When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
The downstream sensors don’t have anything to do with the motor. They just tell you if the catalytic converter is working properly. And it’s difficult to figure out what worked when you change a lot of things but hey, if it runs good now you got it made
I spoke to soon drove it for 100 miles put injector cleaner in it also. Parked it went outside started it up to go to the market and codes back. I think injectors or computer is next.
P1131 Lack of Upstream Heated Oxygen Sensor Switch - Sensor Indicates Lean - Bank No. 1 P1151 Lack of Upstream Heated Oxygen Sensor Switch - Sensor Indicates Lean - Bank No. 2
Always good to post code numbers and definitions so we are on the same page
These are different than regular "lean codes" "Lack of switching" is whats different Regular lean code( P0171 System too Lean (Bank 1)) would mean O2 is working, changing voltage, but showing high oxygen that computer expected so its having to add more fuel than calculated
2000 Ranger fuel pressure should be 55 to 65psi, standard for 1998 to 2011 Rangers, 1997 and earlier was 35psi So what is your fuel pressure engine running?
O2 sensors generate their own voltage 0.1v is high oxygen, or lean 0.9v is low oxygen or rich
0.0v would be lean and can be caused by broken wire or broken sensor "Lack of switching" means voltage from O2 sensor is not changing even if computer adds more fuel
O2 sensors use a chemical reaction to detect oxygen in exhaust, and can't work until they are above 600degF Which is why engine can run better cold until computer starts to use O2 sensor in its air/fuel calculations
O2 sensors are the ONLY sensors that wear out, they run out of the chemicals, 100k miles or 12 years which ever comes first is when they should be changed for new ones
You can get a Bluetooth OBD2 reader for $15 to see Live Data from each O2 sensor Or if your current OBD2 reader has that function have a look at the voltage on each O2 sensor If its stuck at 0.0v then its a wiring issue usually, but in any case get new O2 sensors if they are over 12 years old, they come with new wires attached
I will have to look at towards the weekend. We are expecting 4 days of rain and I have to work on it outside. The p174 code is still going strong and I now have a p0443 and that’s for the purge valve. I already switched the purge valve with a whole new assembly because that is the item that rotted off with the hoses and started me down the rabbit hole. I pulled the new valve and tested it. The valve holds pressure and switches fine with power to the tabs the ohms are in the normal range 63 ohms. It also has the correct voltage going to the input wire from the truck. The computer will throw the code right after it is cleared to the point clearing the code does nothing.
I was thinking about doing injectors anyway because the trucks age and the condition of the spark plugs, Just leaning to a new computer also, It seems a lot of parts being thrown at the truck but being the age of the truck most parts had to be changed. O2 sensors, spark plugs, wires, new fuel and air filter. The purge valve and the egr solenoid both had failed under test and had to be changed. The other parts I changed because of trying to chase the problem. The fuel pump and fuel regulator had been switched because of the fuel pressure.
I did not have a problem with the purge valve till I put in a bottle of Techron and I know that the Techron is not the problem I was just hoping it would clean out the injectors. I’m afraid to take the intake apart because everything I seem to touch is braking because of the rust and rot.
I really appreciate all the help just wish I could come back and say it’s all fixed. I never had this much problem chasing codes before.
for about $25 or less you can get an ELM 327 OBD2 bluetooth or wifi sender.. then free or less than $10 there are apps for phone or tablet. you get codes and all the information. codes just till you there is a problem. you need to figure out why there is a code. look at all the information you can, not just the code you are getting.
Just got the topdon topscan pro and scanned the truck got to say it does a lot for a 100 dollars. looks like I’ll be checking wires. The sensor for bank 2 looks funny. P174 was for bank 2 and the 02 sensor reads rich shows no voltage.
Cats probably will have to be replaced at some point but the no voltage on the o2 b2 is the one that keeps throwing the code p174. I guess I have to check the wiring that’s a brand new sensor and I checked the ohms before and it checked out. If the cats are blocked I wonder if that could be the problem but wood not effect the no volts on the o2 sensor.
Cats probably will have to be replaced at some point but the no voltage on the o2 b2 is the one that keeps throwing the code p174. I guess I have to check the wiring that’s a brand new sensor and I checked the ohms before and it checked out. If the cats are blocked I wonder if that could be the problem but wood not effect the no volts on the o2 sensor. I will look for wiring issues but I might also Lean towards a pcm if I can’t find it.
when was the last time the O2 sensors were changed? that could be the problem. if you have to pass an air quality test then later worry about the cats.
