OK, so I've been a lurker for awhile now. I've used the forums to help diagnose and fix several problems with my 2001 Ford Ranger Edge 3.0L and I'm extremely appreciative. Normally I just look it up, get 'er done, and move on until the next disaster with Ol' Red kicks in.

This time, though, I need to ask specifically as I need help from people more experienced than I. I've looked over the "fuel bank 1 & 2 lean" threads, Googled until my Google goggles are fogged, and I still can't narrow her problem down.

As the thread title says, I have a 2001 Ford Ranger Edge 4x4 with a 3.0L NA engine that has thrown the infamous P0171 and P0174 combination codes, but also recently showed a confirmed the P0113 code (Intake Air Temperature Circuit High Input).

This all started a few months back when the truck would lurch at highway speeds between gears (whether this is irrelevant or not, I'm not sure). Eventually the truck started coughing and sputtering when pulling out of idle... this building to a crescendo one evening when the wife was out and it died on her completely when pulling out from a stop light in the middle of town. Then it started happening at highway speeds, actually dying out on me on the interstate. I was able to idle/gently tap the gas with my flashers on until I hit an offramp, coasted to a gas station, and got her towed home.

It idles rough at initial start up from cold, and I can get her a few miles up the road before she sputters and dies out on me again. It seems that once the truck is up to operating temperature and the pedal is pushed down after pulling out (or if trying to go slightly uphill), the truck begins sputtering and coughing with absolutely no power and the RPMs won't go over 1,500 or 2,000-ish most times. If you let off the gas to idle again, the truck will seem to regain consciousness for a moment then once you push at the gas again it does the same thing. It usually does this a few times before absolutely dying where she stands.

I've run a diagnostic tool on it and will post the results below. Not sure beyond the trim levels as to what would be considered relevant information, so I'll just put everything I wrote down. I took notes of the finding at both idle and at 2,500 RPMs. I'll post those findings below.

CODES: P0171, P0174, P0113

Short Term Fuel Trim (Bank 1): (Idle) -3.9 to 0.0 ........ (2500 RPM)-9.6 to -2.3
Short Term Fuel Trim (Bank 2): (About Same for Both as Above)
Long Term Fuel Trim (Bank 1): (Idle) 7.8 to 8.6 ........ (2500 RPM)5.5
Long Term Fuel Trim (Bank 2): (Idle) 9.4 .......... (2500 RPM)7.0 to 10.2
Fuel Trim Bank Sensor: (Idle) -2.3 to 0.8 ......... (2500 RPM) -5.5 to -3.1
MAF (LB/M): (Idle) 0.64 .......... (2500 RPM) 1.80
ABSLT (TPS): (Idle) 16.1 .......... (2500 RPM) 21.6

Fuel System 1 Closed Loop Status: Closed
Fuel System 2 Closed Loop Status: N/A
02 Voltage Bank Sensor: 0.200


So far, I have:
* Cleaned the throttle body out
* Cleaned the MAF Sensor twice
* Checked for the obvious vacuum leaks (hoses to sensors and main hose from MAF to TB, all seem good)
* Cleaned Idle Air Control Valve
* New fuel filter
* New fuel filler hose (old one was rusted out and leaking)
* New PCV valve and elbow
* New EGR Valve
* New Throttle Position Sensor


Given the codes and the resulting findings from running the fuel trims, what (in your opinions) are the most likely culprit?

Failing fuel pump? Sticky injectors? A vacuum leak I'm not seeing yet? I'm at a loss, the only garage in range I can get it to without it dying on me again is a joke of pure highway robbery, and I just got laid off after being outsourced. I need to fix my truck to get another reliable job and currently at a loss for funds to just throw parts at it.

What would you all check first and how? Any tips on how to narrow down the culprit so I can get Ol' Red back at it and me working again?

Thanks in advance, y'all. I would greatly appreciate any feedback on what you think the problem is!

Could be the fuel injectors, but the IAT code is a clue. Either the sensor could be bad/corroded, or the wiring has a short going to the sensor. You don't by any chance run a K&N filter do you? That can wreak havoc on the sensors in the intake.

The IAT sensor controls fuel mixture based on intake air temperature. It is located just next to the breather tube connection to the intake snorkel.

Thanks for the response!

No aftermarket air intake; all factory.

It appears the IAT is integrated into the MAF sensor on it. They all looked in good condition when I cleaned them, no visible corrosion and no visible damage to the connector (although we know visual is never 100%). Could the MAF have went out on me completely even though it looks good clean and has been cleaned?

Cheapest I've found the MAF sensor w/integrated IAT is about $60. I'd hate to dish out for a piercing multimeter or new MAF just to find out it isn't the problem, but I may have to in order to start eliminating possible culprits.

Are the injectors a pain to get out and clean? I've never performed that before.

Shouldn't be integrated. My 2000 isn't. The IAT sensor is in the far left of the picture.



The injectors are a bit of a pain, mostly because you have to pull the upper intake to get to them. Then the job is easy after that. Maybe 2 hours to remove and reinstall. But I don't expect that's your problem, since you have bank 1 and 2 codes for lean conditions.

