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4.0L OHV & SOHC V6 Tech General discussion of 4.0L OHV and SOHC V6 Ford Ranger engines.

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  #26  
Old 09-24-2016
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OBD1 codes can be Manufacturer specific
Ford 3-digit code list here: OBD-I Diagnostic Trouble Code (DTC) Applications - Ford 3-Digit Codes

If reader can't connect then try the method shown in the video, using CEL to flash the codes

Vehicle Computers rarely fail, they are way overbuilt for their purpose, so they are way down on the list of things to check.
There is no way to test them, best thing, if all other tests have not shown the problem, is to pull out computer and open it up to check circuit board for water intrusion or damage
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  #27  
Old 09-24-2016
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Ok, I just did the KOEO diagnostic test and found these codes:
565 Canister purge solenoid circuit fault
556 Fuel pump relay primary circuit fault (this one may have happened when I pulled the relay while it was running in hopes of releasing the pressure in the fuel lines)
629 Converter clutch solenoid circuit fault
566 3-4 shift solenoid circuit failure

My book says to repair KOEO faults before performing tests with the engine running. Do any of these sound like they could be a possibility?
Thanks
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  #28  
Old 09-24-2016
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The plot thickens. I found a small amount of oil floating on the surface in the coolant reservoir. It has copper specks in it. The oil itself looks fine (not milky). Does anyone know what might cause this?

Also, the coolant level in the radiator keeps dropping, but the amount in the reservoir stays the same. Every time I start the engine, the coolant level drops. I've checked the exhaust, and there is no white smoke, and it doesn't smell sweet.

I know these engines have a tendency towards cracked heads but I would like to rule everything else out before having to tear into this engine. I don't have much time during the week to be replacing heads or head gaskets.

As for the original issue, I haven't run the engine running diagnostic tests yet, so I'm at a standstill. At the rate the coolant is leaving the radiator, I don't want to drive it very far.

Last edited by Ol' Red; 09-24-2016 at 07:14 PM. Reason: New information
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  #29  
Old 09-24-2016
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No cracked head or blown head gasket, reservoir would be bubbling, and level would for sure change.
The 4.0l heads don't just crack, if coolant level gets low and they are overheated the heads will crack faster than other heads, a weak spot in the casting between valve seats, over heating expands metal and they crack at that spot.

You could do a Glove Test, it would confirm or dispel cylinder leak.
OR, just top up rad to the very top and start engine, leaving rad cap off, watch what coolant does, give it a minute or so.
If coolant starts to overflow out of rad then you DO have a cylinder leak, if it doesn't then you don't.
Each cylinder has 150psi compression and 1,000psi when firing, if there is a cylinder leak into cooling system then that pressure WILL force out coolant from the top of the rad as air pressure flows into cooling system from the cracked head or blown gasket.

But you do have a cooling system leak, probably higher up so check upper rad, upper rad hose or heater hoses.

How the overflow cooling system works is pretty simple.
When you heat any liquid it expands in volume, that's how a Pressure Cooker works.
As engine heats the coolant it expands this builds up pressure in the system.
A Rad Cap has two valves, the larger one holds in this pressure until about 14psi(look at rating on cap), at 15psi the larger valve is pushed open and hot coolant flows out to BOTTOM of the overflow tank(reservoir).
The BOTTOM part is significant.
If there was any air in the cooling system it would end up at the high point of the system, the top of the rad.
So at 15psi the rad cap opens and any air in the system would be released and flow thru the hose to the BOTTOM of the overflow tank, and bubble up to the top.

After engine is shut off the coolant cools down and shrinks back to normal volume, so pressure in the system drops.
Any coolant or AIR that flowed out will cause pressure in the system to go to -1psi because volume is shrinking, that's when the smaller valve in the rad cap is sucked open and pulls COOLANT only in from the BOTTOM of the overflow tank back into radiator.

Very simple setup, and self purging of air.

