Hello Fellow Rodheads . . . . and Lugnuts
Oct 2007 -
My Dad’s 1999 Ford E150 Econoline (Conversion) Van 5.4 liter V8 160k miles.

Current codes- 171, 401 - but past codes a few days ago were 171, 174.
P0171 System too Lean (Bank 1)
P0174 System too Lean (Bank 2)
P0401 Exhaust Gas Recirculation Flow Insufficient Detected <O:p></O:p>

The change in codes yesterday was when I found the PCV valve was OFF the right side valve cover. I checked codes immediately and found they were now 401 (EGR) and 171. (I think it was 171 rather than 174 but it was not both of them- which may be significant since the PCV valve is mounted on the right side valve cover).

Hx- History. A few weeks prior I tried to start the van- would start but idle down and die. Tried 10 times. Went inside – made a phone call- back in 10 minutes- the van started and ran fine. I read there are several things that can cuase this - Throttle Positioning Sensor, PCM, etc. Temperatures have been in 60s and 70s.

Over some days, the idle got rough- up and down but otherwise ran fine.
A very good- trustworthy mechanic tested some things – and found Fuel Pressure was low- around 30 psi- should be 35-50 psi. Replaced fuel pump and screen – MIL- light came on that night ! w/ 171 & 174 codes. Low fuel pressure can cause the 171 – 174 codes.
After perusing these great online help boards found several possible causes but it is definitely it is NOT the O2 sensors- they are just the messengers.

Mechanic was puzzled- Ford dealer looked for an hour while they disengaged the recalled Cruise Control switch- and they said- vacuum leak- but need more time. <O:p</O:p

Then I crawled under the doghouse and found . . . . PCV Valve was off the (right side) valve cover. Just resting on top. Not sure when that happened - but it was NOT clogged and there is vacuum- but I replaced it anyway.
Drove up the road to AutoZone- checked codes to find NOW- 401, 171. !

I sprayed Ether and Carb cleaner all around engine, intake, manifold, PCV, EGR – basically whole engine got sprayed - and no change in idling.

MAF- Mass Air Flow meter/ sensor – ($225 @ Ford- 160 elsewhere) Today I found it, removed and sprayed MAF cleaner all over w/ very little if any visual change. One of the 2 wires is clean and shiny, the 2<SUP>nd</SUP> one is dark and seems to have some build up of debris.

Yesterday Guy at Ford showed me a new one- broke the seal on the box and it of course was all clean and shiny but I didn’t look real close at the wires.
I will drive and go through a bunch of ignition start/ stops and clear codes and see what I get.
So now- w/ 401 EGR error code - I am reading could be EGR valve ($62), DPFE (likely), and a few other things and of course I don’t want to replace the MAF at $160 unless I am sure it is the culprit.

Replace Valve covers- also read here about some new valve covers w/ baffles or something – and replacing them and gaskets - yikes- don’t want to do all that.
So- any feedback much appreciated. thanks Lugnut 2008

Also any other books ? the Haynes books are lousy as far as showing pics and diagrams of where all these components are located on the engine- and w/ this Van- it is real difficult to get at anything.
Any other good sources for books and photos and diagrams of the Ford 5.4 l V8.
This version I believe was manufactured in <?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com[img] /><st1:country-region w:st=[/img]<ST1:place w:st="on">Canada</ST1:place></st1:country-region> and has some different components. Thanks for your help and sorry for my lengthy intro.
</O:pLugnut2008 Christopher

 

Hey Lugnut, Welcome to the forum.
You are on the right track. I would check the PCV hose elbows, especially where it goes to the rear of the intake manifold. These get soft and crack causing a vacuum leak.
The P0401 is usually either a bad sensor of the EGR ports are clogged in the intake manifold. I'd doubt that the MAF is bad or it would run bad usually.

 

Now codes 401 and 171 / 174
Thanks LxMan1 for info and reply.
Took no more than 10-15 miles to get the light back- and the codes.
I read that 401 (EGR flow restricted) can cause 171 - 174 codes- runing too lean banks 1 & 2.
Not sure why the 401 took 3-4 weeks to show up- and happened AFTER I found the PCV valve was disconnected- but I do have strong vacuum by touch.

