Question: I have a 2016 Ford F150 with the 2.7-litre EcoBoost engine. The truck has an Auto Start-Stop feature that turns off the engine sometimes when I come to a stop. Most of the time, this seems to work fine, but occasionally it seems to jerk as the motor restarts. Should I be concerned?
Answer: Auto Start-Stop is a feature found on many newer vehicles. On your truck, the Auto Start-Stop feature should be functioning all the time, except when in 4x4 mode or Tow mode.
The engine will automatically stop running when the vehicle is stopped if certain conditions are met. These include having the engine at normal operating temperature, the passenger compartment at a comfortable temperature, the vehicle stopped and the driver’s foot on the brake pedal.
Sometimes the system may not turn the engine off, but this is usually due to either the engine or passenger compartment not at normal temperatures.
I have experienced the “jerk” feel you describe on several different makes of automobiles. It only occurs occasionally and typically happens if you come to a stop and then quickly start to go again.
The engine is in the process of stopping but then suddenly restarts before it has completely stopped. The jerk is a result of the engine torque and the transmission taking up clearance in the drivetrain very suddenly.
It hasn’t caused any problems and occurs rarely, so I wouldn’t worry about it.
Question: I have a 2011 Toyota Corolla with an automatic transmission.
At 24,672 kilometres in 2012, the check engine light came on and when I took it to the dealer, they said there was too much gas in my fourth engine cylinder and a code was set for misfire.
In 2013, this happened again with misfire codes P0300, P0302, P0303 and P0304 set for misfire. The codes were cleared and all was OK.
My problem now is when I go to start my car, I turn the key and it cranks for a long time before it starts.
The problem is getting worse. I took it to the dealer and when they checked it out they couldn’t find anything because the problem wasn’t occurring at that time.
The car now has 105,000 km on it and I am getting scared to drive it. Help please.
Answer: I doubt if the current problem is related to the previous misfire codes because of the mileage and time difference between problems.
Misfires are typically caused by a bad spark plug or plug wire, a dirty or leaking fuel injector or a vacuum leak.
While these problems can cause extended cranking and hard starting, I suspect the problem is something else.
You do not say whether the vehicle runs fine when it has started, so I will assume it operates normally after getting started. This would rule out the faults mentioned above.
Instead, the problem could be with low fuel pressure during cranking.
When you turn the key to the “run” position, the fuel pump should run for a couple seconds and will then stop. You can hear this if you listen at the fuel filler as someone turns the key.
As you start the engine, the fuel pump will run again continuously and continue to do so when the engine starts.
During cranking, much of the battery energy is directed to the starter motor, so system voltage drops from the 12.6 volts of a fully charged battery down to about 10 volts.
The lower voltage may cause a weak fuel pump to not operate or operate more slowly, so fuel pressure is lower than normal.
Proper fuel pressure during cranking is critical to engine starting. On some engines, even a drop in pressure of two per cent can cause extended cranking and hard starting.
On your Toyota, the drop in pressure may be even more.
Because the problem is only there during starting, you may need to leave the vehicle at the dealership and have them test the fuel pressure after the vehicle sits overnight.
They need to check pressure while the engine is cranking.
If it is low, then the electrical connections to the fuel pump should be checked to ensure they are clean and tight, but in most cases the problem is in the fuel pump itself.
To change the fuel pump in your car, there is an access cover on the rear floor that allows access to the fuel pump.
On many vehicles, the tank must be removed to access the fuel pump, but not on your Corolla.