1996 Ford Ranger 4x2 (Splash)

[DavidW]

Engine idles very rough and have to keep foot on accelerator to keep running. I know I have 1 bad spark plug wire and have replace the plugs. I do have 2 OBDII error codes, one has to do with the engine temp gauge (I put in a analog one) and an emission error (purge valve solenoid). Any assistance would be sincerey appreciated and will follow-up with any recommendation.
Thanks;
David

 

[RonD]

Welcome to TRS

Need exact code numbers

There is no code for temp gauge or its SENDER, there are several codes for ECT(engine coolant temp) Sensor, nothing to do with temp gauge its a sensor, only used by the computer

EVAP code wouldn't cause engine problems

ECT sensor issue can cause rough running
IAC(idle air control) Valve can, of course, cause idle issues, it can be cleaned, read here: https://www.explorerforum.com/forums/index.php?threads/iac-valve-cleaning-thread-w-pics.84220/

Also on the 4.0l OHV Rangers(1990-2000) you need to clean the MAF sensor every year or so, easy to do
This is not your problem as described, just a heads up
Dirty MAF sensor causes bogging and stumbling when driving, but idle would be OK

 

[DavidW]

Welcome to TRS

Need exact code numbers

There is no code for temp gauge or its SENDER, there are several codes for ECT(engine coolant temp) Sensor, nothing to do with temp gauge its a sensor, only used by the computer

EVAP code wouldn't cause engine problems

ECT sensor issue can cause rough running
IAC(idle air control) Valve can, of course, cause idle issues, it can be cleaned, read here: https://www.explorerforum.com/forums/index.php?threads/iac-valve-cleaning-thread-w-pics.84220/

Also on the 4.0l OHV Rangers(1990-2000) you need to clean the MAF sensor every year or so, easy to do
This is not your problem as described, just a heads up
Dirty MAF sensor causes bogging and stumbling when driving, but idle would be OK

P0117, P1443, & P0174
Here's some screen shots of my RPM's.
That's as many as I can upload at this time

I hope this helps.

 

[RonD]

You don't need to upload RPM pics, just saying idle RPMs are not stable is enough

It is good to look up codes on a full list, like here: https://therangerstation.com/tech_library/OBD-II_codes.shtml

Each sensor or control will have multiple codes the computer can use to notify owner of a problem, so the codes it doesn't use, can be as helpful as the ONE it did use

P0117 Engine Coolant Temperature Circuit Low Input
This is the ECT sensor and it means the computer is not seeing voltage changing as it should as engine warns up
ECT sensor is not an expensive part, and while you can test it with a volt/ohm meter most chose to replace it
This will be on the lower intake above thermostat housing
It will have TWO wires connected, one will be Grey/red stripe
Replace ECT sensor

This can help the idle to stablize, but still plan on cleaning the IAC Valve


P0174 System too Lean (Bank 2)
Bank 1 is the passenger side of an engine, or the only bank on a 4 cylinder engine
Bank 2 is the drivers side of an engine
This code means the computer is having to open the fuel injectors longer than it calculated on Bank 2
This can be because O2 sensor on bank 2 is getting too old
O2 sensors last 150k miles or so and then wear out

Lean code can be a vacuum leak or dirty MAF sensor but.......................you would get Lean code on Bank 1 as well
An exhaust manifold leak on Bank 2 can cause this code, but you should hear a leak like that
Could be a dirty fuel injector on Bank 2, run a can of Seafoam or similar cleaner in the gas tank, also helps with smoother idle

So if you don't know how old the O2 sensor is I would replace it, and the one on Passenger side as well
The O2 sensor in the back, behind Cat Converter lasts longer, leave it



P1443 Evaporative Emission System Control Valve (low/no flow)
Won't cause any problem with engine operation
It means that when the computer opens the Vacuum valve to suck air from the gas tank nothing is happening
This can be because the vacuum valve/solenoid is not working
The sensor that detects flow is not working
Or vacuum hose is broken
It can also mean the computer itself is broken, but hopefully not

