Why does crank time vary?
Fleet Mechanic
Joined: Jan 2007
Posts: 1,741
Likes: 3
I'll throw in my hat to the electrical system camp. (Do the cheap/easy stuff first.)
If your batteries are old (more than 3 years), CHANGE THEM. They won't hold 10 volts on cranking, and the both the PCM and FICM need 10 volts to do their thing. Don't use the "eyes" in the batteries to gauge their health. The FICM, especially, won't tolerate much low-voltage foolishness, and 2 batteries are MUCH cheaper than a FICM.
Also a word about the sensors themselves. The engine essentially "forgets" where it is in the firing sequence when you shut it down. It has to know where #1 is before it will inititate firing, via the Crank Position Sensor. So if the engine stops just after the #1 injection event, it will take two full rotations of the crank to "find" #1 again. This will make it take just a little longer to start.
-blaine
If your batteries are old (more than 3 years), CHANGE THEM. They won't hold 10 volts on cranking, and the both the PCM and FICM need 10 volts to do their thing. Don't use the "eyes" in the batteries to gauge their health. The FICM, especially, won't tolerate much low-voltage foolishness, and 2 batteries are MUCH cheaper than a FICM.
Also a word about the sensors themselves. The engine essentially "forgets" where it is in the firing sequence when you shut it down. It has to know where #1 is before it will inititate firing, via the Crank Position Sensor. So if the engine stops just after the #1 injection event, it will take two full rotations of the crank to "find" #1 again. This will make it take just a little longer to start.
-blaine
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Senior User
Joined: Aug 2004
Posts: 152
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This forum never ceases to amaze me with the information that is revealed here. All of this is very helpful and informative. My batteries are new and ficm was just rebuilt with premium service from Ed. I had the atlas 40 tune added as well. I run rotella t6 and it has 3k on it. Truck cranked normally yesterday. Have not been it today. With all I am learning, at this point I will not stress over it but remain vigilant.
Junior User
Joined: May 2011
Posts: 71
Likes: 1
From: Molalla
The air test is relatively easy to do once you get the parts. Harbor freight has an oil pressure test kit for 20 bucks that has the special M12x1.75 adapter you need. It comes out with a 1/8" npt fitting that you can get parts for at the hardware store to make an air plug with a valve. Or you can get the stuff Benny described. There are also lots of places on the site showing you how to do it. I pulled my ICP sensor off the right valve cover. Plugged in the air and turned it on. Used a garden hose as a stethoscope to hear air leaking. And used my auto enginuity software to operate the IPR. You really need to operate the IPR to isolate the leak. Mine was the o ring or d ring, whatever it is, on the passenger side. I changed the driver side at the same time. Just be careful putting it back together. I apparently wasn't careful enough and am still working on it. The air leak is now in one of the injector o rings under the passenger side oil rail, just as Benny described earlier in this thread.
Elder User
Joined: May 2008
Posts: 765
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From: Patricia, Alberta
I'm fighting the same thing as we speak. Did standpipes and dummy plugs with an e-bay kit, they lasted 5000 miles and washed out. Got new standpipes from Ford and it ran for 4 months, and 3 days ago it wouldn't start hot. Now it's the injector o-rings on the cheap useless Bostech injectors. Ford doesn't sell the o-rings...well, they do, but you have to buy a 400 dollar injector with them, so I'm taking a road trip to a diesel shop 80 miles away tomorrow to get o-rings.
Op, what about the glow plugs? If 1 or 2 or all of them died, it would make a hard start.
Op, what about the glow plugs? If 1 or 2 or all of them died, it would make a hard start.
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Senior User
Joined: Aug 2004
Posts: 152
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Currently all is well but the sudden delayed cold start last week is what inspired the post. I even called the ford tech that does my work and he said about what cheezit said and to pay attention to the hot starts. He told me if they start getting longer to give him a call.
Elder User
Joined: May 2008
Posts: 765
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From: Patricia, Alberta
If you're changing your hpo injector o-rings, here's a little bit of interesting info I discovered yesterday...the "top" of the o-ring groove isn't part of the injector housing, and can (and WILL) slide down while you're trying to install the o-ring! Couldn't figure out why 2 injectors looked normal, and the other 2 had no top to hold the o-ring in? It was under them. If you didn't notice it, the o-rings wouldn't last 3 seconds before they came blowing out.
My crank times are back to normal, I've found I have to get the oil hot, and go for a full throttle 90mph blast to get everything sealed up whenever I have the hpo system apart.
My crank times are back to normal, I've found I have to get the oil hot, and go for a full throttle 90mph blast to get everything sealed up whenever I have the hpo system apart.
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