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Discussion Starter #1 (Edited)
Lately, my truck has stalled, stumbled, hesitated from a stop....
A couple times back down or coming up a steep incline it has completely died.
A local diesel mechanic told me i should add a couple extra quarts of oil to it, that "possibly" it sounded like a bad or going bad pick up tube from the oil pump in the pan and that was a good way to test that theory.... he said that is a known issue with high mileage 7.3's

But my question is - any value in looking into replacing the cam position sensor?
those are cheap parts and sometimes the symptoms (CPS - stalling, hesitating, etc) are related.
Anything else I should be looking at?

It has never not started easily, starts right up, and it has not only stumbled on an incline, it has done it a few times now (in the past 3-5 days) while on flat ground.

Any advice, suggestions, or feedback would be appreciated here. details on truck are in the signature
Thanks. Mark
 

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Have you checked your oil level?
When was your last oil change?
What type of oil and viscosity?

The symptoms you describe have been reported when a CPS is failing and they are fairly easy to replace with a 10-mm wrench and a skinny arm.

Besides its a good idea to have a spare in the glove box so if that does not fix the issue then keep the old as a spare.

The philosophy of the forum is to not throw money into parts hoping one might eventually fix it but a CPS is cheap and matches the symptoms.

Just be sure to stick with Motorcraft brand (or IH if in farm country). Maybe $40.

You can also try removing the pigtail plastic connector on the ICP and drive with it off. It does not harm the engine at all and is a cheap method of troubleshooting the ICP. When disconnected, a default value is used so the improvement would be almost immediate.

While the pigtail is disconnected, look for an oil sheen inside the connector. It should not have any oil film but a failing ICP often allows a small amount of oil to leak past it.
 

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Have you checked the tin nut on the IPR, maybe the solenoid is sliding back on a hillside causing a stall.
 

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Second Arctic and jleedog's suggestions. Any CEL are you able to read codes? Please excuse the silly question as I don't mean to cause offense, but how much fuel do you have in the tank? I ran into a similar issue with our Ex and found a broken pick-up tube in the tank. At around 1/4 full the damn thing would die on moderate grades. I've also read others on this forum with similar symptoms who found clogged fuel pick-up tubes. Best of luck and let us know what you find...
 

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Discussion Starter #5
Thanks for the replies, I have changed the CPS and no luck, it still does it, very sporadically, but always when its hot, and always from a dead stop or if I put it in reverse or back down a driveway, etc....
Oil level is good, i use T6...
No CEL, no codes...
I have not looked at the IPR, i guess that will be my next step...
I am also hearing I should consider the torque converter going bad? and even look in the transmission pan and see if the filter is loose, or came off completely.
I did just have a transmission service done awhile back and the problem started after that. Ford did the service, they also told me they don't drop the pan or mess with the filter on a tranny service.
Any thoughts after the additional info?? Thanks
 

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I'd start by checking the transmission fluid level. Warm the engine to full operating temperature. Then park the truck on a level surface. Then pull out the transmission dipstick. There are two levels there on the dipstick, one for cold and one for hot. The transmission fluid should be in the hot range since you have warmed it up to full operating temperature. Add transmission fluid through the dipstick tube using a funnel if the fluid is low. The stalling, hesitating, and stumbling from a stop may be caused by the transmission not slipping correctly because the fluid level is not correct.
 

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Discussion Starter #7
I'd start by checking the transmission fluid level. Warm the engine to full operating temperature. Then park the truck on a level surface. Then pull out the transmission dipstick. There are two levels there on the dipstick, one for cold and one for hot. The transmission fluid should be in the hot range since you have warmed it up to full operating temperature. Add transmission fluid through the dipstick tube using a funnel if the fluid is low. The stalling, hesitating, and stumbling from a stop may be caused by the transmission not slipping correctly because the fluid level is not correct.
Thanks! i am going to check this first thing this morning...
 

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Discussion Starter #8
you check transmission fluid level while the engine running right? Its warm and running and in the hot range, so i guess its not the fluid level...
Unless, I should be checking it with the engine off? thx
 

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The next few things that I would check are:
1. Engine oil level.
The engine oil runs the injectors. If the engine oil level is too low, it could be possible that it is getting to the point where the the injectors are not getting enough oil to run properly.

