Ya so I took my ranger to a local garage yesterday and they had a mechanic run it on his computer to check sensors and see if he can give any ideas as to it running lean. they were kind of confused about a 302 under the hood and admitted they don't get involved in this area. I asked what the maf sensor reading was, customers aren't allowed in service bay there. they told me the reading was 131 barometric pressure and he feels the sensor that runs egr might be making it run lean, however its actually running rich, they could smell gassy exhaust if that sounds right. the mechanic at work says the maf reading should be 153 due to the altitude of about 1080 ft above sea level. I took a gamble and bought a new, refurbed , maf sensor from summit. I don't have a chart to know if he is right but what the guy at work says makes more sense, if maf tells ecu the air is thinner its going to give less fuel and the other sensors will tell it its not right...anyone with knowledge on this please chime in

 

How are the plugs, no misfires noticed right? If it's rich and saying it's lean the 02s are seeing oxygen in the exhaust, in the case of misfires it's a never ending cycle, the o2 sees air adds fuel to compensate but still sees air so adds in more fuel. I'd suspect possible vacuum leak misgapped plugs, or a lazy o2. What set up are you running, is it a distributor setup or the Explorer coil pack, or are you something even different from that.

 

What bank, bank 1 bank 2 or both? Another thing to look at is an exhaust leak, or fuel pressure. If the pressure is low it'll throw lean codes. If you run out of gas they could throw a lean code also.

 

If you smell gasoline at exhaust then Cats are not working, Cats burn up unburned(rich) fuel mix, one of the reasons they are there.

You know your V8 is running Lean because..................???

Engine is pinging/knocking under acceleration?
Engine is running warmer than usual?
These are signs of actual Lean running

If it is only Lean codes then share them, OBD codes are written in english but are translated from computerese, so not to be taken literally
i.e. a Lean code does NOT mean engine is running Lean, it means computer's calculation for 0 Fuel trim is not being confirmed by O2 sensor feedback.
Computer is having to add more fuel than calculated to get correct feedback from O2 sensor so it sets a Lean code to let driver know that calculations are off for some reason.
At no time was engine actually running Lean

Most lean codes are from air leaks, unreported air is getting into the intake so computers calculations are off
Low fuel pressure will cause Lean codes, computer expects 35psi and bases calculations on that, if pressure is actually 20psi then computer has to add more fuel, Lean code set

 

Yes I'm aware of these things, the mechanic at work says that any efi engine he has plugged into the maf sensor gives a barometric reading of 153. mine is giving 130 so its thinking its at a much higher elevation and needs less fuel. I don't hardly ever hear any misfires. the codes are 0171 and 0174 or both sides. I do have a 02 that is sluggish but they both show that they are cycling. according to both mechanics the short term fuel trims are good but the long term are really bad? the one time I checked fuel pressure with a tester it was at 35 psi. I don't really know its running lean..the trouble code says its lean but it may not be. as for vaccum leaks it idles really smooth once it gets over the first 30 seconds or so. I just ordered a maf sensor from summit. one thing I will add, ive got the cold air intake air filter mounted where air box would be and its from the 3.0 motor but I was told that isn't important..thanks for input

 

By the way..i don't hear any pinging under acceleration

 

You know your rough idle for the first 30 seconds sounds like your IAC might be getting gummy, if it happens to stick it can cause lean codes depending on where the IAC takes its air in from, but you'd notice weird corky idle issues everyonce in a while, have you checked the pcv by chance? I mean really your best bet at this point would be to get your hands on a smoke machine and smoke the intake to look for an air leak. But I guess I'm getting ahead of you, I guess it's just what I'd do if the maf don't fix it. What manifolds BTW? Is the egr active or deleted?

 

Mine still has a few issues with the computer system, I'm looking for someone that can tune oem computers right now. I took the whole setup out of a 98 mountaineer, put a WC t5 in it deleted the evap, and egr. Now I have codes for all the shift solenoids, and I run around in limp mode most of the time. I'm just having a hard time justifying spending the amount of money counts customs wants on something I can't even see. But it seems like all the aftermarket ecus want you to change over to Chevy style sensors. Which I might end up doing and tuning it myself at that point, I learned all this **** in college, but working at a meineke really don't keep me up with all that.