You will need a volt/ohm meter and a vacuum hand pump would be handy, to find out the problem
Or you can just swap out the 2 parts, solenoid and sensor
Obviously check the hoses first

 

[DavidW]

You don't need to upload RPM pics, just saying idle RPMs are not stable is enough

It is good to look up codes on a full list, like here: https://therangerstation.com/tech_library/OBD-II_codes.shtml

Each sensor or control will have multiple codes the computer can use to notify owner of a problem, so the codes it doesn't use, can be as helpful as the ONE it did use

P0117 Engine Coolant Temperature Circuit Low Input
This is the ECT sensor and it means the computer is not seeing voltage changing as it should as engine warns up
ECT sensor is not an expensive part, and while you can test it with a volt/ohm meter most chose to replace it
This will be on the lower intake above thermostat housing
It will have TWO wires connected, one will be Grey/red stripe
Replace ECT sensor

This can help the idle to stablize, but still plan on cleaning the IAC Valve


P0174 System too Lean (Bank 2)
Bank 1 is the passenger side of an engine, or the only bank on a 4 cylinder engine
Bank 2 is the drivers side of an engine
This code means the computer is having to open the fuel injectors longer than it calculated on Bank 2
This can be because O2 sensor on bank 2 is getting too old
O2 sensors last 150k miles or so and then wear out

Lean code can be a vacuum leak or dirty MAF sensor but.......................you would get Lean code on Bank 1 as well
An exhaust manifold leak on Bank 2 can cause this code, but you should hear a leak like that
Could be a dirty fuel injector on Bank 2, run a can of Seafoam or similar cleaner in the gas tank, also helps with smoother idle

So if you don't know how old the O2 sensor is I would replace it, and the one on Passenger side as well
The O2 sensor in the back, behind Cat Converter lasts longer, leave it



P1443 Evaporative Emission System Control Valve (low/no flow)
Won't cause any problem with engine operation
It means that when the computer opens the Vacuum valve to suck air from the gas tank nothing is happening
This can be because the vacuum valve/solenoid is not working
The sensor that detects flow is not working
Or vacuum hose is broken
It can also mean the computer itself is broken, but hopefully not

You will need a volt/ohm meter and a vacuum hand pump would be handy, to find out the problem
Or you can just swap out the 2 parts, solenoid and sensor
Obviously check the hoses first

Thank you for your assistance. Looks like a trip to the partshouse tomorrow with a wad of cash and get these parts. Will follow-up tomorrow with my progress.

 

[RonD]

You only need the ECT sensor, IMO, $10

And to clean the IAC Valve

The O2 sensor(s) can wait, but if they are on their last legs the MPG goes down a bit, so new ones will pay for themselves over the next 150k miles

 

[DavidW]

You only need the ECT sensor, IMO, $10

And to clean the IAC Valve

The O2 sensor(s) can wait, but if they are on their last legs the MPG goes down a bit, so new ones will pay for themselves over the next 150k miles

I cleaned the IAC Valve and the Mass Air Flow Sensor, that seems to help the idle issue. It idles at about 900 RPM's now. Thank you. I will replace the ECT Sensor tomorrow and the spark plug wires, since #6 gives a shock when touched (the others do not).
Thank you again for your help.

 

[RonD]

For spark plugs and spark plug wires check with Local Ford Dealers, I know that sounds odd, lol

But my 2 local Ford dealers run "tune up" specials a few times a year, and I can get OEM wires and/or spark plugs for same price or less than discount brand at Parts store.
Free phone call to ask

 

[DavidW]

For spark plugs and spark plug wires check with Local Ford Dealers, I know that sounds odd, lol

But my 2 local Ford dealers run "tune up" specials a few times a year, and I can get OEM wires and/or spark plugs for same price or less than discount brand at Parts store.
Free phone call to ask

Thanks for the tip, I will check with them.
I just test drove the Ranger. The RPM's still drop but not like before. I think when I came to full stop, the RPM's went down to 4 or 500. I think tomorrow I'll get the new wires, ECT Sensor, IAC Valve and MAF Sensor. Will follow-up. Thanks again.