If there is a leak in the system then as coolant expands it will release that pressure as it builds up, it will never reach 15psi, so no flow to overflow tank.
And after engine is shut off, air will be sucked in thru that leak hole so any coolant lost thru that leak will be replaced by AIR.
Dropping coolant level in rad but not in reservoir

High up leak because you are not seeing an obvious coolant leak on the ground, lower leaks tend to drip alot more since they are always leaking coolant, engine off or on.
Higher leaks have air leaking out on warm up and only leak coolant when engine is fully warmed up, hot coolant, hot rad and hot engine parts means any leaked coolant would evaporate fairly quickly, hard to find this type of leak.
But keep topping up the rad, you do not want a 4.0l to overheat.
You can rent a pressure tester so you can find a leak while engine is cold and full of coolant.
Or you can add a UV dye to coolant and then use a UV light to find where dye is leaking out.

Oily with copper flecks could be water pump bearing starting to go, check weep hole on the bottom of water pump for coolant leaking.


None of those codes should cause engine issue.
629 Converter clutch solenoid circuit fault
566 3-4 shift solenoid circuit failure

There is a 3 wire connector on drivers side of the A4LD automatic trans.
1 wire should have 12volts with key on.
Other 2 go to the computer.
One turns on and off the TCC, Converter clutch solenoid
The other turns on and off OD, 3-4 shift solenoid
Check connector, having both solenoids fail at the same time would be a long shot.
But failed 12volts(fuse) or bad connector would explain it.

556 Fuel pump relay primary circuit fault
This would cause engine problems, clear the codes and test again after a few days, if you think you caused it.

565 Canister purge solenoid circuit fault, long shot but could cause engine issue.
In the engine bay usually at the front on the rad support you will find the EVAP canister, larger black plastic box.
It will have two hoses
One will go back to the gas tank
The other one goes to the intake manifold, and has the Purge Solenoid on this hose.
So follow that hose and find the purge solenoid.
It will have a two wire connector.
This is a Vacuum valve, the computer pulses 12volts to it to open valve a little or alot.
Make sure connector is tight.
You can test it by removing connector and apply 12volts to the pins, it will click OPEN and Closed, there is no + or -, it can be hooked up either way.

Engine issue, long shot, if this valve is cracked or its hoses are then that could be an on again and off again vacuum leak, as computer tries to open and close solenoid.

Last edited by RonD; 09-25-2016 at 11:41 AM.
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  #30  
Old 09-24-2016
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Thank you for this information.
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  #31  
Old 09-30-2016
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Hey guys,

I just had an idea proposed to me about my Ranger's problems, and I wanted to get you guys' input.
Could a loose timing chain cause the bogging/sputtering? Could an intermittent change in valve timing cause a bogging scenario?

I think it about has to be a fuel issue (even though I replaced the filter) because it seems to be getting worse, and when I press harder on the accelerator it bogs and cuts out even worse. When I release the pedal, it runs better. Unplugging the IAC doesn't even help anymore (it doesn't stall anymore, just runs really rough and idles really slowly).

Anyway, I just wanted to pass the timing chain idea by you guys.
Thanks!
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  #32  
Old 10-01-2016
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Timing chain on the 4.0 OHV was never a problem, and if the tensioner were to fail you would hear a distinctive rattling noise from the front of the engine.

Would out of time valves cause lack of power, bogging?
Yes, it lowers compression.
Letting off the gas pedal wouldn't change that, the lack of power would be across all RPMs.
It wouldn't cause sputtering.

The "gas pedal" on a fuel injected engine is really an "air pedal".
On a carburetor when you pressed down on the GAS pedal gasoline was actually squirted in to the engine using a mechanical pump(accelerator pump), along with throttle plate opening to let in more air.

With fuel injection pressing down on the AIR pedal just lets in more air as throttle plate opens.
On the throttle plate shaft there is the TPS(throttle position sensor), the TPS tells the computer that the driver has opened throttle plate to let in more air.
Computer then adds more fuel via the fuel injectors.

In order for a gasoline engine to run correctly it needs to have a 14.7:1 air:fuel ratio all the time.
So when you add more air(open throttle plate) more fuel needs to be added instantly or mix will get Lean and lack power.
If too much fuel is added the mix will get Rich and lack power.

