Hello Ranger Forums! This post has been a long time coming. I came into possession of a 1992 2.3 Ranger Sport and have been tinkering with it for awhile. I’ve got TONS of information and I’m determined to fix.

I have the service manual, electrical and vacuum manual, and power train and emission manual. I even got my hands on a break out box! First ford I’ve worked on so I’m generally lost and confused.

LOTS of info here but I’m sure helping me will earn you some serious karma points :)


**TLDR: code 173 that I can make into a 172 but won’t go away and can’t pass smog here in California and no I can’t move out pls help**


Here’s the current situation as of today:

- Currently truck’s ONLY code is a 173 code when running koeo and koer tests.
- I can fool the computer to thinking there is a 172 code by grounding out the Hego sig Return from O2
- Exhaust does seem to lean out when grounded
- Truck runs and starts very well
- Rpm’s sit at about 500 on tach
- Minor surge during warm up until warm. Stops with pedal input during that period
- Vacuum strong and no leaks detected
- Fuel pressure holds steady at lower end of values specified in book


i have a ton of information for the truck so here we go (deep breath)

Here are some background details from when I first got the truck:
- fixed a clogged up EGR all the way down the pipe
- fixed wrong egr position sensor with Motorcraft part
- Removed a weird extra connector piece on egr control solenoid (can’t find any information on what this piece is)
- Replaced a burned out Cat
- Replaced wrong 3 wire HEGO with NTK 22500
- Hego wires coming from vehicle harness all mixed up (could use help verifying order more details to follow)
- #1 spark plugs bridged. Spark plugs all new now
- Wrong timing belt. Installed new timing belt with right shaped ridges
- Broken vacuum lines going to egr position solenoid
- Wrong plug wire orientation
- Removed buzzer.. my god.. that noise..

in addition, I was able to get a bunch of new parts since the hope was to taking the truck on a cross country trip. Here’s what else is new:
- New Motorcraft plug wires
- Both ignition coils new
- New throttle position sensor
- Fuel filter
- Recently changed oil and filter. Looked fine
- Reapplied thermal paste and cleaned surfaces for ground to DIS
- New water pump and thermostat
- New MAF sensor
- New fuel pressure regulator
- All new valves seated and new valve seals installed
- Fresh battery
- New exhaust manifold, install manifold, upper intake manifold gaskets
- New air filter
- New Motorcraft PCV
- New oil cap
- New coolant
- New radiator cap
- New zip ties on gap pedal cable
- ECM capacitors replaced. Two total found. Both leaking no changes after replacement


So how can you help me? Here’s a few questions I need help on:

+ Can you help me verify the was the wires are supposed to be set up coming out of the vehicle harness to the HEGO? The books call each wire about 3 different things. My current orientation is (looking into connector):
1: top left (blk/wht wire) - pwr gnd going to white Hego wire
2. top right (o/blk wire) - ignition run circuit going to other white HEGO wire
3: bottom left (Gy/Lb wire) - Hego circuit pin 29 going to blk HEGO wire
4: Bottom right (O wire) - Hego gnd pin 46 going to gry HEGO wire

+ Can you tell me where you order your parts? I’ve worked on a few Hondas and love Honda majestic but many ford parts dealers ships don’t show me parts numbers for discontinued parts and the manuals only give me partial part numbers.

+ Can you tell me the correct injector numbers? My current ones don’t seem stock and could be an issue

+ What was the extra piece attached to my egr control solenoid? Small black piece about 4 inches long and just wide enough to connect to sensor and harness running to egr

+ Anything else you can think to question I will test promptly

I sure would like a carburetor right about now. Smog test information for a few smog checks available and willing to share.

 

Welcome to the forum

Will be hard to diagnose with so many new parts
"New" no longer means tested and working, it means NEVER EVER TESTED, but we will replace it free if, YOU TEST IT, and if it doesn't work and you bring it back, lol

You should just have the one O2 sensor, 4 wires
2 wires are for its internal heater, a 12v key on wire(orange/black or grey/yellow) and a ground wire(black or black/white)

2 wires are for the sensor part of the O2, O2s generate their own voltage once they are heated above 650degF, just FYI
orange to computer pin 49(this is a shared wire, most sensors are connected to this same pin 49) and grey/blue to pin 29

O2 sensor voltage is 0.1v lean, 0.9v rich, so disconnecting a wire would change it to 0v, so lean, false lean but lean code set

Here is a look at popular O2 sensor wire colors: https://i.pinimg.com/originals/0a/42...f87d9d5523.jpg

Heater wires have no "polarity" as long as one wire is 12v and the other a ground heater will work, which is why they are both the same color on the O2 sensor wire harness
Both black, both brown, both white, there is no order/polarity

The orange wire for the sensor is the "ground", not really a ground but a reference ground
Grey/blue wire, pin 29 is the "signal" wire



