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Discussion Starter · #1 ·
We noticed that the engine start button must be pressed 2-3 seconds before the engine fires... and then runs normally. Our new C7 Z51 Stingray does not start with a brief push on the start button like our C6. The battery is new and indicates fully charged (checked with a Optima charger). Are other owners of new C7's also noticing slow starts?
 

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I have read that some other C-6 owners have made the same observation about their C-7, but not a lot.(yet)
 

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I just press and release it once it starts to turn over. In the mornings it takes a few second due to coldness, but in the afternoons it starts right up.
 

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It's been my experience with the last 4 cars I've owned, whether they are push button start or look to have a real key, is you can let go of the button / key the moment you hear the starter motor and the car will keep turning over until it starts. On my 2014 Silverado, which has the same basic electronics, on colder mornings it takes about 3 seconds to start, normally it's virtually instant. It wasn't until the first cold morning after the truck sat for a few days was it obvious it was cranking without me holding the key in the start position.

So, just press and release the button and see what happens.
 
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The initial start in the morning have been lengthy. I have been accustumed to the push of the button and toar of the motor. I've thought it was the due to the direct inject fuel system coming up to pressure. Im sure this condition doesn't exist on the C7R.
 

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I look at it as getting a few revolutions on the oil pump to get some oil into the bearings before hitting them with a load. Should help eliminate/reduce startup wear.
 

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It's all electronic now...with start up sequencers just like your computer at home. You don't "start' the starter like you used to, you initiate the systems by just closing a circuit. (the start button)
 

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Mine does it too. I also think it may be because it's cold in the morning. But I'm in CA. so I doubt it. Maybe after sitting for 12 hrs something happens. , but granatelli makes 0 ohm ignition wires that replace the stock ones which are significantly higher. It also adds 13hp. So I'm assuming the restricting stock wires have something to do with it.
 
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Discussion Starter · #10 ·
I think my problem was misstated, and I apologize. I understand the START button only needs to be pushed briefly to start the engine, not held down for 2-3 seconds until it fires. The problem is after pushing the START button, the engine cranks for several seconds before starting, and this is not the way my '08 started or any of my other cars start. Once again, the battery is strong so I know it not that.
 

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My wife's 2014 Cadillac also has a new engine with direct fuel injection and variable valve timing. It cranks several seconds before it gets going. These new ones seem to take a long time compared to the engines from years ago which would fire up in less than a half second. As far as I know, this is perfectly normal.

Can anyone else confirm what their engines do?
 

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Mine does it too. Push the button and it cranks a few times before firing. Seems to be normal. May be either a delay in start to circulate the oil, or something to do with the direct injection.
 

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The more I think about it the more I lean towards a check in the software the doesn't trigger the fuel injectors until some minimum fuel pressure is reached to be certain you don't back flow the injectors with cylinder pressure higher than fuel pressure. Add to that a mechanically driven pump driven off the camshaft which spins at 50% of engine rpm, you'll have a few revolutions of the engine to get up to minimum pressure when cold and all of the residual pressure has bleed off from sitting.

Just thinking out loud on this as I have no real data to support my thoughts.
 
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Direct injection requires the engine to turn over a few rotations to build the appropriate pressure.
 

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I have the exact same thing going on. My C6 starts as soon as I hit the button and the C7 takes a few seconds hot or cold. I will taking it to the dealer this week for a seat heating issue as well as an issue with the "auto" selection on the AC. Maybe I can get some feedback from the technician.
 

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GM explains extended crank times on our Stingrays

From GM TECHLINK Extended Cold Crank with Direct Injected Engines

The 4.3L, 5.3L, and 6.2L (RPOs LV3, L83, L86 and LT1) direct injected (DI) engines available on some 2014-2015 Corvette, Silverado 1500, Suburban, Tahoe, Sierra 1500 and Yukon models may have an extended or long crank time during cold ambient air temperatures.
Direct Injection engines may have slightly longer cold crank times than that of port fuel injected engines. Direct Injection systems run at higher pressures and the mechanical pump on the engine must build up the required pressure before the first injection event occurs.
Following are typical DI engine crank times using gasoline:
engine crank.jpg

If the temperature is below -22°F (-30°C), the recommendation is to perform an assisted start (such as with the use of a block heater).
 

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This is why I love this forum and I don't even have a C7 yet.


Sent from my iPhone using Corvette Stingray Forum
 
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