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Need help diagnosing a problem I’ve had for 3 months


JodyTanner93

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Hey guys I just signed up to see if anyone could point me in the right direction with my truck. I’ll start from the beginning when I bought it about 3 months ago. I’ve got a 2006 Ford Ranger xlt 2wd automatic with the 3.0 Vulcan engine. So when I first purchased the truck it ran perfect and I had no issues other that the ac compressor would not kick on, even after recharging with refrigerant. About 3 days later the check engine light comes on and there’s a slight hesitation and rpm dip when pushing the accelerator. At this point it still drives fine but I get the codes checked and they say lean condition bank 1 and 2. Also say cat system efficiency below threshold. A month into driving it and an intermittent knocking starts and continues to get worse over two weeks. Also at this point the blower motor starts to go out and after week won’t work at all. Next thing I do is get the engine replaced with a remanufactured one because one of the bearings went out and bent/stretched a rod on the old one. So after the engine swap the hesitation and cel is still there so I search for vacuum leaks but can’t find any. I’ve replaced the maf sensor, throttle positioning sensor, driver side valve cover & gasket (due to a crack) and after the maf sensor replacement the cel hasn’t come back on in a week. Problem is the hesitation is still there and even worse now. If I don’t lightly feather the throttle and ease into it from a dead stop it’s a 50/50 shot it will stall. I’ve tried to search but cannot find any more info. Thanks in advance for any help or direction anyone could give me.
 


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19Walt93

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Did you adjust the TP sensor or just bolt it on? The signal return should show as close to 1 volt as you can get it at idle. One wire will have about 5 volts, one is ground, the other is signal return and you adjust it by slightly loosening the screws and turning the sensor back and forth.A change of .2 volts makes a huge difference.
 

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Welcome to TRS :)

So you have a new/rebuilt 3.0l Vulcan engine in 2006 Ranger
No codes but a hesitation when starting off

After engine is warmed up and idling, unplug the 2 wire connector on IAC Valve
Idle should drop to 500rpms(barely running) or engine may stall, either is GOOD, it means no vacuum leaks
If idle doesn't drop then there is a vacuum leak, or as said above TPS is holding throttle open too far

There is a screw on the throttle linkage, its the anti-diesel screw, NOT an idle screw because everyone knows there can't be an idle screw on fuel injected engines, there are no idler jets
If you have adjusted this screw then you will need to reset it, IF...........it was causing the higher idle with IAC Valve unplugged
This screw can also be used to adjust TPS voltage, slightly, to get it below 1v when throttle is closed


The TPS can cause the describe hesitation, its main purpose is to prevent that hesitation when starting off
When you press down on the gas pedal the computer needs to spray extra fuel in in response to the extra air
The MAF sensor is too far away to give the computer the instant "heads up" that extra air is being added
So thats what the TPS is there for, instant feedback to computer to add that extra fuel, without that there would be hesitation

On a carb engine the "accelerator pump" did that same job, squirted in extra fuel as throttle opened to prevent the hesitation
 

JodyTanner93

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Did you adjust the TP sensor or just bolt it on? The signal return should show as close to 1 volt as you can get it at idle. One wire will have about 5 volts, one is ground, the other is signal return and you adjust it by slightly loosening the screws and turning the sensor back and forth.A change of .2 volts makes a huge difference.
I had a shop replace that so I’m not sure if they adjusted it or not. I will have to check with a multimeter and report back
 

JodyTanner93

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Welcome to TRS :)

So you have a new/rebuilt 3.0l Vulcan engine in 2006 Ranger
No codes but a hesitation when starting off

After engine is warmed up and idling, unplug the 2 wire connector on IAC Valve
Idle should drop to 500rpms(barely running) or engine may stall, either is GOOD, it means no vacuum leaks
If idle doesn't drop then there is a vacuum leak, or as said above TPS is holding throttle open too far

There is a screw on the throttle linkage, its the anti-diesel screw, NOT an idle screw because everyone knows there can't be an idle screw on fuel injected engines, there are no idler jets
If you have adjusted this screw then you will need to reset it, IF...........it was causing the higher idle with IAC Valve unplugged
This screw can also be used to adjust TPS voltage, slightly, to get it below 1v when throttle is closed


The TPS can cause the describe hesitation, its main purpose is to prevent that hesitation when starting off
When you press down on the gas pedal the computer needs to spray extra fuel in in response to the extra air
The MAF sensor is too far away to give the computer the instant "heads up" that extra air is being added
So thats what the TPS is there for, instant feedback to computer to add that extra fuel, without that there would be hesitation

On a carb engine the "accelerator pump" did that same job, squirted in extra fuel as throttle opened to prevent the hesitation
Thank you for the detailed information. I have tested unplugging the IAC and the truck does drop to 500rpm. Do you think the actual IAC could cause these problems? I feel like I hear a hissing that increases with engine revs coming from the upper intake or underneath. Maybe it’s just engine noise but it sounds like hissing to me.
 

rusty ol ranger

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Thank you for the detailed information. I have tested unplugging the IAC and the truck does drop to 500rpm. Do you think the actual IAC could cause these problems? I feel like I hear a hissing that increases with engine revs coming from the upper intake or underneath. Maybe it’s just engine noise but it sounds like hissing to me.
IAC wont cause it to stall on accleration.

