On 6/25/2024 at 9:21 PM, unofix said:

Very probably. Get the cluster refurbished. 

@rd457

Unfortunately, after the cluster repair, it is still the same. The problem did not go away. I did try cleaning with contact cleaner, but it is still the same.

 

When I start my car, it is rough and goes up to 3000 rpm. When I drive slowly, the limit speed mode is on. The engine is so rough. My car engine idled rough at stoplights and stalls only while stopped. The speed limit mode and the engine feel rough if I drive slowly around the city, and I need to restart the car constantly to fix this problem. But the engine is less rough if I drive at high speed, around 40 to 60 miles per hour.

 

The worst is that after a few more tries these few days, my car battery is dead. I jump-started with another car, and the ForScan list is even longer now. I'm just curious. Will this resolve all the issues if I replace my battery? Since the following is already done: -

• Clean throttle body (My mechanic replaced the new aftermarket throttle body, but the problem persists)
• Changed the spark plugs
• Changed the air filter and cabin filter
• Replaced the Intake Manifold Vacuum Solenoid Valve
• Bad solder joints on Ford vehicle Instrument Clusters had been fixed by professional

25 minutes ago, M Lam said:

Will this resolve all the issues if I replace my battery?

A new fully charged battery will most likely solve a good many of the faults. You will need to clear all the the DTC's using FORScan.

It certainly seems that there is an issue with the Canbus with "Ux xxx" codes. Possibly a loose or damaged connector. Have you tried charging your battery for at least 12 hours, clearing the codes and see what comes back?

1 hour ago, unofix said:

A new fully charged battery will most likely solve a good many of the faults. You will need to clear all the the DTC's using FORScan.

It certainly seems that there is an issue with the Canbus with "Ux xxx" codes. Possibly a loose or damaged connector. Have you tried charging your battery for at least 12 hours, clearing the codes and see what comes back?

Good one. After resetting, the U1900 error and all others are gone. 
I guess the only problem is either

•  Leaks in the air induction system
•  Faulty or damaged PCM (Power train control module)

On 7/5/2024 at 9:15 PM, unofix said:

A new fully charged battery will most likely solve a good many of the faults. You will need to clear all the the DTC's using FORScan.

It certainly seems that there is an issue with the Canbus with "Ux xxx" codes. Possibly a loose or damaged connector. Have you tried charging your battery for at least 12 hours, clearing the codes and see what comes back?

I heard there are basic tricks for determining whether I have a vacuum leak using Forscan.

• graph the LTFT 1 and 2
• graph engine RPM
• graph the STFT 1 and 2

I let the engine warm up, say 5mins, because it needs to be in a closed loop for the fuel trims to be correct and active.

Then, I rev my engine (or increase rpm to 3k) and see if the fuel trim graph goes up or down.

If the fuel trim graph goes down at high rpm (3k above) or shoots up at idle (low rpm), I have a vacuum leak.

I just investigate further and I just found my graph is interesting

• (STFT2) Short-term fuel trim 2 is always still 32.81%
• (STFT1) Short-term fuel trim goes down at high rpm (3k above) or shoots up at idle (low rpm)

Any idea? Does it mean my car have multiple issues?

@Tizer@Tizer  is probably the one who can best answer the questions, he has more knowledge about this when it comes to FORScan live data.

I have never tried to trace a Vacuum leak electronically. I tend to use the traditional method so I'm not sure if the readings you have are conclusive or not.

I would expect there to be some Codes for Fuel Trim if there was a leak though.