From your description of letting off on the gas pedal(letting in LESS air) and engine returning to better power it reads like mix is getting Lean, so either computer is not getting the "message" from TPS or computer is not responding to the "message" to add more fuel.

There is also the MAF sensor involved, a common failure point for the 4.0l OHV engine, clean or replace this.

Also O2 sensors need to be replaced every 150,000 miles, MPG will slowly go down as O2 sensors run out of the chemical used to detect Oxygen, so they do wear out

Last edited by RonD; 10-01-2016 at 11:58 AM.
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  #33  
Old 10-08-2016
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I found out why I was loosing coolant so fast. It was the intake manifold gaskets. After getting those replaced, I was hoping that it might take care of the bogging problem (vacuum leak).

When I first drove it, it ran really smoothly and had decent acceleration, but then a little later it started bogging down and sputtering. At this point I can't even drive it around long enough to get it up to operating temperature so I can get the diagnostic codes.
It seems like it's getting worse.
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  #34  
Old 10-08-2016
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Replaced MAF sensor. Took it out for a drive and was able to go long enough to get it to turn the check engine light on. Ran KOER test, and came up with codes 172 - o2 sensor faults/lean and 136 - O2 sensor fault always lean. Logic tells me that the O2 sensors are bad, but while I was driving around, and while doing the test it had a very noticeable misfire. It seemed like it was only running on 3-4 cylinders. I've checked all the plugs and wires (all tight), and the coil pack is new. I'm not sure what else could be causing it.
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  #35  
Old 10-09-2016
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I replaced the fuel pump relay this afternoon, and it seems to be running a little better. It still bogs down, but now when it does, if I floor it, the transmission kicks down and the engine runs better. What does this mean?
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  #36  
Old 10-09-2016
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O2 sensors wear out at about 100-150k miles

P0172 = Bank 1, sensor 1(passenger side, near engine) is showing Rich even after computer has lowered fuel content

P0136 = Bank 1, sensor 2(O2 sensor after Cat converter) is not responding, usually not hooked up.

O2 sensor tend to fail showing Lean Codes not Rich codes, so long shot on O2 sensor
But if there are over 100k miles on them then good idea to change the 2 front O2s, it will improve MPG.
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  #37  
Old 10-09-2016
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Thank you Ron D.
I'm more concerned about finding the cause of the bogging/misfiring right now. I'll focus on improving gas mileage once I can drive down the road.

I thought I had made some progress today, but I was wrong. It's still bogging and misfiring. I even had it backfire a couple times this afternoon. I'm not sure what else to look for.
Could the fuel pump be causing this? Does this truck have 2 fuel pumps?
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  #38  
Old 10-10-2016
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???

???
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  #39  
Old 10-11-2016
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Boy, this truck must be screwed up. I've stumped the guys on the forums, either that or I've lost their interest
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  #40  
Old 10-11-2016
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Mostly lost interest I think, lol.

No, just one fuel pump, in the tank, and fuel pump issue can't cause bogging.

Back fire(exhaust) is when unburned fuel is ignited in the exhaust manifold, usually comes if you are also having a misfire, thats the unburned fuel.


Bogging is an air/fuel mix problem, all cylinders are firing but engine is sluggish.
In the old days spark timing could also cause that but unlikely with distributorless systems.

Bogging happens within certain RPM range, below that range or above that ranger engine runs fine, which is why it can't be a fuel pump issue
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  #41  
Old 10-12-2016
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Quote:
Originally Posted by Ol' Red View Post
Boy, this truck must be screwed up. I've stumped the guys on the forums, either that or I've lost their interest
Maybe you should replace you O2 sensors, they're probably not functioning that great either.
The problem that blocked up your catalytic converters I'm sure didn't have a very good effect on the O2 sensors, they're probably all sooty and blocked too.
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  #42  
Old 10-29-2016
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I am having all most the same problems as you with the bogging down and such I have been told its the timming chain or gears ,Does this make sence to anyone.
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  #43  
Old 10-30-2016
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4.0l OHV engine never had timing chain issue, that was the 2001 and up 4.0l SOHC engine.

Do a compression test, that will take valve timing off the table as the problem.

Bogging down is usually a MAF sensor issue on the 4.0l OHV
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