Excessive Cranking?
Thread Starter
Le Mans Master
Joined: Jun 2004
Posts: 7,155
Likes: 154
From: The Arid Sunny Desert
Excessive Cranking?
I notice that on certain occasions, mostly in the morning after sitting overnight the car takes a little while to fire up. We have 91 octane fuel out here and so far, I've used a bottle of Techron Fuel system cleaner in the last tank and for this tank I poured STP 100 Octane in with the fuel. I'm used to 93 octane back east. Not that I expect that those things make a difference, but do you think it's a fuel pump issue or maybe a crank sensor? It's not a ton of cranks but more than it should to fire up. Thanks in advance.
Thread Starter
Le Mans Master
Joined: Jun 2004
Posts: 7,155
Likes: 154
From: The Arid Sunny Desert
I would doubt that only because it's been serviced by the dealer throughout its life (according to Carfax), and recently I had to go to an independent mechanic because my parking brake got stuck in the locked position, and because this particular shop had no history with the car, in addition to flashing the e-brake boost module they gave me a report on the entire mechanical condition of the car and everything all was new or like new. Sorry for the run-on banter.
Drifting
Joined: Oct 2005
Posts: 1,352
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From: Terrell North Carolina
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.
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.
Melting Slicks
Joined: Oct 2022
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From: Phoenix, Arizona
2025 C7 of the Year Finalist- Unmodified
2024 C7 of the Year Finalist - Unmodified
I would doubt that only because it's been serviced by the dealer throughout its life (according to Carfax), and recently I had to go to an independent mechanic because my parking brake got stuck in the locked position, and because this particular shop had no history with the car, in addition to flashing the e-brake boost module they gave me a report on the entire mechanical condition of the car and everything all was new or like new. Sorry for the run-on banter.
Moderator, Tech Contributor
Joined: Sep 2013
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From: Cape Coral, Florida
Where did you get these numbers from ??...I have Factory Service Info and I know this is not in there...if the ECT sensor is working correctly even at 0 degrees the car should start right up.
Le Mans Master
Joined: Oct 2014
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From: Atlanta GA
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Le Mans Master
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From: Atlanta GA
Dave
Drifting
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From: Terrell North Carolina
Le Mans Master
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From: Atlanta GA
If the crank or cam position sensor fails the ECM will revert to a default setting which results in a long crank ..... but it only took a few starts before my ECM popped as CEL light and a crank position sensor code . The sensor is cheap but it's behind the starter so it can be a pain in the a$$ to install especially since I have headers . After install there is a reset procedure that you have to run . Once I did the reset car started instantly.... just as it always had
Dave
Dave
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From: Charlotte, NC (formerly Endicott, NY)
My 2015 Z06 cranks quickly at times and cranks longer at other times. Either way, when the engine fires, it snaps to life. GM bulletins have indicated long cranks will happen and my car has had intermittent long cranks since I purchased it on 11/30/2015 (almost 10 years). In other words it is normal.
Bill
Bill
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From: Orange County Ca
Advanced
Joined: May 2024
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From: Backroads, TN
Mine does the same after a long sit. I have DI BMWs and you can hear the low pressure pump prime as you open the car door. The Corvette does not do that - the low pressure pump switches on as soon as you switch the ignition on.
I verified this (7MT car) by holding the start button down without pressing in the clutch. That turns the system on and I can hear the low pressure pump do its thing. The car will fire right up with no long crank every time I do that procedure no matter how long it has been sitting. It will not long crank in any temperature if it has been running recently. That long crank is from the fuel system priming. BMW figured it out and pre-primes the system before you ever touch the start button.
I am sure you can test this with an AT car by not pushing the brake pedal while holding the start button down.
I verified this (7MT car) by holding the start button down without pressing in the clutch. That turns the system on and I can hear the low pressure pump do its thing. The car will fire right up with no long crank every time I do that procedure no matter how long it has been sitting. It will not long crank in any temperature if it has been running recently. That long crank is from the fuel system priming. BMW figured it out and pre-primes the system before you ever touch the start button.
I am sure you can test this with an AT car by not pushing the brake pedal while holding the start button down.
