8

My cousin told me when he enter his car, he put the key to ignition then count to 3 and start the engine.

The main reason of him doing that is to give enough time to fluids (I'm not sure which one) to fill to the engine (I'm skeptic, need more info on this).

He told me that in "ze good ol'days", car would sometimes fail to start if you directly turn the key to start engine and that even if they does start now, it is still better for the engine to wait a few seconds.

This seems logical (although I doubt it's really something we should matter).

Why is it better to wait a few seconds at ignition position before starting the engine?

10

The only type of vehicle you need wait on is a diesel powered one. The reason for that is you need to wait (in most of them) for the glow plugs to heat the combustion chamber. Modern fuel injected cars will keep their fuel pressure after shutdown. It will stay there (usually) for a good 24 hours (Note: 24 hours is an approximation. It will take longer in some cars and less time in others for the fuel pressure to bleed off back into the fuel tank). When you turn the key on, the fuel pump will start running. This happens as fast as you turn the key. Oil doesn't start flowing until the engine is actually running, so if you tried to wait for that, you'd be waiting a lot longer than three seconds.

Even with non-fuel injected cars there are no worries. In many older non-fuel injected cars, fuel pressure is not delivered until after the engine is turning over, so no sense in waiting for this to happen either. Cars with carburetors will continue to have fuel in their fuel bowls, so has a ready supply of fuel.

Bottom line, I guess is this: it doesn't hurt anything to wait the three seconds, but you aren't creating any issues by not waiting. There will be no long term effects from starting it right after key insertion.

  • 1
    Another thing to add is that waiting on diesels is not required when the temperature is above ~5°C as the glow plugs shouldn't activate. Also, while in perfect conditions you are correct, older cars won't keep the pressure for so long. My car, for example, won't keep full pressure for more than an hour. And some cars will have a harder time starting if you try to start immediately without waiting at least a bit of the priming period, until pressure is accumulated. – I have no idea what I'm doing Jul 14 '16 at 9:06
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    I'd also like to add that some cars start the fuel pump when the doors are unlocked and/or when the driver's door is opened. So another reason not to wait. – juhist Jan 8 '18 at 14:59
5

I used to do this with my Ford Fiesta and Puma - it's all about fuel. When the ignition key is turned on, the fuel pump runs for a few seconds, then shuts off. This ensures there is enough fuel pressure in the rail to start (since a richer mixture is required to start when cold). The Puma did not like me turning the key straight to START without waiting for the pump to run; it would cough a few times and stall. Letting the pump add pressure would ensure a perfect start each time. The smaller Fiesta engine (same series as the Puma) didn't seem to mind starting straight from OFF.

As @Paulster2 noted, modern fuel-injected cars maintain pressure at the rail for a long time, both making starting quicker, and maintenance more time-consuming! Most current injection systems do not return unused fuel to the tank, so the pump will only run to bring the pressure up to operation. My general rule is that, if you turn the ignition ON and there's a soft buzzing noise, wait for that to shut off before starting the engine. If it doesn't, you can start it without waiting. My 1985 Supra only runs the fuel pump when the key is turned to START (and once the engine is confirmed running) so there is no need to wait at ON for anything to happen before cranking the engine.

1

My '98 Honda Accord will on rare occasions fail to turn over if I turn the key immediately after entering the car and putting the key in the ignition. I believe this happens because the car's computer wants to talk to the key (it's an anti-theft measure), and the computer sometimes doesn't get the "OK" from the key by the time I turn it.

When this happens, I remove the key, put it back in, wait a bit, and turn it. It starts.

Most of the time, however, it works fine without having to wait or remove the key or whatever.

0

On my 1998 Sable I had some problems starting when it was very cold. I dreaded this very cold snap (low single digits) would be a pain as last year I had to jump my car twice when the temps were in the teens. Someone suggested to wait in the on position a few seconds. For me it was a godsend, I don't care about why, I just know it worked.

protected by Pᴀᴜʟsᴛᴇʀ2 Jan 8 '18 at 15:02

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