 

Lean Codes are for computer calculations being off, not actual engine running Lean

Yes, could be MAF sensor if both banks have codes

I only use Grams per second(g/s) to test MAF sensors, so not sure what 130 or 150 would mean
Barometric pressure is a calculation done by computer, system has no air pressure sensor.
MAF should read engine displacement at idle in g/s
5.0l should read 4.8-5.2g/s
4.0l 3.8-4.2g/s
3.0l 2.8-3.2g/s
ect....
The Higher elevation the lower it would read because air has less weight, and a gram is a weight measurement
14.7:1 air:fuel ratio is a weight ratio, 14.7 grams of air requires 1 grams of gasoline to get best burn

 

I get what ur saying, the mechanic uses a laptop with program for testing efi on most vehicles. but here is the fun part. maf sensor was here when I got home so I disconnected battery as he said I should so computer relearns. put new sensor on. he said it takes 5 min to reset kam. I fired her up and she went into low idle, maybe 500 rpm tops, then tried to stall so I shut her off, several starts later she would run on her own but I could feel a mild thump like a misfire, it went away after awhile. I drove it around block and it was ok but not real smooth. the intake is stock that came on it. egr is active, the motor is set up like factory, all sensors working, maybe not right but working. that iac is a thought. the exhaust is factory to cats..the its home made..i cut flange off and put adaptor on each cat..have 2 glass packs and pipes near rear diff with downturns. I wanted it to look factory and be emission legal only did not know dumb law that says cant have a motor factory didn't use, hence 5.0. I did the first 20 min warm up, now to cool for hr, then retry. kind of interesting u say maf doesn't say barometric reading cause on his laptop it shows maf and says 131..i have no clue what it is about? I understand barometric pressure stuff but not maf sensors. I figure I'm doing ok because it does run and I'm no mechanic..i paint cars, but I got it in there and ive fixed other issues. the bitch of this is it was running and idle started to drop and she ran like crap but no engine code, I'm hoping for it to talk to me , ya know..thanks for your advice and input

 

Oh, I do get weird corky idle issues every once in awhile, ill drive it nearly 16 miles to work, stop for coffee, start it up and try to go and it says not so fast, hit gas and it runs bad, I let it idle for a minute, rev it up a lil and if it revs decent, maybe 1500 to 2000 rpm and then it will be fine, or maybe not. does this from time to time so maybe I could pull and clean iac?

 

If engine was cold and it was idling at 500 then there are other issues.

ECT(engine coolant temp) sensor tells computer when to Choke the engine, high idle, rich fuel mix and advanced spark timing, same as a carb did with choke plate.

If ECT sensor is telling computer engine is at 120degF when it is really 60degF then you would get a cold start that would barely run, no Choke.
This wouldn't set a code because computer "thinks" you are just restarting the engine after shutting if off for a few minutes.


For $25 you can buy a Bluetooth OBD2 reader, it plugs into OBD port on truck and connects wirelessly to your Smart Phone or tablet via Bluetooth
Then you can do what mechanic did, read codes or Live Data while driving.
And it will work on ANY VEHICLE sold in North American from 1995 and up, so not a Ford or Ranger thing.

So you can see ECT temp, IAT temp, MAF g/s, and a whole host of other data

Ford did away with MAP(manifold absolute pressure) sensors in late '80's, early '90's in favor of MAF sensors.
So there was no Barometer sensor any more.
Ford did add the DPFE(differential pressure feed back) sensor for the EGR system in the mid-'90s and that did sample Barometric pressure prior to start up of the engine.
But it's not really needed with MAF system since lighter air, elevation, is compensated for by the MAF setup, heated wire cools off less in lighter air.
This doesn't work for elevation pressure changes after startup, only with key on engine off can it read local pressure.
So the barometric pressure you see is from a few sensors, MAF and Throttle position sensor, and RPM(crank sensor) and it is a "best guess" by computer, but as said not really needed.

 

I'm going to look for that scanner, I'm pretty sure the coolant temp Sen I hav in it is from 3.0..the one I bought brand new for 5.0 didn't give a signal? Someone on another forum said they put the one from old motor in new motor so I tried it. I cleaned my iac motor, that helped some. My neighbor thinks the mechanic here at work is wrong and thinks I'm getting better advice on here and maybe take it to custom tune shop, I'm going to see if I can find that scanner u mentioned..thanks for help

 

There are TWO coolant temp sensors, well one is a SENDER not a sensor

ECT sensor will always have 2 wires, it is ONLY used by the computer

ECT Sender can have 1 wire or 2 wires, it is ONLY used by the dash board temp gauge.