All 3 have been changed in the last 4 days and this is the full report If you scroll down you’ll see that the 3rd cat is getting voltage but it will not let me graph that 02 sensor but I can graph both on bank 1 the up and downstream just not bank 2 it will not let me do anything to that one.
yes i see bank 1 sensor 1 voltage and bank 2 sensor voltage. O2 sensors generate their own voltage 0.1v is high oxygen, or lean 0.9v is low oxygen or rich
bank 1 sensor 2 will not effect the the motor, for now dont deal with it now....
what i would do is switch 1 and 2 then take a reading. if its the same, id think its a wiring or ECU issue. if it reads the opposite its a bad sensor.
I keep reading that "injectors are next", but have you actually tested/checked the injectors yet? Not just put injector cleaner in it and not just pulled them to see if they work but flow tested?
If the truck sat for a "couple years" and is running rough and lean, it's definitely a possibility, esp with the crappy fuel we have now.
Easy check before even diving into replacing the injectors:
If you have an infrared thermometer, check temps of each exhaust manifold pipe individually right at the port. This isn't an exact measurement but will give you a quick & easy & rough idea of what's happening in each cylinder.
Assuming you really have no vacuum leaks left, the rail is holding pressure, the regulator is keeping the pressure consistent and the pcm and coils are functioning properly, the truck should run smoothly if the injectors are giving each chamber the same amount of fuel and exhaust temps similar. These injectors only have (4) holes, and can easily be partially blocked, sticky, and/or functioning intermittently. Yes plug reading can show this as well, but NOT ALWAYS, esp if the plugs are still working intermittently or not flowing as much as they should.
Good luck!
Thanks for the info and with further inspection it looks like it’s number 5 that’s a problem. The computer was giving a misfire on that cylinder only when you gave it gas and I did not see that before. When it was not doing it at idle. I checked the coil pack, wires and spark plug on that cylinder and all should work as they should. The misfire looks like it is a stuck or sticking injector. It’s kind of funny because I looked for misfires and did not see anything nor did I get a code. Just happened to check something again and the misfire will happen at idle now and when I give it gas. Just not all the time
questions is do I switch all because I got it apart or just the one.
I suppose you could verify that by changing number five injector and number four injector just swap them and see what happens. in my case I have more time than money. I’m not sure what injectors cost or if you can get rebuilt certified ones.
You can get Bosch 3rd gen 4 hole squirters for about $300: actually gonna do my 97 with 220K miles: or on a rebuilt, as mine is starting to smoke quite a bit: likely valve guides, as it sat for about 8 years before I got it and rebuilt the entire under carriage.
Judgejohnmd
It seems you've got it mostly sorted, but here's another way to test the injectors from the legendary RonD:
Try the "Clear Flooded Engine" test
Turn on the key Press gas pedal down to the floor, and hold it down. This turns OFF fuel injectors Try to start engine, it should just crank and not fire If it starts then you MAY have a leaking injector(read at the bottom)
I do this every morning when starting my high mile 4.0l(400k) to get oil pump thru the engine before I release the gas pedal and it starts
When computer sees WOT(wide open throttle) at 0 RPMs it will not pulse(ground) the injectors, so driver can "Clear a Flooded Engine"(dry it out), all fuel injection computers have this, not a Ford thing If engine started, then you MAY NOT have WOT Press gas pedal down to the floor with a stick against the seat Go to the engine and see if you can manually open the throttle a little more, if so Google: Ranger throttle cable mod
If you have WOT then disable spark, pull the coil wire to distributor Cycle key on and off a few times Do Clear Flooded Engine again, and crank it a few times with foot to the floor Now start pulling out spark plugs, the one with the WET TIP is the one with leaking injector
This helped me when I had lean codes to determine that it wasn't my injectors, but something else. Your case is different, but it couldn't hurt to try this out.
Ron, if you're reading this, forgive me for plagiarizing!
Just figured I would get back. Got the injectors delivered the other day and installed them. Truck runs great and no new codes. When I pulled the injectors 5 was needing of love and 3 was not far from it. So it looks like a new set of injectors was needed.
Thanks for all the help and suggestions.
