Ford Techs please.

[Instigator]

'99 Ranger XLT 4 wh dr 4.0 (single cam) V-6 w/check engine light on.

Codes are:

DTC P0171
System Too Lean
(Bank 1)

and

DTC P0174
System Too Lean
(Bank 2)


The "experts" :eek: :p :o :D at Auto Zone said:

It's one or more of the four different O2 sensors, the mass air flow sensor or a fuel pump :eek:
Gee, thanks for narrowing it down for me!

Any suggestions guys? About 104K runs like a top and light just came on this morning. I have my own code reader here but am sure it will say same thing.
Can it be lean enough to do damage until I figure out whats going on??

Oh yeah, the "expert" at the parts store was nice enough to print off all the possible defective parts for me.

With both side being lean I'm gonna guess MAS?

As always, thanx a million guys!
Gary

[The Big Al]

Test fuel pressure!

Fuel pump or pressure regulator seems to be the problem.

By the year it's almost time for new electric pump!


Auto Zone loves selling those O2 Sensors!

[The Big Al]

MASS air flow sensor has a major fault code. It has a self test.

I don't see the OB2 missing it.

Al

[Scream And Fly]

Gary, I did find this:

Some vehicles may exhibit a check engine light on and lean Diagnostic Trouble Codes (DTC's) P0171/P0174 (system too lean bank 1 or 2) stored in memory.

Do not replace PCM (Powertrain Control Module), MAF (Mass Air Flow), or HEGOs (Heated Oxygen Sensors), as these parts are not the root cause of the lean codes conditions described.

These conditions may be caused by a loose fitting on the fuel pressure regulator vacuum line on the intake manifold end and/or leaking isolator bolts/port gaskets in the lower to upper intake manifold mounting area. This condition is sometimes intermittent and may not be apparent on a warmed-up engine.

[The Big Al]

Gary, I did find this:



These conditions may be caused by a loose fitting on the fuel pressure regulator vacuum line on the intake manifold end and/or leaking isolator bolts/port gaskets in the lower to upper intake manifold mounting area. This condition is sometimes intermittent and may not be apparent on a warmed-up engine.



I love me!!!

[Instigator]

I freagin love this site! Car questions, stereo questions ...it just doesn't matter!

Greg, where'd you find that?? Will trouble shoot this weekend.

Al, Thank You Sir!

P.S., Greg I'm thinking I need some pixs of my boat runnin. Think you can help a brother out?

[Scream And Fly]

Gary, I Googled it and came across that - I'll see if I can find where I got it (I should have bookmarked it).

Photos are no problem at all - sounds like a great idea!

Greg

[Instigator]

Will you and Maureen have shirts and stickers there??

Thats all I needed to know about your Ford info. Was just curious where the info came from.

[Scream And Fly]

Unfortunately, it looks like I won't be at the River Ranch. It's looking like I'll have to cover the OSS race in Destin that weekend. Maureen will be at the RR though, and she'll have shirts and goodies.

I still may be able to make it to the River Ranch (I hope), but we'll see...

Greg

[Instigator]

Unfortunately, it looks like I won't be at the River Ranch. It's looking like I'll have to cover the OSS race in Destin that weekend. Maureen will be at the RR though, and she'll have shirts and goodies.

I still may be able to make it to the River Ranch (I hope), but we'll see...

Greg
Well, I sure hope you can make it. Talked to my buddy Mike (msg11) from Ohio w/the 300X Mirage and he's towing down for it and probably stay with us for a week or so after. May sneak to the Keys while he's here.
Tonys coming down too but flying his plane down.

[Scream And Fly]

Believe me, I want to go - badly. The River Ranch is an amazing event, and this one will be huge. I'm hoping...

[Instigator]

an amazing event, and this one will be huge. I'm hoping...
I agree.
The makings of one of the really special events. Great guys running the show.
Gary

[SteveO]

I had those codes on a 97 4.0 ranger a few years ago. Turned out to be an intake leak.

[Instigator]

I had those codes on a 97 4.0 ranger a few years ago. Turned out to be an intake leak.
Guess I know where to look.

[delawarerick]

Mass air sensor on air horn has to star type screws mark if not marked and count turns out lift out sensor and see if there is any dust dirt, a little will cause the light to be on. They make a cleaner spray it and the base. put the screw back in disconnect battery 45 minutes connect and see if light returns. Rick
if that does not work take to cold beers and put tape over the light:D

[sho305]

Be careful of that fuel regulator. I had an older one with the 2.9, so maybe new ones are different, but the regulator vacuum line was hooked in with the brake booster. It went bad and filled the booster with gas and flooded the motor out in the near cylinders. Once I figured out why it hardly ran I found out it had trashed the booster too and that was a pain to change out.

