Cranks for a while before starting
Thread Starter
Racer
Joined: Jul 2005
Posts: 303
Likes: 68
Cranks for a while before starting
I noticed that no matter how long after I turned the motor off (5 days or 5 minutes), it seems like it takes a solid five seconds for my motor to fire up from when it starts cranking. My battery is always charged, so it isn't a battery issue. Do others notice an unusually long cranking period?
Burning Brakes
Joined: Jun 2015
Posts: 928
Likes: 633
I noticed that no matter how long after I turned the motor off (5 days or 5 minutes), it seems like it takes a solid five seconds for my motor to fire up from when it starts cranking. My battery is always charged, so it isn't a battery issue. Do others notice an unusually long cranking period?
Instructor
Joined: Nov 2007
Posts: 208
Likes: 3
From: Cookeville Tn
Pro
Joined: Nov 2015
Posts: 564
Likes: 147
From: San Antonio Texas
I wondered that also and I think its all in the function of the push button start feature. My ZL-1 I always turned key a little and let the fuel pump pressurize then cranked it and it fired right up immediately. I'm sure if GM had programmed the start sequence to wait a couple of seconds before cranking to let fuel pressure rise it would eliminate the excessive cranking. But oh well so long as it fires I'm good with it.
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Instructor
Joined: Jan 2015
Posts: 138
Likes: 30
From: Ashburn VA
I wondered that also and I think its all in the function of the push button start feature. My ZL-1 I always turned key a little and let the fuel pump pressurize then cranked it and it fired right up immediately. I'm sure if GM had programmed the start sequence to wait a couple of seconds before cranking to let fuel pressure rise it would eliminate the excessive cranking. But oh well so long as it fires I'm good with it.
Safety Car
Joined: Aug 2012
Posts: 3,960
Likes: 1,106
This is normal for all GDI engines and it was the same thing many diesel pickup drivers wondered about when HPCR (high pressure common rail) injection was adopted for diesel engines several years before it was used for gasoline engines. The control system for the injectors is based upon having the required/expected fuel rail pressure for operation so the injectors aren't triggered until commanded fuel rail pressure is available and this takes several revolutions for the camshaft driven high pressure fuel pump to provide.
If you ever drive your Z06 in very cold weather you will notice slightly longer cranking time because with the thicker oil the cranking speed is slightly slower and it still takes the same number of revolutions for the fuel pump to pressurize the common rail system. The same will be noticed with a battery that isn't fully charged or is losing capacity.
If you ever drive your Z06 in very cold weather you will notice slightly longer cranking time because with the thicker oil the cranking speed is slightly slower and it still takes the same number of revolutions for the fuel pump to pressurize the common rail system. The same will be noticed with a battery that isn't fully charged or is losing capacity.
6th Gear
Joined: Sep 2015
Posts: 6
Likes: 0
I have notice that when I put my car in tour mode and left it over night and started it the next day and seemed a lot easier to crank. Then I put it in sport mode and it was harder to crank. Give it a try and see if it makes a difference.
Tech Contributor
Joined: Oct 1999
Posts: 41,066
Likes: 9,829
From: Charlotte, NC (formerly Endicott, NY)
OP: It all depends on how fast the starter is cranking the engine. If it is slow then you might have an electrical issue. However, if it spins the engine fast (mine spins the engine faster than any other car I have ever owned except for ones where I had the spark plugs pulled) then there is no issue with the starter.
Bill
Bill
Racer
Joined: Sep 2012
Posts: 342
Likes: 52
The DI does require building up fuel pressure, but:
"(...after 5 days or 5 minutes), it seems like it takes a solid five seconds..."
If the quote isn't an exaggeration, I'm not sure that's normal. If I've run the car, then parked it for a while (e.g. at a restaurant...hour or two), it fires right up. Also, mine never takes 5 full seconds to crank, even after sitting for a week...maybe 2 or 3.
FWIW.
"(...after 5 days or 5 minutes), it seems like it takes a solid five seconds..."
If the quote isn't an exaggeration, I'm not sure that's normal. If I've run the car, then parked it for a while (e.g. at a restaurant...hour or two), it fires right up. Also, mine never takes 5 full seconds to crank, even after sitting for a week...maybe 2 or 3.
FWIW.
Drifting
Joined: Jan 2006
Posts: 1,498
Likes: 166
From: Metro Detroit - miss FL
I look at it being similar to how I've started my cars that don't need a key. Roll the starter for a few seconds and then hit the ignition. The Corvette might get the engine turning over for a few moments before lighting the ignition.
Last edited by Jus Cruisin; Dec 5, 2015 at 01:16 PM.
Safety Car
Joined: Aug 2012
Posts: 3,960
Likes: 1,106
It should not take 5 seconds but unless you are accurately timing it you may be misjudging; few people can accurately judge short periods of time.
From GM the following are expected start times:
Above 50F may take up to 1.5 seconds
From 14F-49F up to 2.5 seconds
Unless the ambient temperature is -4F or colder it should not take 5 seconds.
If your engine is exceeding these times then either the cranking RPM is low, the high pressure fuel side of the system isn't building pressure properly, or the rail pressure sensor is returning a false low reading. IN any case if your time is outside of those specified it is time to see your dealer.
From GM the following are expected start times:
Above 50F may take up to 1.5 seconds
From 14F-49F up to 2.5 seconds
Unless the ambient temperature is -4F or colder it should not take 5 seconds.
If your engine is exceeding these times then either the cranking RPM is low, the high pressure fuel side of the system isn't building pressure properly, or the rail pressure sensor is returning a false low reading. IN any case if your time is outside of those specified it is time to see your dealer.
Thread Starter
Racer
Joined: Jul 2005
Posts: 303
Likes: 68
It should not take 5 seconds but unless you are accurately timing it you may be misjudging; few people can accurately judge short periods of time.
From GM the following are expected start times:
Above 50F may take up to 1.5 seconds
From 14F-49F up to 2.5 seconds
Unless the ambient temperature is -4F or colder it should not take 5 seconds.
If your engine is exceeding these times then either the cranking RPM is low, the high pressure fuel side of the system isn't building pressure properly, or the rail pressure sensor is returning a false low reading. IN any case if your time is outside of those specified it is time to see your dealer.
From GM the following are expected start times:
Above 50F may take up to 1.5 seconds
From 14F-49F up to 2.5 seconds
Unless the ambient temperature is -4F or colder it should not take 5 seconds.
If your engine is exceeding these times then either the cranking RPM is low, the high pressure fuel side of the system isn't building pressure properly, or the rail pressure sensor is returning a false low reading. IN any case if your time is outside of those specified it is time to see your dealer.
Instructor
Joined: Jan 2015
Posts: 138
Likes: 30
From: Ashburn VA
I was experiencing this same issue and we "think" it is the high pressure fuel pump not pressurizing the rails because it is dumping fuel into the oil. Since we are still two weeks into waiting on a pump, not really had a chance to diagnose. There is definitely fuel in the oil. I think my car is a freak issue, but I'd keep an eye on your oil level. Check per the owners manual. You need to warm the engine then wait 5-10 minutes.