tries to start, when cold. It ran fine the rest of the time. It was the fuel pump. There is a check ball that holds pressure, in fuel line. It failed and fuel was draining back to tank. Find your fuel rail. There is a service cap with a Schrader valve. Let vehicle sit over night. Take a screwdriver and bleed some fuel out. It should spray out, with a little back pressure(beware). Mine was bone dry. After finally starting, I checked and sure enough, had built up pressure. I think it may of had something to do with Ethanol, in fuel and being run down to almost empty(by previous owner).
Mike Rush
New Member
Clean throttle body and maf sensor helps with long crank to start
laffinguy
New Member
I got the exact same two codes, and it was a $0 simple fix, so fingers crossed this helps you. If you have changed coils or spark plugs recently, or worked around the driver side of your engine, its is really easy to accidently disconnect a vacuum hose off of your DIFFERENTIAL PRESSURE FEEDBACK EGR SENSOR. There are 2 vacuum tubes that hang from the bottom of this sensor and the slightest amount of pressure from your hand, tool, or part will disconnect one or both of these hoses. This sensor hides toward the top of the engine maybe a foot from the firewall, so its hard to find. But finding the hoses are easier as they tend to drape over the driver side valve cover. If either of those hoses is disconnected that's your problem. If one is loose it's connection is located beside the other hose connector. Good luck.
docraymund
Full Access Members
Check your long term fuel trim again. If it is a vacuum leak, increasing the engine rpm would bring the values down because of the increased air flow. If it didn't go down, that means it's not a vacuum leak but a fuel delivery issue.
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