Car slow to start and high fuel consumption on idle

Slayer92
Wed, 22 Sep 2021 12:16:18 +0000
Maintenance/Repairs

Hello,
My diesel car is slow to start in the morning AND when I let the car sit for hours even if its really hot outside.It takes about 4 seconds after I press the START button for the engine to start.
Only when I start the car minutes after I turned the engine off,it starts imediattely.
Another problem I face is a really high fuel consumption on idle.It shows about 20 Litres/100km although when I drive it ,the fuel consumption is normal (4l/100km on highway)
Other than than,I dont have any fault lights on the dashbord and my car drives fine.
I used a car scanner app and no trouble codes were found,no missfires ,although when I investigated some sensors I found some strange values when the car was stationary with the engine turned on:

MAF air flow rate:11 grams/second
Throttle position: 59%
Fuel rail pressure: 3500-4000 psi
turbocharging pressure: 990 mbar
rail pressure: 260 bar
hydraulic unit temperature: 0 degress Celsius

I did some research and what strikes me most is why the throttle position is at 59% on idle when i dont touch the gas pedal?I will try to make a test with gas pedal close to the ground and see the difference.
Regards,

18 posts - 8 participants