Some Advice?

[Everdream]

Hello Forumsurfers!

I am helping a friend of mine work on a truck that he has. the truck has the following setup:
2000 Ford Explorer
4.0L
Auto Trans
4x4 (Yes)
Miles is ~160K

I did a full tune up when he first got it, including the Plugs, and wires and checking changing most of the fluids.

So, on to my actual questions:

My friends truck has a constant P0171/0174 Code triggered.
My friend had a CEL and the one code was P0171.
->
I have looked online and talked with people and learned most of the causes of these codes, upon looking I replaced the PCV Elbow and Valve (they were broken and loose) and Cleaned out the MAF sensor with MAF cleaner, Dried it out and reinstalled.
-> My friend Drove for about a month and now the codes are back, P0171/P0174 and there is a horrid howling noise from what seems to be the airbox, which comes and goes, It sounds like it is in or under the air box. I have checked and there is no leaks. (Paper test and sprayed a tiny bit of carb around the box opening and tube to see if it gets in. had no effect)

A co-worker told me to check the IAC, but I noticed that the IAC on this motor is on top of the engine, and not near the air box? or is it? This is the 4.0L with the triangle plastic cover over the throttle body.

I'd like to get these codes to go away and am looking for direction on what to check next, I sprayed fuel around the intake and checked the vac hoses and don't see anything. My friend is a disabled veteran and needs his truck in top shape for his daily living, as he he extremely limited in what he can do without it. Any help would be appreciated

 

[Darian Key]

My IAC was howling and unplugging it made it shut up so I replaced it. Try unplugging the IAC and see what happens while its running

 

[2000StreetRod]

vacuum reservoir tank?

From the description I suspect the engine is the SOHC V6 instead of the OHV V6 - 8th digit in VIN is E instead of X. There's a vacuum reservoir tank located below the air filter enclosure that is not visible. It's aft and above the body bolt circled below.

A semi-rigid vacuum hose connects the reservoir to the intake manifold. The hose may be broken or disconnected or the vacuum reservoir may be damaged (rusted) and leaking making the noise.

 

[koda2000]

in addition to doing the above checks, the SOHC engine is know for intake manifold leaks at the upper and lower intake manifold o-rings. these wouldn't make a noise, but it would trigger the P0171/P0174 codes. as the noise seems to be coming from below the air box, start by checking the vacuum ball and its hoses. to do this remove the passenger side plastic inner fender.

 

[colintrax]

He said it has a triangle cover over the TB that would mean it's the OHV.

OP search on here, there's a few threads on making your own smoker assuming you have a compressor. Makes finding vac leaks way easier.

 

[e200e]

I got rid of my code p0171 and I had a vaccum leak so I'm assuming you definitely have one. So you got the brake booster line, then pcv, and that vaccum plug thing. Make sure all the little red vac lines are hooked up just follow them. Also there is the egr tube to the intake manifold o-ring that seals that, make sure you check that because that was what my problem was and its pretty well hidden and easy to miss. check the little vac lines to the egr too like the green one and the yellow ones. Remove the air cleaner stuff and take the 4 bolts out for the throttle body and use that carb cleaner to clean the butterfly real good. The only other thing I can think of is if you really do need to replace that 02 sensor bank 1 sensor 1.

 

[koda2000]

I got rid of my code p0171 and I had a vaccum leak so I'm assuming you definitely have one. So you got the brake booster line, then pcv, and that vaccum plug thing. Make sure all the little red vac lines are hooked up just follow them. Also there is the egr tube to the intake manifold o-ring that seals that, make sure you check that because that was what my problem was and its pretty well hidden and easy to miss. check the little vac lines to the egr too like the green one and the yellow ones. Remove the air cleaner stuff and take the 4 bolts out for the throttle body and use that carb cleaner to clean the butterfly real good. The only other thing I can think of is if you really do need to replace that 02 sensor bank 1 sensor 1.

and if you're looking for vacuum leaks, don't forget the power brake booster. the P0171/174 codes mean that un-monitored air (un-monitored by the MAF) is entering the engine from somewhere and causing a lean condition (too much air and not enough fuel).

 

[Everdream]

http://gtcarlot.com/engines/Ford/Ranger/2000/692814/51030472.html Looks like this engine (OHV).

2000Streetrod: If that hose is broken, would that allow extra air into the intake? I figure if that is the case maybe this Vac thing is broken and letting in extra air, Its really loud on and off, but it is clearly next to or below the air box. (I was thinking IAC, but as far as I know that's the chrome one up under the triangle plastic cover and the truck has no idle or performance issues. Thanks for all the replies, I'm going to go through the lines best I can, I don't have many tools as I live in an apartment and they technically don't allow work to be done here.

 

[2000StreetRod]

open vacuum line

Any open vacuum line will allow unmetered air not measured by the MAF sensor into the intake manifold. That results in a lean condition at low engine speeds. Often the line gets accidently disconnected when working on something else like changing the spark plugs. The red arrow in the photo below identifies the connector and lower section of the hose.

Ignore the red upper hose since that is associated with my supercharger installation. Find the connector and then follow it downward to see if its still attached below to the vacuum bulb reservoir.

 

[Everdream]

So with this picture, would the bottom of the airbox normally be covering that area? the hose from the box would bolt into the blue (throttle body) I just want to make sure I'm in the right area for looking, i think this is making noise and poss. causing the vac leak.

 

[2000StreetRod]

near the A/C drier

The connector I marked with the red arrow should be near (maybe below) the A/C drier. There should be a mating connector with hose that runs upward to the intake manifold (I'm not familiar with the OHV V6). The lower connector hose runs down under the air filter enclosure and into the bulb vacuum reservoir.

 

[Everdream]

Thanks, will have a look today.

 

[Everdream]

I dont see anything abnormal under the air box, but the sound is like a foghorn now and again. I listened to the truck using a long screwdriver and I can not seem to pinpoint where the sound is from. I think I need to do a few tests, but I dont have the tools to do them, Anyone n the Tacoma area of WA maybe have some tools and able to help out let me know. This truck belongs to a disabled veteran friend of mine, and id like it running best it can.

 

[colintrax]

I don't believe there's any vacuum stuff under the OHV intake. Mine made some weird noises when stock. Whistling and whatnot

 

[lobo411]

Bad gaskets + loose bolts can make funny noises. The "blowing air over waxed paper wrapped around a comb" effect.