dans15z06

I posted this in the C7 section and since found out that there is a Z06 section.
I would like to know if anyone else has this problem with their C7 Z06.
After it sits over night in the garage when I start it up it turns over 8 to 12 times before it starts. And when cold at idle it is running a little rough. If I sit in the car as it is warming up I can feel a miss. I know this isn't right because a friend has a 2015 Z06 8 spd auto just like mine and it does not do this. My dealer says it is OK and I know that it isn't. Anyone have any ideas?
Dan

mdz06vetter

sounds normal to me

bunch3131

I'm sure someone else much more knowledgeable will chime in with the specifics because this topic has been covered here before, but apparently it is quite normal. The fuel pressure in our engines is quite high and it can take some time to come up to pressure after the car has been sitting for a while.

DocDavid

My new Z06 A8 also takes some cranks before engine catches. My guess would be that the fuel pump has to get some gas in the lines before it catches. Once its hits, the car starts right up.
My 2002 Z06 also took some time, unless I allowed the fuel pump to fill the lines before cranking. That was possible to do in the old days!

Calif Vetteman

Is the fuel pump in the Z, electric ? Would just turning on the acc. mode start the fuel pump before starting ?

dans15z06

A friend has a 2015 Z06 and he says it starts up immediately after an overnight cool down.
Maybe he is just lucky. Anyway the dealer is going to look at it again next week. I will insist they check for codes.
Thanks for the input.
Dan

mjpcowboy

Mine does the exact thing I don't think anything is wrong based on your description

Classic-Chevy-Guy

I had a similar problem on my 2004 Convertible. There was a O-ring in the fuel tank that was leaking pressure overnight, so the fuel pump had to build up the pressure for the engine to start.

Dealer found it by putting a pressure gauge on the car and left it overnight. Pressure in the morning was down to zero.

I think that they found out the specific source of the leak by a "smoke test" as I recall.

Good luck.

JackTripper

I experience the same thing.

dans15z06

Have you noticed a minor rough idle when cold? You would not notice it driving only when sitting still at idle.

BobSWFL

Possibly the engine is designed to generate a minimum level of oil pressure while spinning on the starter before the engine is allowed to fire up.

6Speeder

It's normal. These direct injection engines operate at VERY high fuel pressure, over 2,000 PSI. The pump in the tank only gets it to about 60 PSI, a mechanical pump run off the camshaft pressurizes it from there. This takes a little time.

b4i4getit

The OP also noted that his friend has the same car and it starts up immediately. So either his friends car is the oddball or a number of cars have an issue. It would be interesting to note how this shakes out.

tpapablo

Good to know. I also noticed that the Z's engine took a few more turns to start than in my C6. Didn't perceive it as a problem, but was curious about it.

hootowlc7

Normal

firstgear

When I start my '37 Ford that has a 396 with blower, I always turn the key on first and let the fuel pump fill up the lines and pressurized before I hit the key the rest of the way to engage starter......makes sense....

fpfaeth

Same exact thing.

Thomasmoto

Yes, it is perfectly fine. Our direct injection requires a very high fuel pressure and it takes a few seconds to build up to that and the slight miss is from the relatively cold range spark plugs that are required for the boost. It takes the plugs a moment as well because of the high pressure they have to survive under.

HolyRoller

Have you heard his Z start in the morning? Could be his definition of "immediately" is different from yours.

Hit the blue button and ask OnStar to give you any codes. They're very helpful. Hope nothing is in fact wrong with your Z and that you're having a great time with it otherwise.

nytrorcr

Mine takes longer than the C6 I just traded, but not so long a crank up that I am concerned.
I believe mine is normal but I can't say I've counted, but it is longer....