So apparently the 2001+'s have the IAC integrated into the MAF sensor in a 6-pin set-up. My intake hose just has that opening blocked off where your IAC is.

So, I eliminated the 02 sensors just in case this morning. Sprayed some carb cleaner through a vacuum hose while I had my wife watch the O2 sensors' readings on the OBD II. Jumped accordingly.

I visually inspected every hose I possibly could reach to check for corrosion, warped, ripped, or flattened hoses. Nothing I could see. I ran the truck cold while spraying the carb cleaner around every opening, connection, hose, and gasket in, on, and around the intake. Brake booster hose, PCV, EGR, DPFE sensor, all around the throttle body connection, and as far back as I could around where the upper intake seam connects to the engine. No changes in RPM, up or down.

Not sure if chasing a vacuum leak will turn anything else up.

Could the IAC P0113 code be set off by anything other than the IAC going bad? Just wondering before I go looking for a new MAF sensor.

I guess the next step is checking the fuel pressure on the rail, but the cheapest decent-looking kit I've come across was still almost $50 for a tester.

Is there anything else beyond checking the fuel pressure and possibly trying a new MAF sensor that I should be looking for given the codes provided?

IAT vs. IAC

They would have the Intake Air Temperature (IAT) sensor integrated with the MAF - not the Idle Air Control (IAC) valve.

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Curent 2003 Ford Mustang Mach 1 owner - Build Thread for her: Logan's 2003 Mach 1

Former 2003 Ford Ranger owner - Build Thread for her: Project Budget Buster

If it's integrated you could get that code for a dying MAF. Try cleaning the wire first. If that doesn't work, replace it.

Ha! Truth. My bad, got in a rush and didn't even notice that. Yep, meant the IAT that's throwing that P0113 code.

Oddly, changed the IAC in it a few months back, too. lol

Just had a friend drop off their fuel pressure tester and going out there to hook it up and check that before dark. Will check back in with findings.

Hmm.

Everything looks good on the fuel pressure so far.

Hooked the pressure tester up to the valve, had the wife go to key ON position, and the pressure jumped up to about 43. Had her crank it over and the pressure jumped up to just over 65. I'm thinking I read those were both good numbers. Are there any other fuel pressure tests I should try while I have the tester borrowed?

I'm at a loss where to start next. I'd already cleaned the MAF and IAT sensor combo a couple times, so I guess I should get a new MAF and start there?

I think I've run out of tests to attempt. It's frustrating!

Test the MAF with a multimeter. There's a procedure somewhere on here.

Just came in from testing the MAF with my multimeter. Showing right under 12 volts solid. Went through a few walkthroughs on checking it out and everything turned out OK on it.

I can't for the life of me, however, find any information on testing that IAT -- or air charge sensor, I'm also searching for in Google -- or which wires are for it in that harness.

It will be pin #1 & #6 (Outermost).

#1 Wire = 20AWG Grey/Red
#6 Wire = 20AWG Grey

__________________
Curent 2003 Ford Mustang Mach 1 owner - Build Thread for her: Logan's 2003 Mach 1

Former 2003 Ford Ranger owner - Build Thread for her: Project Budget Buster

This is insane.

I still can't find any information on how to test voltage on the IAT sensor, but on my scan tool the intake temperature is reading correctly at 82 degrees (which is the temperature outside).

I'm completely out of ideas.

If I clear the codes and try driving it down the road again, I'm sure I'll get 3 or 4 miles again just like before and the engine start sputtering and dying when I try to give it gas again and I'll just have to have it towed back again.

Can anybody think of any test I haven't tried yet that can help trace down the culprit(s) here? I'm getting desperate!

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Thank you! I'll go test that now and check back! Greatly appreciated.

How should I go about testing those? Positive to X, negative to X, etc.? Sorry, I'm a bit new to multimeter testing as I just got one yesterday and I'm scared to death of frying something by accidentally putting a probe wrong.

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Could an exhaust leak in the muffler be causing the 3 codes by any chance? I've been seeing exhaust come up between the bed and cab since winter and looked under there and it seems there's a leak along the bottom of muffler seam. Just a pie in the sky idea as I'm stumped.

Just tested the IAT sensor wires. One showed 1.68 and the other showed 2.52, smoothly went up a few points on slight acceleration and smoothly went back down to hold. Intake temperature is showing 91 degrees on the code reader, which is about the temperature out there today.

Long Term Fuel Trim 1 is showing a steady 10.3 positive at idle and goes to 3.1 positive at 2500 RPM.

Long Term Fuel Trim 2 is showing a steady 11.7 positive at idle and goes to 6.3 positive at 2500 RPM.

Just got the upper intake pulled off. Upper gasket looks in pretty good condition; nothing to indicate a vacuum leak there.

And tested the fuel injectors with multimeter while down there.

All showing 12.0 Ohms resistence (give or take about .2 to the good or bad between the 6 of them).