A while back I noticed the race car engines at a local track didn't start as quick as they used to.I thought it was strange because they get better all the time.I told a friend and he said that's because they don't turn the ignition on until the oil pressure comes up.What I'm wondering is are new cars doing the same thing?My wife's car turns over a few times before starting.Yesterday a friend started his truck and it turned over a long time before starting.I asked him few questions and wouldn't you know it he said it stared up a lot faster in the winter.When the oil is thicker.Just wondering.
railguy

 

Many years ago the British Rover SD1 had an interlock between the oil pressure switch and ignition circuit. No spark until it had 5 lbs pressure.
One side effect was if the battery was a bit off it probably wouldn't start. often the owners would have the system removed, Rovers were unreliable enough without more to go wrong!.


Roger.

 

Most modern computer controlled cars wait for a certain number of pulses or revolutions from the cam and crank sensors before firing the ignition.
Nothing I have waits for oil pressure.

- Eric

 

That makes sense, I guess the ecu needs enough information to determine the crank and camshaft position before it can decide when to fire the ignition and how much fuel to deliver.


Roger.