Direct Injection and Slow Starting
 

My 2SS seems to need three or four turns before it fires, whereas my 2012 Vette always fired on the first roll. I thought I heard somewhere it was because of the direct injection, but I did a search and couldn't find any discussion on this.

Is it typical? Is it because of the direct injection, and if so, what is it about direct injection that causes it?

#6 on my list- and I tell you why.....

http://www.camaro6.com/forums/showth...=things+normal

I couldn't answer why, but it appears that most if not all of us are experiencing the same thing. I don't think it's an issue or fault at all, just an idiosyncrasy of the engine in our Camaros. The first time I started it after sitting over night, it worried me, but now it's become the norm and it's ok. It seems as though the engine doesn't get an initial dose of fuel for just a second or two?????

Not happening with ours, but we do live in a warm climate.

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 (driven off the cam) must build up the required pressure before the first injection event occurs (DI runs required around 2000+ psi fuel pressure compared to 40-60 psi for port injection).

Following are typical DI engine crank times using gasoline:

http://www.stingrayforums.com/forum/...gine-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).

:word:

Makes sense now. 2000 PSI is nothing to sneeze at!

Interesting. My bimmer would start to prime the injectors/pumps after I unlocked the door.

I have not get my 2ss yet. I can't test it. But I think if you unlocked the door and let it sit for 5-10 seconds before you hit the Start Engine button. Maybe it will improve the crank time.

^ My A4 did the same thing. Same direct injection HPFP setup. Everytime I opened the drivers door, I could hear the fuel pump prime up. No matter how cold or warm it was, it always started in under a second with 2-3 cranks tops. But then again, it was a smaller 4 cylinder. Not a 6.2l beast that has larger rails and pump to prime up before ignition.

Priming is different than pressurizing, I imagine, though I'm not a direct-injection engineer.

This car has an electric fuel pump in the tank to pressurize the feed lines and probably prime the main pump. Then the main pump is driven off of the camshaft with a three-lobe cam which produces the high pressures for the system.

It definitely seems pretty cool. I watched the Aston Martin Vulcan start up video, and that thing primed for a longgg time. So I figure it's a race car type thing, haha.

Never had that problem with my DI engines. Must be a gm thing.

The colder the temperature the slower the crank the longer time it takes to develop the required pressure.

My 3.6L DI engine ('09 Outlook) does not crank long before starting, even in freezing temperatures. I wonder why the system on the LT1 takes so much longer for a seemingly similar setup. Is there a reason the LT1 would take longer to build pressure than the 3.6?