Yeah, the free read is nice but I noticed that after a little while of doing that Autozone's policy changed and they started to push possible parts really hard. Most of the time an O2 sensor will trigger the light after it is warmed up in part throttle driving.

[Instigator]

I unpluged the battery @ work.
Light went out and put about 100 mls on it since and it's still out.
We'll see.

[SteveO]

I kept a 7/16 wrench in the glove box for 6 mo to disconnect the battery and turn off that check engine light.

[sho305]

You can change the plugs, looking at them might help tell you what it is doing. Most of the time if the intake leaks underneath the oil makes a lot of carbon....if it just shows light color it is lean...if they are all the same maybe a sensor.

[Rickracer]

They don't go bad, they get dirty. If it's one of the ones that's held in by two screws, take them out, (don't lose the O-ring), spray off the two resistors (little wires with a lump in the middle), blow them dry, re-install. If one of the wires looks dirty before cleaning, it's practically a guarantee the idle will improve, and the MIL will stay off. :cool:

[Instigator]

They don't go bad, they get dirty. If it's one of the ones that's held in by two screws, take them out, (don't lose the O-ring), spray off the two resistors (little wires with a lump in the middle), blow them dry, re-install. If one of the wires looks dirty before cleaning, it's practically a guarantee the idle will improve, and the MIL will stay off. :cool:
Thanx Rick! It does idle rough every once in a while.

Sho, planning on doing plugs anyhow. 100K and I'm sure orig. plugs :eek:

Steve, used to do that in my Burb ;)

[bigbore]

i'm with rickracer,either the mass air or the injectors,or it's possible there's a gasket leak,i'd lean twards th mass air itself or,injectors (dirty or not pulsing properly)getting to that point with miles.:cool:

[Rickracer]

....with a mechanics stethoscope, (or a piece of vacuum hose held to you ear), but with the plastic intakes, sometimes turns and transitions inside the manifold make a tearing sound sorta like a vacuum leak. Carb cleaner with the extended nozzle in it is a good tool for finding vacuum leaks on EFI vehicles. Wouldn't hurt to check for that too, but definitely look at the MAF first. :cool:

[sho305]

I did the mass air sensors on two cars this summer. Those you just took out and sprayed the wire with contact cleaner. One was really black and that car ran better without a doubt. The other one was a little gray and it didn't make much difference. The dirty one had 60K miles and the cleaner one 80K. Both have good air boxes and filters are sealed in good.

100K? Yeah those plugs are done, even the triple platinum the fords like. Make sure you put the right plugs back in, I only use the same motocraft in fords now after having problems with 4.6s. Bosch platinum plugs actually blew apart in a 4.6 F150 when they were not shorting down the plug.

[Rickracer]

...I use Autolite Double Platinums, and only Bosch wires, Motorcraft plugs are made by Autolite anyway. :cool:

[Instigator]

98K on it from a used car lot so who knows about maint. or lack there of. They, of course knew nothing ;)
Have done oil change and trans fluid/filter.
Checked air filter (and cleaned) and it was O.K.
Plugs and wires next.

Here's a strange one too (if it's bad don't tell me), the intake whistles at idle.
I mean bad! It stops at anything above idle. Also stops if you pull off intake hose going to filter??

[Rickracer]

Here's a strange one too (if it's bad don't tell me), the intake whistles at idle.
It's not bad, mostly just annoying, there may be a TSB on it. Shoot me the info on it to rick@rickracers.com and I'll check for ya on Monday. :cool:

[77SLEEKCRAFT]

How did you make out fixing the ranger ? I work at a ford dealer in northern Illinois and we see alot of upper intake manifold "0" ring seals that shrink due to colder ambient temps. Causing vacuum leaks resulting in a lean condition.

[Instigator]

Changed plugs today.
OEM gap spec is .054"

Plugs removed ranged from .075" to .085"!! A testiment to the power of Fords igniiton.

MAS sensor is mounted w/2 "tamper proof" torx screws. Tamper proof, not Gator proof though ;)
Looked fine but cleaned anyhow.

Several hundred miles since un-hooking battery and still no light :D

Idle and low speed is now much improved and hope to see increse in mileage as well.

[electricjohn]

Might have had a little water in you gas. That will throw that code too.

[Instigator]

Might have had a little water in you gas. That will throw that code too.
It did it again and started to idle rough again when I noticed my temperature gauge was barely moving.
Fixed that, re-set codes and is running fine again.
Not sure if it has been running cold entire time or not but just caught it and I know that will throw the system of too.
Thanks for all your help guys!
Gary

[1outlaw]

OK i didnt read everyones responces....But i did read your complaint....The fix is to replace the upper and lower intake manifold o-rings.....Now as a preventitive maintence.Pull the MAF sensor our of the housing it will be bolted in with 2 T-20 torx screws and 1 may be painted over just use small pliers to loosen it. Now look inside you will see 2 wires clean real well with Carb clean and reinstall....99.9% of the time this will take care of the prob..In a rare case clogged injectors will cause this code but it usually sets a misfire code as well...Do what i have told you and i can almost guarantee it will be fixed.
Im a ASE master L1 technian and own a shop...If you want PM me and i will give you my # and we can talk more.