2. When did you last change the engine oil?
If the oil is overdue for a change, the dirty, worn out oil may not be as good at running the injectors. There are thousands of different opinions on what oil is best to use. Personally, I use the Rotella T6 5w-40 in the winter, and Rotella T6 15w-40 in the summer. Both oils have the same viscosity once the engine is warmed up. The 5w-40 is thinner and easier to start when it is very cold. The 15w-40 is more viscous when cold; so I use it in the summer when I don't need the thinner oil for easier starting.

3. When did you last change the transmission fluid?
If transmission fluid is overdue for a change, and it is too dirty and worn out, it may cause the transmission to not slip the way it should. The transmission is programmed to slip until the engine rpms increase to the point where the engine has more torque. The engine has less torque at too low of rpm; so may be hesitating or even stalling because the transmission did not slip correctly to allow the engine to rev to the point where it had sufficient torque.
 

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you check transmission fluid level while the engine running right? Its warm and running and in the hot range, so i guess its not the fluid level...
Unless, I should be checking it with the engine off? thx
You did it right.

From the mouth of Super Moderator Mark Kovalsky,

"The cold level is meaningless. Don't ever use the cold reading for anything. The ONLY way to check the fluid is with the trans warmed up and idling in park. Anything else will give you the wrong level."

Mark
Former
FoMoCo Auto Trans Engineer 1988-2007

Fluid level in my Torqshift has me stumped
 

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Discussion Starter #11
The next few things that I would check are:
1. Engine oil level.
The engine oil runs the injectors. If the engine oil level is too low, it could be possible that it is getting to the point where the the injectors are not getting enough oil to run properly.

2. When did you last change the engine oil?
If the oil is overdue for a change, the dirty, worn out oil may not be as good at running the injectors. There are thousands of different opinions on what oil is best to use. Personally, I use the Rotella T6 5w-40 in the winter, and Rotella T6 15w-40 in the summer. Both oils have the same viscosity once the engine is warmed up. The 5w-40 is thinner and easier to start when it is very cold. The 15w-40 is more viscous when cold; so I use it in the summer when I don't need the thinner oil for easier starting.

3. When did you last change the transmission fluid?
If transmission fluid is overdue for a change, and it is too dirty and worn out, it may cause the transmission to not slip the way it should. The transmission is programmed to slip until the engine rpms increase to the point where the engine has more torque. The engine has less torque at too low of rpm; so may be hesitating or even stalling because the transmission did not slip correctly to allow the engine to rev to the point where it had sufficient torque.
Thanks for the reply...
I check engine oil often, is right on the mark, I use Rotella T6 15w-40.
I change it every 5K miles as well.
At one point in the diagnosis, a diesel mechanic told me to put a couple extra quarts in it and see if it stops. His thinking was maybe there was a hole or issue in the pickup tube of the oil pump and if it stopped with extra oil in it, that was an indicator.... it did not stop so as soon as it did it a couple more times I drained the extra oil back out and run it at its recommended level.

the transmission was serviced by ford a couple months ago and the problem started shortly after that. fluid level is in proper range and very clean. Ford did not drop the pan and change the filter though at the time of that service which surprises me. He said they suck it out and refill it now as the standard procedure, I cant hardly believe that.... thats why i am leaning toward wondering if the filter is loose, clogged or straight up disconnected in the pan... maybe that would be causing this? The more I read about high mileage transmissions, it seems changing the fluid can actually be a death sentence for the tranny... but overall it shifts good, no slips, and temps are always on the side...

I'm running out of options to consider (looking into the IPR and possibly an issue with the injector wires that go through the valve cover gaskets next?) it is very sporadic, does it when its up to operating temp, and does it on flat ground or when I back down a steep a driveway. the most concerning is when it stumbles and dies pulling out into traffic.
I have an HPOP gauge, and it seems to get good pressure through various rpm ranges.

No REALLY good diesel mechanics in my area that know the 7.3 intimately.... I'm in St. Louis. I met a guy that is suggesting I take the truck to a place called United Diesel Repair in Flowery Branch GA.... that could be a very long haul and expensive venture but am not ruling it out if I cant figure this out locally...
 
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