2008 Ford F-150 5.4L - Crank, No Start
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Customer Complaint: This truck came in with a complaint that it would sometimes not start and when driving down the road it, it would go into limp (low power) mode.
Information: From closer observation, it can be seen that this engine is not the original engine. After questioning the owner, it was revealed that the engine had been replaced a few weeks before before he bought the truck. With this information, it leads me to believe that there may be an installation issue from when the engine was installed.
Diagnostics: The first thing I wanted to do was see what codes were stored in the truck. They are displayed below.
I decided to chase after the first two codes on this list: P0320 and P061C.
With these codes, it seems the engine has a problem with sensing the engine speed. If the ECM (Engine Control Module) does not know how fast the engine is turning, then that will definitely cause a problem.
At the time of gathering these codes, the truck would not start for me. On most vehicles, if the ECM is receiving a signal from the CKP (Crankshaft Position Sensor) it’ll show on the tachometer while cranking. You will see the tachometer flickering up and down as the engine is cranking.
I noticed the tachometer on this truck was not flickering as it was cranking. So I decided to see if the ECM was receiving a signal by looking at the live data.
I’m using a scanner called the Zeus made by Snap-On. It is an advanced scan tool that can capture data quickly and in real time. I have noticed that on less advanced scan tools, it may lag when receiving data. So when monitoring data, like the RPMs, on a less advanced scan tool, give it a second or two to receive data. If the data is not instantaneous due to lag, it may seem like you have an issue with the crank signal when you do not.
Overall, give any scan tool time to collect data, because they may have lag in receiving data.
As you can see from the data above, I do not have a crank signal. The engine is clearly turning because the MAF (Mass Airflow Sensor) is showing a rush of air being pulled into the engine.
There is either a problem with:
The CKP - Crankshaft Position Sensor
Wiring issue between the CKP and ECM
The ECM
The first two on the list are the most likely and it can equality be either one of them at this point, because of one piece of information.
We know from the customer that the engine has been replaced.
The CKP could have been damaged or the wiring could have been damaged. The next step is to do a visual inspection.
Doing a quick visual inspection revealed the culprit.
The CPK lives right next to the A/C compressor on this truck. You can see it in the picture above.
I noticed that the sensor’s connector did not seem to sit all the way on the sensor. I gave it a slight tug and it popped right off the sensor, indicating that it was not plugged in correctly.
I tried to push it on fully but it would not snap into the sensor. There is something wrong with the connector on this truck. I plugged it in the best I could so that I could drive it into the shop to replace it.
The connector for the crankshaft position sensor was full of dirt and the rubber o-ring inside of it was destroyed and keeping the connector from correctly plugging into the sensor.
After replacing the connector, the truck fired right up and did not have any trouble starting or going into limp (low power) mode. Fixed!
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