If both have 2 wires then turn on the key and look at the dash temp gauge, should be at cold(assuming cold engine, lol)
Unplug one of the ECT units at a time
When gauge drops below cold or goes to HOT then you found the Sender for dash board gauge, other one is for computer


The Bluetooth OBD2 readers are easy to find, but you also need the APP for the phone or tablet, the free ones work fine, but you can also buy other APPS for more details, start with free then decide if you need more.

 

Ok the ect I changed was the dash gauge one, for some reason the 5.0 one wouldn't work with dash so I put one for 3.0 in. ill check the other...where ever it may be..lol. I also am looking into the pdfe sensor..read that it can cause a lean condition if not working. when I had it at garage sat the mechanic said that could be issue? found out its pretty much a map sensor. thanks again

 

oh, I did your test for vacuum leak, I ran engine for about 15 min, then unplugged the iac..the idle dropped to about 400 rpm, it didn't stall but stayed low. I plugged it back in and took it for a drive, if I remember you said that's good

 

Yes if idle dropped below 600 then no vacuum leaks.
When you plugged IAC valve back in idle should have come up to 700 or so, right?

DPFE sensor would be a long shot, while it does get local air pressure at key on, after that it's only use if for EGR system.
If it was used specifically for air "weight", barometric pressure, then if you drove from sea level to 4,000ft without shutting off the engine you would be blowing black smoke at the top, lol, well not really but engine wouldn't run too well.
MAF sensor is used for that, no actual pressure measurement, it can just detect lighter air, less oxygen molecules, because heated wire doesn't cool down as much.

All fuel injected engines must have an ECT sensor, used only by the computer, not an option, a must have, or no Choke, so no start and no run, at temps below 60degF

 

I'm going to put a new temp sensor in for start, then a new pdfe for possible lean condition....

 

DPFE sensor, and they usually need to be replaced every 80k miles or so any way, but they show EGR codes when failing

 

I read the dpfe can cause lean condition if it is going bad but not shot. One mechanic said he thought that could be it

 

A failing DPFE sensor could cause computer to open EGR valve too much, which could cause Lean codes, long shot but not a no shot

 

Ya that's what I read on a site online about dpfe, the sensor is a metal one and most of the sites said the plastic ones are better? the ect is old one I didn't change but will this weekend. she seems to have 2 issues, rough idle at start up, and running lean and I'm thinking the ect is part of start up like you said, I didn't realize how important that sensor is. but I do now..thanks for your help

 

Yes Plastic DPFE seems to last longer

DPFE sensor has 2 hoses connected to the exhaust system, usually EGR tube.

When you burn gasoline with air(oxygen) one of the by products of this burning is H2O(water).
This is why exhaust systems rust from the inside out, and why tail pipes drip water out

So the DPFE sensor hoses have water vapor in them.
When you turn off the engine the DPFE sensor and hoses cool down faster than exhaust system, this causes water vapor to condense in the hoses and in the DPFE.
Same as water vapor condenses on a cold glass of beer on a warm day, lol.

This water ruins the DPFE sensor over time, the metal sensors seem to cool faster than the plastic ones so plastic gets less water vapor condensing.

 

I had a metal DPFE sensor, it was probably in there since the truck was new (17 years)
I replaced it with the plastic one and I took the old one apart.
The water corroded the metal behind the internal seals, like a dog digging underneath a fence.
Once the water reached the circuit board, it shorted out, there was rust and this white powdery build up all over the board.

The sensors in the plastic ones are solid state now too.

 

Ok so new dpfe is in and still got a lean on both banks code. also the ect is in and she still starts a lil sluggish. the guy..fordmiller asked about coil packs or dist. its coil packs, one new because plug seemed loose so I bought one. I do have an exhaust leak, very small one right after cats. you can hear it a little at idle. I do wonder if that could be sucking in air that messes with the 02 but it would only be pass side. unless its got a pinhole somewhere else. when I drive it she run ok but you can feel a slight hesitation then she takes off. I read on a site that you should putbin tank fuel press reg from 5.0 tank in ranger tank? don't know why, 3.0 fpr is set at 60 psi and the reg on 5.0 rail sets it to 35...or am I missing something. maybe I am not getting enough fuel as apposed to too much air?