Good luck
Jason

[randy 77zt]

i worked as a ford dealer tech-we used to hook the ford code reader and watch the signals off of the front 02 sensors and the short term fuel pids while spraying carb spray around the intake -you could find the leak.most ford dealer stock the oring for the intake.not a hard job.i used brake cleaner on the gaskit surfaces to clean them up.be carefull tighting some parts up-plastic will crack.

[Instigator]

thanx guys!
Already cleaned the MAF sensor w/no change.
Light is back on and staying on.
Seems to be running pretty good but am now leaning towards an intake leak as suggested.
Will check this weekend time permitting.
Thanx again guys!!
Gary

[Riverratt]

did you try different coils? I have some of the high output coils for drag racing if you need some.:D

[Instigator]

did you try different coils? I have some of the high output coils for drag racing if you need some.:D
killin me :o
Never thought of that though???Hummhhhh ;)

[delawarerick]

Are those the type that bolt onto the valve covers:eek: Rick

[stvhelm]

I had the same problem with both the p0171 and p0174 codes in both my 96 5.8L bronco and my 99 and 00 3.8L ford windstars. Its not gasket leaks or bad 02 sensors. I went through the same crap with my long gone 99 windstar. I changed all the ox sensors and did the intake gasket and some other stuff. one mechanic said stop running 87. the ethenol is f'n it up. ever since I ran the premium my light never came back on on either car. a couple of times I tried switching back to 87 and eventually the light comes back on. also never unhook the battery to reset the ecm. It will idle badly when its warm. it also states this in the sevice book.
the best site for car repair is flatratetech.com you see factory techs posting their. Im sure this topic has been covered numerous times as well.
good luck

[Instigator]

I had the same problem with both the p0171 and p0174 codes in both my 96 5.8L bronco and my 99 and 00 3.8L ford windstars. Its not gasket leaks or bad 02 sensors. I went through the same crap with my long gone 99 windstar. I changed all the ox sensors and did the intake gasket and some other stuff. one mechanic said stop running 87. the ethenol is f'n it up. ever since I ran the premium my light never came back on on either car. a couple of times I tried switching back to 87 and eventually the light comes back on. also never unhook the battery to reset the ecm. It will idle badly when its warm. it also states this in the sevice book.
the best site for car repair is flatratetech.com you see factory techs posting their. Im sure this topic has been covered numerous times as well.
good luck
Thanx!
Gary

And Rick, I think those coils are mounted with drywall screws. A college edumacation learns U things like that :p

[Surface_cutn]

The problem is actually the intake manifold upper half (Plentum) O-Rings become Rock hard. When the engine is cold and/or your moving down the road it draws in air causing it to kick out lean codes. Running it warm and trying to test for a vacume leak it will test ok. Swells enough to keep it masked. A smoke machine cold would show the problem. Mass Air flow sensor is the common diagnosis and then after resetting the fuel trim a test drive shows ok.. Tech thinks he's got it but as soon as the computers fuel map corrections become out of range, could take days the light comes back on. O-rings are absolutly for sure the problem. It's pretty easy to do too..

I manage a shop with 35 years experiance and my specialty is on-board computer, electrical and fuel systems. I've seen many, many of these..

As far as a Windstar goes it has it's own problems a little different but in the same area. Technical service buliten says to replace the plentum bolts and the O-rings, front valve cover if there isn't a hole it in the PCV baffle plate so as to drain the oil back into the motor when it gets caught in there. Also replace some of the vacume tube assy's. Then make sure the computer has the newest software in it. The fix is one of the vacume tube assy. I believe it is the fuel pressure regulator tube/ PCV hose. It becomes impregnated with oil and you really don't notice it when looking for a problem. Pull it off and you'll see it on the inside. Odd ball looking hose with very large end on it connecting to the intake. It has a big price too.

[gotboostedvr6]

i dont feel like reading the replys but check the intake for leaks and brush off the maf very very carefully

[RONNIE]

opriginal post is pretty old

[Instigator]

opriginal post is pretty old

sold that thing almost a yr ago.

Several stated as surface-cutin did though.

Thanks again for everyones help.

[stvhelm]

yeah and my engine light came on again about a month later:nonod:

[sho305]

My little ford with the bad trans is still going good with the cooler and additives, but I think a wheel bearing is talking to me and they press them in so I can't do it. Waiting for it to get louder, lol. I have no idea what car I will buy next.