All gasoline engines need to be Choked on cold start
Fuel injection uses the computer to "choke" the engine, Rich fuel mix and high idle, which is what the Choke did on a carburetor
Engine has a ECT(engine coolant temp) sensor that tells the computer when coolant gets to 140+ degF so no longer needs choke
5 volt ECT senor is only used by computer
There is a 12volt temp SENDER on the engine as well, for the dash temp gauge

So RPMs should be higher on cold start, 1,000rpms to 1,200rpms depending on outside temp
Then slowly drop as engine warns up
Warm idle on a 4cyl engine should be 700-750rpms with manual trans 800rpms with automatic
4cyl engines vibrate too much under 700rpms because they only fire every 180deg so they always idle higher than V engines, just FYI


Once O2 wiring is set reset computer to clear it, don't just clear the codes


If rich code returns check the Vacuum hose on the FPR(fuel pressure regulator) if its leaking a bit(its NEW so never ever tested) raw fuel will get sucked in to the engine via that vacuum hose
Replace it if gasoline is seen there


Yes, injector size
People often confuse injectors with Jets in a carb
Bigger injectors means MORE POWER.............not the case of course just means Rich codes, as you suspect

The 2.3l used 14lbs/hour injectors, but unless you know what you have in there now it will be hard to tell if they are the wrong ones, you would need a part number and then the maker of that part would have to publish the pounds per hour rating which can be very hard to find from most makers
If previous owner put in 19lbs/hr injectors then you would get Rich codes

If you have a fuel pressure tester then you can test if pressure holds after key off, it should hold above 20psi for MONTHS and MONTHS, 15psi would be OK
Running pressure is 30-40psi
If pressure drops to 0psi shortly after key off then could be a leaky injector
After shutting off warm engine, pull off the air tube from upper intake, open throttle and smell inside intake, should be NO GAS SMELL at all, if you smell gas you got fuel leaking in, check FPR vacuum hose if you haven't already

 

Hello Ron! I’ve seen many of your posts throughout the time it’s taken to work on the truck. Thank you for all your help then and now.

I’m not around the truck at the moment and will hopefully get a chance to test out that ECT sensor and reply to a few things later today.

Also thanks for the catch. I meant pin 49 instead of 46 for that HEGO harness wire. Pin 49 splits to 46 and I was looking at my note. I’ll be double checking the harness against your information later too.

but while I’m out and about I had a few thoughts:

You pointed out that fuel pressure should stay at 20 for months but mine definitely drops below that within a day and that got me thinking about the injectors so I went out to check them last night. The ones currently installed are Ultra-Power MFI690 and I’m unable to find much on them but I did find a link from rock auto. A quick Google search tells me they aren’t great.. I just ran to my storage unit because I thought I had others. These have a Ford logo Denso injectors numbered F03E-A2B. Bringing them home with me just in case. Besides that fuel pressure sits right at 30 while running. I think minimum while key on engine off is 35 which it sits at well too. I think the book says it should maintain that for a minute or so which it does.

Another thing you mentioned that caused me to scratch my head is the voltage range for the HEGO. I’m able to watch the voltage rise from 0 to 1.1 in maybe 45-60 seconds by just turning the key and letting the sensor warm up. I had thought I’d seen a larger range but I could have just been mistaken with the 5v that is used throughout the ECM. What’s going on here? Seems the sensor is telling the computer to go rich before the engine is even on?

 

Taking some readings and looking some of the stuff over.

ECT sensor was showing open line at temperature but was giving me 1.1v measuring from pin 7 to 46. Since it shares a return wire through pin 46 with the HEGO pins 46 and 49 mentioned above and I know almost nothing about electronics this makes sense to me? Since I’m also assuming this 1.1v is the voltage generated by the Hego?

According to a chart in the manual it looks like this would mean I’d see a lower voltage as heat increases.

The HEGO pretty much pegs itself to 1.1v. Since I’m getting an open between those 7 and 46 pins that would make me believe the computer is just not getting a heat value and assuming it’s super cold? Also getting open line at the connector.. but I’m pretty sure I’ve measured this before and got a low ohm value.

im thinking that the Hego would try to heat itself to 1.1 anyways and with a temperature input the engine would adjust the fuel air ratio appropriately bringing down that 1.1 to probably closer to .5? Am I on the right track here with how that would work?

will do some digging and keep you posted! Thanks again!!

