I cleaned the air intake spraying a Sonax liquid air intake cleaner. I took off the air filter, sprayed, waited to get dry and started the engine. It works well in my car that I think it was clean before because it has 20.000 km (around 12500 miles). I did the same process later in a friend's car, but the engine didn't start quickly. I needed to push the accelerator pedal for some seconds while trying to start the engine. Why it didn't started instantly? Maybe the liquid didn't complete dry? Maybe the intake was too dirty?