Hey all i'm new to the forums but i've been really struggling with my ranger. I have a 97 4x4 4.0 v6. I have been passed inspection for a couple months because I'm struggling to get my check engine engine light off. My truck also idles super high. my truck idles around 1100 rpms and im stuck with codes p1445 and code p0153. Thanks

 

Welcome to the forum

P1445 will be the hard one to get rid of, EVAP system codes are a PITA
EVAP system uses engine vacuum to put a lower pressure in the SEALED gas tank, this prevents gasoline fumes from polluting the air while vehicle is moving and the gasoline is sloshing around in the tank
It has a couple of solenoid valves and a pressure sensor, plus LOTS of hoses, lol


Never Google Codes first, look them up on a full list like this one for Fords: https://www.therangerstation.com/tec...II_codes.shtml

There are several codes for each system, so the codes the computer does NOT choose are just as important as the code it does choose

P0153 02 Sensor Circuit Slow Response (Bank 2 Sensor 1)

O2 sensors are the ONLY sensors that wear out, they use a chemical reaction to detect Oxygen in the exhaust, and they run out of chemicals
100k miles or 12 years is their limit
4cyl engines just have Bank 1
V6 or V8 engines have bank 1(passenger side), and Bank 2(drivers side) Ford
O2 sensor "1" indicates O2 closest to the engine, upstream
O2 sensor "2" is an O2 after Cat Converters, downstream

So Bank 2 sensor 1 is the O2 sensor closest to the engine on Drivers side exhaust
Slow switching usually means O2 has run out of chemicals
If you don't have a history on when the O2s were last changed on the 25 year old vehicle, which should be on its 3rd set of O2s, I would change all 3 O2s
You MPG will for sure improve
If you have full Dual Exhaust you may have two sensor "2s", but most Rangers just had the one O2 sensor "2"

But at least change B2S1 O2 to see it that helps
Or you can swap B1 and B2 sensors and see if code changes to P0133 02 Sensor Circuit Slow Response (Bank 1 Sensor 1)
Indicating a failed O2 sensor


P1445 Purge Flow Sensor Circuit High Input
This is a "circuit" code, so wiring or sensor issue, usually not always

In the engine bay usually on drivers side at the front is the EVAP canister mounted on Rad support
It will have some caps on top and two hoses
One hose runs back to the gas tank
The other hose is the one you want, it runs to the engine and will have two devices on this hose

From canister the first device will be a 2 wire solenoid valve, you can test this with 9v battery or car battery, 12v(9v) and negative, there is no polarity, as long as one ternimal is + and the other - the solenoid should "click" open and then "click" closed when power is removed
No "click" means its broken

The next device, closer to engine on the hose is the Purge flow sensor, 3 wires
Not really an easy test for this sensor, but if the solenoid tested as OK then its most likely this sensor is bad

P1445 Purge Flow Sensor Circuit High Input high
Means the computer opened the solenoid and the Purge sensors pressure didn't drop as expected, so could be a bad solenoid or a bad sensor
Could also be a clogged canister/hose, as well, which is why EVAP codes are a PITA to diagnose

And just a heads up, even after you "fix" the EVAP system and Clear the Code, the computer needs to run a few tests on it over a few days, so code will stay until computer gives it a "pass"

Seen here on drive cycle tests: Ford Motor Company Driving Cycle

 

Hey RonD thank you for the feedback. I changed all 3 of the o2 sensors about 4 months ago because i was having the same issue and they were gone for a while but now back on, i also changed both the purge solenoid and the flow valve about 2 weeks ago still no luck. Think maybe its a wiring issue and advice on where to start? also any idea on why my engine is idling so high?

 

New parts can be a b!tch, can't trust them now-a-days, more on that later

After engine is warm up and idling high
Unplug the 2 wire connector on IAC Valve
RPMs should drop to 500, engine may even stall, either is good, no vacuum leaks

If that happens then Computer is causing the high idle, its holding idle high for some reason

If idle RPMs do not drop then IAC valve is stuck or you have a vacuum leak
Pull off IAC valve, just 2 bolts
Plug in its connector
Turn key on, engine off
Look at the valve inside the IAC valve
Unplug connector, should see the valve move a bit
Plug connector back in, again it should move
It only moves 3/8" but does move

It its not moving
Unplug it and try to move it with screwdriver or ??
Plug it back in and see if it moves now, unplug/plug in, repeat

Google: Ford Clean IAC Valve

Reinstall and see if engine idles lower after warm up, cold engine WILL idle high