 

O2(HEGO) needs to be heated to at least 650degF to work, so no readings will make sense until then

There is no temp voltage on O2

The ECT does have a 0.5 to 3.5volt temp scale, seen here: https://www.explorerforum.com/forums...art.24365/full

Under 1volt is fully warmed up(180degF), 3volts is about 70degF
Air Temp sensor uses the same scale, just FYI

46 is the refernce ground for the 5volt system used by the sensors, except O2, it only uses the ground reference not the 5volts, as said O2 generates its own voltage by a chemical reaction with Oxygen in the exhaust, high oxygen is 0.1v(lean), low oxygen is 0.9v(rich)
But the O2s chemical coating needs to be 650degF or higher to react with the oxygen
Even with the heater it will take cold engine 3 to 5 minutes running time to get an O2 hot enough to generate voltage

If you want to test the O2 sensor heat up the exhaust, let engine idle and unplug the O2 sensor, hook up volt meter to the 2 sensor wires(not heater wires)
Should see between 0.1v and 0.9v, but jumpy voltage not steady
REV engine and its should be jumping around like crazy

Idle should be RICH, computer ignores O2 at idle, and at WOT(wide open throttle)
Richer idle is needed so engine doesn't over heat, on ALL gasoline engines

 

I just went ahead and did that test to the o2. If I heat up the exhaust I get a steady 1.1v at that connector testing the non heater wires. If I rev the engine it’ll move around a lot but then jump back up to a steady 1.1

ECT seems to be functioning as far as I can tell now. Open line was with key off. Key on I get readings between those two pins that do change from cold to warm to cold again. Had checked wires and connector on driver side. I even get a code if that connector is disconnected.

 

1.1v would set Rich code, above idle RPMs

Did the voltage drop below 1v when you REV'ed the engine

The 2.9l used a MAP sensor, on the firewall, has a vacuum hose and 3 wire connector

Check the vacuum hose

Unplug the 3 wire connector and start the engine, it should set a MAP code, sanity test for computer

 

Yes, voltage did drop on quick revs. Pushing and holding accelerator down slowly would keep reading at 1.1. Pushing quickly and holding would drop the revs and they’d slowly climb back up but generally to closer to .9 not all the way to 1.1.

i have the 2.3 with a MAF. When I unplug the MAF I can hear a definitive drop in RPM that then steadies out though.

 

Little bit of an update. Took it for a drive to see what the o2 is doing at speed. Starting around 50-55 mph the o2 will be right around .4-.6 maintaining speed. As I coast it’ll drop all the way down to 1.0 and then once I idle it’ll sit 1.0-1.1
maintaining speeds below about 50 the o2 will continue to read near or at 1.0.

I took a short break and idled on the side of the road for awhile. Now the same speeds are all giving me .9 or 1.0 voltage readings holding steady. The only way to drop below .9 is a sudden release from f the gas pedal which will drop it to about .6 for a few seconds then rise back to .9 or 1.0

ECT pins have been reading and holding at .8

immediately after posting this the next straight away I was seeing a consistent range between .4-.8.

 

0.4 to 0.6v is what you want for best MPG

Idle doesn't matter O2 is being ignored and that won't set Rich code

The return trip will set rich code, BUT.................the odd thing is that the computer is not adjusting the air/fuel mix to correct the 1v(rich) when driving
But I assume O2 was not hooked up to computer during the test?

O2 sensor is Feedback
Computer opens injectors longer or closes injectors sooner to keep the O2 voltage at 0.4 to 0.6v
Computer calculates air/fuel mix on the fly based on RPM, MAP(intake vacuum) and throttle position
It then looks at O2 voltage
if its 0.1 to 0.3v(lean) it opens injectors a few milliseconds longer
If its 0.7 to 0.9v(rich) it closes injectors a few milliseconds sooner than calculated
Pretty simple set up for a computer, just crunching numbers, which is what "compute"rs are good at

Computer has 30% leeway either way for injector open time, it will set lean or rich codes if there is a 20+% deviation either way

Lean codes tend to be vacuum leaks, or MAF sensor
Rich codes tend to be fuel pressure too high, or leaking injectors or FPR, OR..........wrong injectors, too large

 

o2 was hooked up. I was getting readings from the two o2 wires via breakout box as I drove.

Just stopped for awhile and took a whiff with the throttle plate open and there’s maybeee a very faint smell of what older fuel would smell like.

At this point it seems the o2 is working order now, ECT is working, computer is trying to do its thing, no smells of gas in the air intake.. so Id say it’s worth ripping out whatever injectors are in there.

I’ve got these F03E-a2b injectors here.. do you happen to know if those are correct?

idle also seems like it is perfectly happy sitting at 500 now. I’m almost positive sometime last week it was sitting closer to 1000. Not sure what I did to do that!

Went into a store and checked smell of intake again. Smells less like fuel than before.

thank you for sharing all this information! Definitely helping here.

 

Found this awesome chart:

https://m.motormanfuelinjection.com/Motorcraft.html

matching up the number I gave you gives back a Motorcraft part number that is for my Ranger. I have them here and all 4 work when powered by a 9v so I’m just going to slap them in and see what happens. Will post back tomorrow. Thanks!

 

So O2 was hooked up to computer, then O2 was at max voltage, 1v, and nothing computer could do to lower that within its 30% window
I would say injectors are the wrong size, too much flow, at this point