Couple code's..

[77mud]

I'm currently working on my mothers 2000 Expedition with 5.4, it has 2 code's P0171 and P0174 for bank 1 and 2 lean. so far Ive checked the MAF and it has a little dusty but nothing terrible it also had one of those "tornado" things in the intake pipe that i assume has been there since she got it and its had 200k put on it since then so i don't see that causing it. Ive checked the complete air intake for looseness and tightened everything up. Also checked the PVC elbows and could not find a leak there either, we did put it on a computer that a friend has and only real thing he could see looking at live data was a messed up bank 2 down stream sensor, i popped it out and it was definitely nasty, I noticed that 2 of the wires were worn bare on it so I replaced it, code stayed off about 2 days and came back, haven't had a chance to put it on the computer again though.

Any other idea's to check before she takes it in somewhere to have it checked out? it really has no loss of power or any noticeable problem other that the SES light.

Thanks.

 

[KWT2000]

there is a tech thread here about that it is most likely the elbow for the pcv line at the back of the intake manifold very common problem

 

[KWT2000]

here is the thread for that problem http://www.expeditionforum.com/f48/rough-idle-cel-p0171-p0174-some-simple-things-check-first-10745/

 

[77mud]

I checked those elbows, I didnt physically pull it off because it seemed everyone who did ripped it, but most people said you could feel the vacuum leak with it running and i did not, also I assume the air controls on it are controlled by vacuum? when i had a leak on my 97 F150 id loose vents and it would default to defrost but hers dont do that no matter how hard you accelerate.

 

[KWT2000]

the pcv elbow being bad will have no effect on the vents

 

[77mud]

okay, ill try to get it off the back of the intake and with out destroying an see if it is bad. Forgot to mention the radiator blew about the same time as the code cam on but they are not sure if it happened before during or after the radiator let go.

 

[KWT2000]

i would just feel it first and see if is soft rotten feeling

 

[77mud]

should it feel hard or should it have a soft feeling to it?

 

[Lane24]

Probably not your elbow. You would definatley notice it if it was your elbow. You wouldn't just be throwing codes, the truck would idle poorly. Just moving it around while idling, or putting your fingers over it would cause the engine to start running smooth.

So if you are not noticing a rough idle, did you check just check your MAF or actually clean it? That's where I would guess your code is coming from. Takes five minutes to do. Might as well give it a shot of cleaner. I'm sure you know how to do it, but if not, here's a copy/paste from the tech thread...


Just disconnect your air inlet tube ahead of the sensor, and spray some MAF cleaner through the screen at the little elements in the center of the sensor. Let it sit for 5 minutes or so...,give it another shot, let it sit for another 5 minutes, then start your engine. Some people just use electronics cleaner, but I recommend actual MAF cleaner from the auto parts store. You can also take the sensor right out and clean it that way too, but it's easiest to just spray it where it is. You can hold a rag or something behind it.

 

[77mud]

I wiped it down just to get some dust off it but that's it, ill pick some MAF Cleaner up and spray it down tomorrow if i get a chance. I felt around the elbow with it running again while the engine was cold so the heater hose's didn't burn me and felt nothing and the idle was not affected. the truck has no drive ability issues so I'm sure it is something simple somewhere.

 

[Bamfster]

Intake gaskets dry out and cause a vacuum leak ... very common for high mileage engines.

 

[Swetrid]

Intake gaskets dry out and cause a vacuum leak ... very common for high mileage engines.

Second that one, if you cant pcv hose leak it will be lower intake gaskets. Intake gaskets usually only show up when its cold out.

 

[77mud]

The engine itself has about 200k on it, but had a new intake put on it about a 100k miles ago due to a crack in it.

 

[77mud]

I picked up some MAF Cleaner today, when ever she gets off ill swing by and clean it. If that doesn't do it I guess she will have to take it somewhere, Im not feeling up to pulling the intake on it if that is the cause, these newer vehicles aren't anything like my old school engines that Im always tinkering with.

 

[77mud]

also i should add the Dealer did the engine swap, and the dealer did the cracked intake swap.

 

[77mud]

Okay... Cleaned the Maf Monday, she has drove the expo to work and back 2 times so prolly a 100+ miles and no SES light yet.

 

[hortonguy]

if you have acess to live data you can pull up both o2 sensors and watch them and use a can of carb cleaner and spray downn all vacume hoses and conections and the intake when you find the vacume leak the o2s will flat line lean and the engine idle will go up.

 

[77mud]

been over 500 miles put on it and no light. She had it Inspected today, and In NC you must pass what they call a Emission's test were the put it on the computer and it checks every thing. also pulls any code's that are on the car or pending, It passed that aswell. So pretty confident it was just a nasty MAF.

 

[mrazndead]

yes I had same deal. maf. thanks to lanes24 tutorial it saved me,

 

[Rosin]

Lane24 has it right. On my '99 4.6, the PCV hose completely rotted out, causing my engine to idle roughly and occasionally stall out when stopped. It did, however, cause a "System too lean" code. If you're getting a trouble code without any actual trouble, to me that seems like a problem with the sensor. Also, I'm just theorizing here; maybe somebody else can correct me. But couldn't "System too lean" also indicate a lack of adequate fuel flow, possibly caused by clogged injectors or a dirty filter? Filters are cheap and fairly easy to replace (make sure you depressurize the system first), and clogged injectors can sometimes be cleaned up by running a can of Seafoam or some other injector cleaner through the system.