I was thinking on trying the DPFE (Differential Pressure Feedback system) thing which costs about $56. Then maybe the EGR valve which is another $62.
But first I have to trace ALL the hoses around the EGR, pull them off and check for damage, cracks and blockage.
QUESTION: Another issue with the 401 code is possible blocked EGR ports in the intake manifold. What does this entail for fixing? I mean if this is the intake manifold and Emission Gas Recirculation ports, what could be cuasing blockage?
I'll post back w/ results.
Just weird to have the 401 (EGR) code appear after 3-4 weeks with codes 171 & 174 and after finding the PCV valve disconnected.
Thanks.

 

MAF Mass Air Flow sensor cleaned too.
Also, I removed the Mass Air Flow sensor device which is inside the air intake duct right behind the air filter. I bought a can of MAF cleaner for about $6, a little more than carb cleaner but recommened becuase this stuff does not leave any residue.

This device has a large bore where the air enters. Same width as the intake hose.
There is a bar that goes across this opening with 2 wires. One was shiny and clean and the other looked dark as if something has burned on it. The cleaner did nothing. None of the dark gunk was dissolved after spraying half a can all over this thing. The MAF costs $238 at Ford and $170 or so at the parts store.
Ford has a buletin out about this thing that it can get "contaminated". What?

Everyone has said I might get a short reprieve after cleaning but the trouble comes back. And since this is an electronic device, no returns allowed.
It applies heat to these wires and checks the temperature to see how much the wires have cooled and then calculate how much fuel to apply.

Farther down the intake hose is another sensor which I believe to be the IAT. (Intake Air Temperature sensor).

 

Sorry if it was covered but I didn't have time to read all of the thread, an easy way to find a leak in the PCV lines or anywhere else is to take some starter fluid and spray it on the joints, if the idle picks up you just found the vacuum leak. I recently had my IAC leaking, when I replaced it I must not have tightened the bolts enough and the original gasket was used. Sure enough, a little starter fluid on the IAC mounting surface and the idle came up on mine, I also had 171. It is pretty rare for the MAF to go bad unless you ran an over oiled after market air filter or contaminated it some other way. Also with a vacuum leak there is almost always a loud hiss created that is very noticeable with the hood open.

 

Solution: Ford E150 Codes 171 & 174 and 401
Thanks all for your suggestions.
While waiting for my mechanic to look at the van again- I started getting skips and misses- running REALLY rough- and bucking all the way, though I could get to highway speed- 65, 70, 80 mph.
It showed a code indicating Misfire Cylinder 8.
It sure was. Never saw a car run so rough w/ 1 cylinder missing.
Replaced the plug andcleaned the boot- this engine has COP plugs-
that is Coil on Plug arrangement.
Fixed it- and ran fine.
But while I was messing around with the doghouse off the engine- testing the electrical connectors, voltage and resistance on the DPFE, EGR- I traced a couple hoses around to the right side of the engine and found 1 of the 3 hoses that run down the right side of the engine compartment (and I assume to the tank) was disconnected.
I tested it- held a finger over it and guess what- a good vacuum pulling in- hence my vacuum leak. !
The PCV valve (I replaced it for 5 bucks anyway) and the PCV hose was fine.
I even tore off this thick spongy insulation that was wrapped around it.

So my waste was- on suggestion of my good mechanic, getting the injectors cleaned- a waste of $69- and having Ford dealer look at it for an hour- ! to tell me I have a vacuum leak. F-ing Duh, Lugnut brains!

Seems a dealer- very familiar w/ the whole damn Van- should have been able to trace every hose all over the engine compartment to checkj for anything disconnected- if not to check further for any leaks.

Sidenote- have my Subaru Forester throwing codes 400 and 440- EGR and EVAP.
there is some leak in the EVAP recirculation from the filler tube. So I took off the plastic cover in the rear-right whee well where the gas- filler tube is and poked around.
The tube is all corroded (1998 car) and the 3 hoses that connect to the charcoal cannister and up to the intake (I think that is where the other 2 go) were ALL corroded and the valve was completely all apart- so major leaks.
The new filler tube $117 - and the valve that mounts on it - $71 plus 11 dollar gasket.
Likely an hour or so w/ the mechanic on Monday.

I was the one that found BOTH problems- not my mechanics- or the Ford or Subaru dealers ! Subaru did perform a pressure test (done w/ smoke I understand) pressurizing the tank and other hoses- which did not hold the pressure- indicating the leak- somewhere.
Now I just have to figure out where the three hoses attach- I never made a diagram or gave attention when I pulled them all apart -
Cars- love em- or get a horse. !