Either you got a fuel pressure problem or a vacuum leak.

Has the fuel filter ever been changed?
 

RonD

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Is PCV Valve new?
 

JodyTanner93

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IAC wont cause it to stall on accleration.

Either you got a fuel pressure problem or a vacuum leak.

Has the fuel filter ever been changed?
Fuel filter was replaced about a week ago and was dirty. I am trying to borrow a fuel pressure to test. Where can I find psi rangers to compare with?
 

RonD

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1997 and earlier Rangers used 35psi fuel pressure
1998 and up Rangers use 55psi fuel pressure

But not sure it could be fuel pressure related if you can drive at highway speeds with no issues

I would test the voltages on TPS, or get a Bluetooth OBD2 reader and see whats happening with ALL the sensors when hesitation occurs
Bluetooth OBD2 reader is under $20 and works on ANY vehicle 1996 and up, so not a Ford thing
APPs are free or $5

It could ultimately be a computer issue, so an exercise in "tail chasing" until thats the only thing left, lol
 

JodyTanner93

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Is PCV Valve new?
It is the ribbed one that looks heavy duty. I didn’t see any cracks or splits. I’ve tried spraying brake cleaner around and did not notice and increase in rpms.
 

JodyTanner93

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1997 and earlier Rangers used 35psi fuel pressure
1998 and up Rangers use 55psi fuel pressure

But not sure it could be fuel pressure related if you can drive at highway speeds with no issues

I would test the voltages on TPS, or get a Bluetooth OBD2 reader and see whats happening with ALL the sensors when hesitation occurs
Bluetooth OBD2 reader is under $20 and works on ANY vehicle 1996 and up, so not a Ford thing
APPs are free or $5

It could ultimately be a computer issue, so an exercise in "tail chasing" until thats the only thing left, lol
My buddy has one. I’ll see if I can use it and post the results today or maybe tomorrow. I took a video earlier. I will post the link.
 

RonD

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Watched video

Still voting TPS as it looks like a delay in air/fuel mix changing to Rich
Although I would expect to hear pinging during hesitation from the lean mix, which I didn't hear

Do you have the same hesitation when engine is cold and idle is higher?
Computer runs Choke mode just after cold start, which is richer air/fuel mix, higher idle and different spark timing


Your 650rpm idle seems a bit low for a 2006 3.0l, would expect 750 and then 800 in gear(or AC on)
Not that that's the problem, but could be, more of a curiosity of why the computer would have 650 as target warm engine idle, that's what manual transmissions idle at

PCV Valve is a vacuum activated valve, but in reverse
When throttle is closed the weighed valve inside the PVC is sucked up, closing it, when throttle is opened the vacuum drops but PCV Valve should just drop a little, if it is falling completely open that could add too much air, causing the hesitation
You could plug the PCV Valve hose taking it out of the picture, just as a test, its a longshot but not a no shot, lol
 

JodyTanner93

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Watched video

Still voting TPS as it looks like a delay in air/fuel mix changing to Rich
Although I would expect to hear pinging during hesitation from the lean mix, which I didn't hear

Do you have the same hesitation when engine is cold and idle is higher?
Computer runs Choke mode just after cold start, which is richer air/fuel mix, higher idle and different spark timing


Your 650rpm idle seems a bit low for a 2006 3.0l, would expect 750 and then 800 in gear(or AC on)
Not that that's the problem, but could be, more of a curiosity of why the computer would have 650 as target warm engine idle, that's what manual transmissions idle at

PCV Valve is a vacuum activated valve, but in reverse
When throttle is closed the weighed valve inside the PVC is sucked up, closing it, when throttle is opened the vacuum drops but PCV Valve should just drop a little, if it is falling completely open that could add too much air, causing the hesitation
You could plug the PCV Valve hose taking it out of the picture, just as a test, its a longshot but not a no shot, lol
It runs a lot better and is more responsive after a cold start but when it warms up it runs like crap. The hesitation is still there but a lot less prominent also. I’ve taken it in 3 times and nobody can tell me what’s wrong with it.
 


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