Camshaft and crankshaft sensors

C

carl'slariat

Joined
Jan 10, 2024
Messages
11
My f150 lariat 4wd with 5.4 3v started going into limp mode. Scanner said camshaft position sensor. Replaced the one scanner said. Went into limp mode again. Scanner said crankshaft positioned sensor. Replaced the one scanner said. Still same problem. I then changed oil from havoline 5w30 to Mobil 1 5w20 with a Motorcraft filter and added a quart of Lucas oil stabilizer. Have driven approx. 500 miles with no problem. But my check engine light still pulls code for both the sensors I already installed. Light has been cleared but comes back same.
Do I have to do something else to clear check engine light permanently? And is it OK to continue to use 5w20? I do extra regular oil and filter changes. Thanks for any advice.
 
Is there something that has to be done to computer system for the system to "learn" new sensors?
 
carl'slariat said:
... I then changed oil from havoline 5w30 to Mobil 1 5w20 with a Motorcraft filter and added a quart of Lucas oil stabilizer. Have driven approx. 500 miles with no problem. But my check engine light still pulls code for both the sensors I already installed. Light has been cleared but comes back same.
Do I have to do something else to clear check engine light permanently? And is it OK to continue to use 5w20? I do extra regular oil and filter changes. Thanks for any advice.
Click to expand...

So, you went to a thinner lube (5w-30 to 5w-20), but then added Lucas oil stabilizer, presumably to thicken the oil.
Why? What was your goal in doing this, exactly ?

And what does oil viscosity have to do with the functionality of electronic sensors ? I think you're conflating several topics into one big jumbled question.
 
dnewton3 said:
So, you went to a thinner lube (5w-30 to 5w-20), but then added Lucas oil stabilizer, presumably to thicken the oil.
Why? What was your goal in doing this, exactly ?

And what does oil viscosity have to do with the functionality of electronic sensors ? I think you're conflating several topics into one big jumbled question.
Click to expand...
Cant exactly answer that question. I was to the point of trying anything that was suggested. That was suggested and it worked. It wouldn't have anything to do with the sensors but evidently did have an effect on the cam phasers because it stopped going into limp mode. The Lucas was also recommended and it is also an oil stabilizer if that has anything to do with it. Just needing to know how to clear check engine light. Can clear with scanner but it comes back on.
 
mattd said:
What were the trouble codes exactly? it’s possible you have timing chain stretch issues
Click to expand...
^^^ This.

What code. I think P0340 or something like that is the actual sensors. However P0021 or something on that range is VVT timing - which could be sensors, phasers, actuators or even lower oil pressure. Clean oil seems to sometimes help with the latter.
 
SC Maintenance said:
^^^ This.

What code. I think P0340 or something like that is the actual sensors. However P0021 or something on that range is VVT timing - which could be sensors, phasers, actuators or even lower oil pressure. Clean oil seems to sometimes help with the latter.
Click to expand...
I had someone pull the codes so I personally don't know. I just replaced what he told me to
 
carl'slariat said:
I had someone pull the codes so I personally don't know. I just replaced what he told me to
Click to expand...
If it doesn't come back consider it fixed.

In the meantime buy a cheap code reader, or dongle and app, and learn how to use it - very easy, very cheap. For next time.
 
I'd guess the sensor is fine (either oil), it's the error that the ECU trips over, and how it reports it. The sensor is not sending pulses in the right spot, that's because something else is off, not that the sensor stopped giving pulses back to the ECU. But the error code reporting might just say "go look at the sensor due to implausible reading", and most would think the sensor is bad.

The 5W30, how long had it been in the engine? I'm wondering if it got thin, then the fresh 5W20 (especially with Lucas) was actually thicker. Which somehow resolved something. Sorta... since it's still tossing codes, just not running badly (yet).

Aren't 3V 5.4's the ones with problematic cam phasors?
 
Jimmy_Russells said:
You can't just scan a vehicle, replace said part and expect it to be fixed. The vehicle needs to be diagnosed by someone who knows what they are doing.
Click to expand...
Lots of people (including me) are led to believe wrong then. I thought you could buy a code reader scanner, read the code, look it up, then replace what it said without having to pay a professional high $
 
carl'slariat said:
Lots of people (including me) are led to believe wrong then. I thought you could buy a code reader scanner, read the code, look it up, then replace what it said without having to pay a professional high $
Click to expand...

Sometimes that works, sure, but a lot of the time it doesn't. A scan tool will point someone in the right direction but it's not as simple as point and shoot.
 
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