 

[RonD]

The idle is set by the computer, it controls the IAC Valve, and it is accurate +/- 3RPM

So..........reads like computer or IAC Valve is not responding
After engine is warmed up and idling unplug the 2 wire connector on IAC Valve
RPMs should drop to 400-500 or engine may even stall, either is good it means IAC Valve was open a bit and is not stuck
If RPMs don't change then IAC valve is not working

This is also a good way to test if there is a Vacuum Leak, with warmed up engine, automatic trans idle should be 750-800rpms in Park
Unplug IAC valve and RPMs should drop, as above, to 400-500rpms, if not there is a vacuum leak somewhere.
When you shift into a gear the computer should bump up RPMs by 50, also if AC is on samething, computer should bump up RPMs
This is all done with IAC valve

You can see IAC valve moving if you take it off the intake, and plug its wires in
Turn key on
IAC Valve should open all the way with Key on for starting
Look at the valve and unplug the 2 wires, valve should close
Plug wires back in and valve should open
It only moves 3/8", less than 1/2" but does move

 

[DavidW]

The idle is set by the computer, it controls the IAC Valve, and it is accurate +/- 3RPM

So..........reads like computer or IAC Valve is not responding
After engine is warmed up and idling unplug the 2 wire connector on IAC Valve
RPMs should drop to 400-500 or engine may even stall, either is good it means IAC Valve was open a bit and is not stuck
If RPMs don't change then IAC valve is not working

This is also a good way to test if there is a Vacuum Leak, with warmed up engine, automatic trans idle should be 750-800rpms in Park
Unplug IAC valve and RPMs should drop, as above, to 400-500rpms, if not there is a vacuum leak somewhere.
When you shift into a gear the computer should bump up RPMs by 50, also if AC is on samething, computer should bump up RPMs
This is all done with IAC valve

You can see IAC valve moving if you take it off the intake, and plug its wires in
Turn key on
IAC Valve should open all the way with Key on for starting
Look at the valve and unplug the 2 wires, valve should close
Plug wires back in and valve should open
It only moves 3/8", less than 1/2" but does move

So are ya saying, it maybe the PCM/ECM which is located on the passenger side, back firewall?
I will try the IAC tomorrow morning. Thanks for the information.

 

[DavidW]

So are ya saying, it maybe the PCM/ECM which is located on the passenger side, back firewall?
I will try the IAC tomorrow morning. Thanks for the information.

I went out and started the Ranger, when I unplugged the IAC Valve, the engine died.
When I took off the IAC valve and just turned the key to 'ON', the IAC valve did not move and just made a puff noise.
I guess the IAC is bad. Your advice and recommendation please.

 

[RonD]

While it was off the intake with key on, did you unplug and plug in the IAC valve wires a few times to see if was just intermittent or not moving at all

The IAC valve is just a 12volt solenoid, with key on engine off, computer gives it 12volts so it opens all the way, when you unplug its wires the spring inside will push valve closed, when it has 12v again it will open, repeat as you see fit to make sure it works every time

If not replace it

 

[DavidW]

While it was off the intake with key on, did you unplug and plug in the IAC valve wires a few times to see if was just intermittent or not moving at all

The IAC valve is just a 12volt solenoid, with key on engine off, computer gives it 12volts so it opens all the way, when you unplug its wires the spring inside will push valve closed, when it has 12v again it will open, repeat as you see fit to make sure it works every time

If not replace it

D

While it was off the intake with key on, did you unplug and plug in the IAC valve wires a few times to see if was just intermittent or not moving at all

The IAC valve is just a 12volt solenoid, with key on engine off, computer gives it 12volts so it opens all the way, when you unplug its wires the spring inside will push valve closed, when it has 12v again it will open, repeat as you see fit to make sure it works every time

If not replace it

I did it a couple of times, the spring never moved, the IAC just made a little "pop-type noise" like it was trying to do something. It appeared to be stuck trying to move.

 

[RonD]

Reads like its broken, replace it