Direct Injection and Slow Starting

Blazin383 · 04-26-2016, 08:32 AM

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?

Glen e · 04-26-2016, 08:38 AM

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

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

ParisTNDude · 04-26-2016, 08:41 AM

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?????

jdasnt3 · 04-26-2016, 08:42 AM

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

Iroc_Z28 · 04-26-2016, 08:44 AM

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:

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).

*Mr. Wyndham* · 04-26-2016, 08:46 AM

Quote:

Originally Posted by Iroc_Z28

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:

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).

andrec10 · 04-26-2016, 09:22 AM

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

HCGxKaLiBeR · 04-26-2016, 09:40 AM

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.

JonGSA · 04-26-2016, 09:45 AM

^ 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.

*Mr. Wyndham* · 04-26-2016, 09:59 AM

Quote:

Originally Posted by HCGxKaLiBeR

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.

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.

enzia35 · 04-26-2016, 10:10 AM

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.

L&M CAMARO 6 · 04-26-2016, 10:19 AM

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

MMC · 04-26-2016, 10:30 AM

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

vtirocz · 04-26-2016, 10:41 AM

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?

04-26-2016, 08:32 AM	#1
Blazin383 Drives: 2016 SS Join Date: Mar 2016 Location: Richland WA Posts: 451	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?

04-26-2016, 08:38 AM	#2
Glen e Retired from Car mfrs.... Drives: 2LT RS/HR-V Join Date: May 2013 Location: /Fort Lauderdale Posts: 10,048	#6 on my list- and I tell you why..... http://www.camaro6.com/forums/showth...=things+normal __________________ Glen CLICK HERE for detailing a new car: detailing for non detailers CLICK HERE for how to rinseless CLICK HERE for EASY wheel sealant

04-26-2016, 08:41 AM	#3
ParisTNDude Owning SSes for 50 Years Drives: Sharkskin Grey LT1 Join Date: Apr 2010 Location: Paris, TN Posts: 3,139 View My Garage	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????? __________________ The new ride: 2023 Camaro, LT1, Sharkskin Grey Previous Performance Cars: 1966 Chevelle SS 4M, 2010 Corvette 6M 1968 Dodge Charger R/T Auto 2012 1SS 6M 1982 Corvette Auto 2010 1SS 6A 1984 Corvette Auto 2016 2SS 8A 1999 Camaro Auto 2017 HBM 1SS 1le 2002 C5 Corvette 6M 2018 2SS 2006 Corvette Auto 2023 Camaro LT1

04-26-2016, 08:42 AM	#4
jdasnt3 Drives: 18 Silverado 1500 Join Date: Dec 2015 Location: Bradenton, FL Posts: 1,721	Not happening with ours, but we do live in a warm climate. __________________ 16 Red Hot 2SS A8: NPP, CAI Cold air, Ported TB, Fasterproms Ported intake, E85 flex, Formatto tuned. 11.80@118 with 1.92 60' (600-700 DA) on stock run flats.

04-26-2016, 08:44 AM	#5
Iroc_Z28 Drives: 2017 1SS 1LE Join Date: Sep 2014 Location: Canada Posts: 408	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: 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). __________________

04-26-2016, 09:22 AM	#7
andrec10 Drives: 2016 Camaro 2SS 6SP/Suby Legacy 6 Join Date: Oct 2015 Location: Hyde Park, NY Posts: 844	Makes sense now. 2000 PSI is nothing to sneeze at! __________________ TFPK40 Its Here! Finally came home on 3-31-16! Red Hot 2SS,6 Speed, NPP, MRC, Adrenaline Red interior, Silver Rally Stripes, NAV, Sunroof, 56W Split Spoke Wheels, Body color Hood vents, Body color Splash Guards and winter protection package. Ordered 1-28-16: 1100 2-11-2016 :2000 2-15-2016: 3000 TPW of 3/7...That went quick! 2-26-2016: 3400 Status TPW 3/7 3-5-2016 : 3800 3-8-2016 : 4300 3-11-2016 : 4B00 3-15-2016 : 4200 3-22-2016 : 4800 3-29-2016 : 6000!

04-26-2016, 09:40 AM	#8
HCGxKaLiBeR Drives: 2018 Audi S4/2016 Carmaro 2SS Join Date: Apr 2016 Location: CT Posts: 127	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.

04-26-2016, 09:45 AM	#9
JonGSA Drives: 2016 2SS Hyper Blue Join Date: Apr 2016 Location: CT Posts: 174	^ 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. __________________ '16 2SS Hyper Blue Metallic - M6 - NPP - MRC -Black bowties - CAI Intake - SW Cat Back w/NPP Other money pits: '13 S1000RR '11 R1200 GS Adventure '01 HD Sporty 1250

04-26-2016, 10:10 AM	#11
enzia35 Drives: '16 Garnet Red 1SS Join Date: Mar 2014 Location: College Station, TX Posts: 3,450	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. __________________ '16 Camaro 1SS '18 Miata GT Gone: '01 Camaro, '14 Camaro, '90 Miata

04-26-2016, 10:19 AM	#12
L&M CAMARO 6 Drives: Just a fan for now Join Date: Apr 2014 Location: ROCKPILE, Illinois Posts: 361	Never had that problem with my DI engines. Must be a gm thing.

04-26-2016, 10:30 AM	#13
MMC Drives: CGM 2SS/RS, 1987 & 2014 Silverado Join Date: Oct 2010 Location: Spencerport, NY Posts: 1,012	The colder the temperature the slower the crank the longer time it takes to develop the required pressure. __________________

04-26-2016, 10:41 AM	#14
vtirocz Drives: 2017 Camaro 1SS M6 Join Date: Apr 2015 Location: Indy Posts: 2,460	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?

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