Cold Flood engine start mode (eg. Mopar)

[shogun32]

Apparently on Mopar trucks (5.7 hemi) but perhaps across the lineup, flooring the gas and cranking the engine causes the engine to turn over but spark and gas is shut off. Basically it's a cold crank. Does Ford (or GM) have something similar? Seems like a perfect thing to do after an oil change (primes everything) or in the aftermath of an "engine event" where you might want to spin the engine but don't want it to actually fire.

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[OU81]

Not sure on Ford or GM but can confirm the 5.7 Ram does it. I had a 2016 Ram R/t that would have bad dry starts if you let it sit for a few days. I started doing this & it would eliminate all the dry start clatter. I would just crank it with the gas to the floor for about 10 seconds, let off then crank.

 

[BmacIL]

Yes, can confirm the S550 will.

 

[EFI]

Yes, can confirm the S550 will.

How long can you do this for, indefinitely?

 

[BmacIL]

How long can you do this for, indefinitely?

Well, it's not great for the battery or starter after a while...and don't know how long it can go before it stops.

 

[EFI]

Well, it's not great for the battery or starter after a while...and don't know how long it can go before it stops.

Is it any different really than unplugging the coil packs and fuel pump?

Most people that are installing a new engine would be doing this anyway, and I can't imagine that a car that is used even semi-regularly would need this. Maybe if you haven't started the engine in a few years it's a good idea.

But the oil filter has an anti-drainback valve and the pump doesn't bleed oil so an engine should see oil almost instantly after starting normally.

 

[Bartly]

Is it any different really than unplugging the coil packs and fuel pump?

...

You have me wondering if this would be a good alternative to inputting the fuel pump connector when removing the injectors. Anyone done this? Does it drain the pressure as much as unplugging the fuel pump?

 

[Slopoke]

If it's anything like a Fiesta ST. Just hold the clutch and gas pedal down, push the start button and it'll crank for a few seconds and then stop by itself. Good to do when priming a new turbo with oil. Just don't let off of the gas, from what I understand, it'll start. Never tried it to find out though.

 

[CrashOverride]

You have me wondering if this would be a good alternative to inputting the fuel pump connector when removing the injectors. Anyone done this? Does it drain the pressure as much as unplugging the fuel pump?

It's not going to do anything with the fuel pressure - it tells the ECM not to open the injectors and not to fire the coils when cranking. I am not positive, but I think the fuel pump still primes the system because it's (partially) designed to help you start the car if it's flooded and you will need the fuel pump running when you let off the gas whilst cranking.

I also believe the throttle body opens all the way.

Another great use for this is when doing a compression test. Anytime you don't have to pull connectors is a good thing in my book. Less plastic to break, less chance of a bad connection if not reassembled properly.

 

[Bartly]

It's not going to do anything with the fuel pressure - it tells the ECM not to open the injectors and not to fire the coils when cranking. I am not positive, but I think the fuel pump still primes the system because it's (partially) designed to help you start the car if it's flooded and you will need the fuel pump running when you let off the gas whilst cranking.

I also believe the throttle body opens all the way.

Another great use for this is when doing a compression test. Anytime you don't have to pull connectors is a good thing in my book. Less plastic to break, less chance of a bad connection if not reassembled properly.

Thanks for the info.

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