Hello,

I have a 2018 Ford Grand C-Max 2.0 TDCI 150hp Titanium (Start-Stop) vehicle. When the start-stop system activates, it turns off the engine without any issues initially. However, when it tries to restart, it struggles, shakes, and feels like it might stall at any moment. Restarting the engine manually resolves the issue. When the engine has been started multiple times, the same problem can occur even during regular driving.

I had the battery tested. The readings are 12.4 volts when the engine is off and 14.1 volts when the engine is running. (I'm almost certain that the battery is older than 2-3 years. According to FordPass records, the last maintenance was done at 180,000 km in 24.04.2022)

A mechanic told me that the injectors and the fuel pump are faulty.

However, the idle is stable, there is no loss of power during acceleration, no misfiring, throttle responses are good. Even with the air conditioning on, it climbs steep hills without struggling. It starts without hesitation even in the morning (although if the engine has been started many times, it may take 1-2 seconds longer to start, but idle remains stable).

The timing belt has been changed, and the oil and filter maintenance have been done recently. (I am not sure if the issue existed before the maintenance as I recently bought the car.)

There are no warning lights on the dashboard, and when connected to a computer, no error codes are found.

What could be causing this problem?

Thank you for your assistance.

If you raise the revs after the restart, does it smooth out, or does it continue to run rough at say 1200rpm?

@TomsFocus No, when I turn off the ignition completely and restart it, there is no problem. Everything is stable, and there are no issues.

Usually, there is nothing wrong on the first start-stop; it runs quite normally. However, on the second start-stop, the engine becomes unstable and does not recover even if I give it gas. To fix the problem, I have to turn off the ignition completely and restart it. After that, there are no issues. 

And sometimes, this problem occurs even when I start the engine back-to-back.

Is there an abnormal noise and vibration in the engine?
The vehicle in the video is mine. I recorded the video to help identify the problem.
The vehicle is running normally here.

 

Hmm, very strange.  I'm not sure what to suggest unfortunately.  I thought it was just low on battery charge after a few starts, my own car raises the revs to around 1000rpm idle after about 3-4 stop/starts in a row.  But if you say adding gas doesn't help yours then it must be a different problem.

Looks fine in the video, diesel engines do vibrate a bit and that gets magnified with the slow frame rate of a camera phone compared to our eyes.

42 minutes ago, TomsFocus said:

Hmm, very strange.  I'm not sure what to suggest unfortunately.  I thought it was just low on battery charge after a few starts, my own car raises the revs to around 1000rpm idle after about 3-4 stop/starts in a row.  But if you say adding gas doesn't help yours then it must be a different problem.

Looks fine in the video, diesel engines do vibrate a bit and that gets magnified with the slow frame rate of a camera phone compared to our eyes.

I suspect that the battery is weak. The problem occurs more frequently after I turn on the air conditioning.

But the mechanic mentioned that the engine is shaking, the sound isn't good, and there might be an issue with the disel pump and injectors, which has left me confused.

But everyone I've shown the video to said that the engine is running as it should. I'll replace the battery and see what happens.