If computer is holding IAC Valve open then that could explain P1445 and P0153, you have a failing computer


New parts
We all wanted less expensive parts, and we got them
Problem is, what makes parts expensive is the Quality Control, that's labor, testing parts before shipping them, Motorcraft(Ford) parts are way more expensive because Ford pays for Quality Control, they can't afford to put untested parts in new vehicles
But its often silly to pay the extra for these

Less expensive parts are not tested, but have a 1 or even 2 year warranty, which is much cheaper than Quality Control
So "heads up", new does not mean "it works", just means that no human has touched them, YOU are the first, lol

Swap the 2 upstream O2 around and see of the code stays the same or changes to other side

The "slow switching" code is the troublesome thing, lean codes or rich codes are a bit easier to diagnose
If O2 is new and you get same code it could be exhaust on that side is partially blocked

Is there a separate Cat converter on each down pipe on a 1997 4.0l?
If so tap on each with rubber mallet or piece of wood and listen for rattling sound inside the converter
Tap on other converters to see if they sound different


For the EVAP system read here: https://www.ranger-forums.com/4-0l-o...e-445-a-37919/

And here: https://www.ranger-forums.com/4-0l-o...-input-151804/
Last post is a good one, lol


If it is a computer issue, and there is NO test for that, then you need to get another PCM(computer)
Only way to determine if its the PCM is to do all the tests you can on why the codes are there, if the codes shouldn't be there then its a PCM issue

 

So if the engine is holding the IAC open could it give it a rough idle? my truck surges while idling and idles around 1400 in park but idles around 1100 in gear. Thank you for the advice

 

Computer holds IAC valve open, yes it can cause lean mix so rough idle, like a vacuum leak can

 

EVAP codes are a pain in the rear. You could be some of the cause of the problem and not knowing it.

Are you filling the tank as full as you can get it and I mean after the gas pump kicks off adding another dollar or two to the tank so to avoid a future fill up? When the gas pump kicks off it is okay add a few cents or so to round up to the nearest dollar but dont add two or three gallons.

Reason being is there is a line that basically runs to the charcoal system or some other emission system. By you filling the tank way past full, you are running raw, liquid fuel into the evap/emission system.

On the other end of the problem is running fuel tank as low as you can go without filling up. Your fuel pump is submersed in fuel not only for picking up fuel but it does keep the pump cool since it is electric. Factory pumps are actually quite good. Most time I bet that if someone is having a fuel pump issue it is because they run the tank on empty all of the time. Once I get to about an 1/8th tank and usually 1/4 I fill up.

Dont over fill a tank and dont run it totally empty.

 

I dont over fill or run to empty. but i did buy the truck from someone else who I don't think managed it well at all, when i got it it was very beat and there were a lot of mechanical hiccups that i had to fix just because of his work. for example the purge solenoid and flow valve were on two seperate lines the solenoid was the on the line that ran from the gas tank

 

Changed pcm not really a change in the idle. It was idling super rough but for some reason when I unplugged the ac pressure sensor it started to idle a lot better. Any ideas as to why that is?

 

Because you removed a "load" on the engine
Rough means misfires, if engine has no load you don't feel the misfires as much, add a load and misfires are more noticeable, felt/seen more

 

I know have 6 codes on my truck and can’t seem to figure out any solutions for them. Here are the codes P1445 P0171 P0174 P0113 P0122 P0153
If anyone knows anything to check for or maybe how you fixed them please let me know I need to get my truck inspected. Thanks

 

1997 Ranger 4.0l

P0113 Intake Air Temperature Circuit High Input
P0122 Throttle/Petal Position Sensor/Switch A Circuit Low Input

P0153 02 Sensor Circuit Slow Response (Bank 2 Sensor 1)
P0171 System too Lean (Bank 1)
P0174 System too Lean (Bank 2)

P1445 Purge Flow Sensor Circuit High Input

Whats the age of the O2 sensors?
Have YOU changed them, since you owned this Ranger?
If not change them

Test fuel pressure, 30-35psi is expected
Test Vacuum, hold RPMs steady at 2,500, vacuum should be steady, if slowly dropping then you have clogged exhaust

In the middle of upper intake on drivers side is the 2 wire Air Temp sensor, unplug it and check its connection for corrosion
Do the same for the TPS(throttle sensor), 3 wire upper intake at the front

Good read here for P1445: https://www.ranger-forums.com/4-0l-o...e-445-a-37919/

 

Hey RonD thanks for the reply, do you know where to find a vacuum diagram for my ranger? I can’t seem to find one anywhere