Knocking and stalling only when engine has warmed up

2006 FORD F-150
168,900 MILES • 5.4L • V8 • 4WD • AUTOMATIC
Avatar
CHRESTIAN WALKER
  • MEMBER
  • 4 POSTS
I having a issue with my truck it will run fine when it is cool and just starting and then the engine warms up and sometimes starts knocking really loud. Then the truck will stall at a complete stop. There is no check engine light on and no code coming up and I don't know why would the crankshaft sensor cause this? Also, I have another question. I had my A/C compressor replaced and the guy hooked it up and now it just keeps blowing fuses when I turn it on. any idea what this could be? please help!
Sep 18, 2020 at 2:29 PM
Advertisement
Avatar
JACOBANDNICKOLAS
  • Experienced Mechanic
  • 110,240 POSTS
It sounds like a short. Check the wiring at the compressor to make sure nothing is pinched or damaged.

As far as the engine, the stalling when warm does sound like a crankshaft position sensor, but the knocking usually isn't associated with it.

Take a look through this link and let me know if you feel it mirrors what you experience:

https://www.2carpros.com/articles/symptoms-of-a-bad-crankshaft-sensor

Also, if you could record the knocking so I can hear it, it may be helpful.

Let me know.

Joe
Apr 26, 2021 at 5:55 AM
Avatar
BMDOUBLE
  • Experienced Mechanic
  • 1,139 POSTS
An oil pressure test would be a good idea, but these engines are known for the knocking sound coming from either the cam phasers or rod bearings, root cause sometimes being lack of maintenance like oil changes, but I've seen engines with less than two thousand miles make knocking noises. On this engine, never ever go more than five thousand miles between oil changes! https://www.2carpros.com/articles/high-or-low-engine-oil-pressure
Apr 26, 2021 at 5:55 AM
Avatar
STRAILER
  • Experienced Mechanic
  • 55,325 POSTS
Can you please shoot a quick video with your phone so we can hear the noise? that would be great. You can upload it here with your response.
Apr 26, 2021 at 5:55 AM
Avatar
CHRESTIAN WALKER
  • MEMBER
  • 4 POSTS
I got my A/C to work but still have issues with my truck. I ran the scanner on my truck and it says system pass no faults detected but when I look under pending codes I get P0340 and P0344 camshaft position sensor bank 1 cut a. one says malfunction and then the other says intermittent. does that mean I should change the cam shaft position sensor on my truck and it should be okay or what? you all decide. please let me know I really need to get my truck fixed so I can get back to work on Monday morning. again there is no check engine light coming on on my truck at all, but that’s what my Actron scanner is saying under pending codes, but diagnostic code it says system pass no faults detected. can the cam shaft position sensor cause my car to start knocking and stall?
Apr 26, 2021 at 5:55 AM
Avatar
JACOBANDNICKOLAS
  • Experienced Mechanic
  • 110,240 POSTS
Pending codes are set when intermittent faults happen and the PCM needs to see happen consecutively.

The codes you have are slightly different. The P0340 indicates the PCM is intermittently getting a signal from the cam sensor and the P0344 indicates no signal.

With that in mind, I would check the connections at the sensors to confirm they are clean, tight, not corroded, and not damaged.

As far as causing knocking, anything is possible, but when there is no signal, it should go into a default setting. However, anything that has a partial control over timing can cause issues.

Let me know.

Joe
Apr 26, 2021 at 5:55 AM
Join 2CarPros for free, one of the most advanced car repair communities on the internet. From first-time drivers to seasoned mechanics, everyone is welcome to reply, share details, and get better answers. You can add a temporary image or video first; uploads are limited to 20 MB.
Ask a Free Question
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.