Major 7.3 Headscratcher

Arisley · Sep 24, 2014

Tuning. Try a different chip.

Sent from my truck while eating, adjusting the radio and passing a Mustang sideways.

lincolnlocker · Sep 24, 2014

whs^^^ or put it back to stock tuning and see what it does...

live life full throttle

dsberman94 · Sep 24, 2014

He already did that when he changed the PCM. Said above PCM had stock tune when swapped.

lincolnlocker · Sep 24, 2014

dsberman94 said:
He already did that when he changed the PCM. Said above PCM had stock tune when swapped.

missed it..

live life full throttle

ghohouston · Sep 24, 2014

But was it another stock pcm swapped in, or did he write some "stock" tune onto said pcm? Sorry if i missed it

Powerstroke Man 6.4 · Sep 25, 2014

Marty said:
Yes it will smooth out, just like when you unplug the ICP and the IPR d/c goes up and "estimates" 725 psi.

If all else fails and it smooths out with the ICP sensor unplugged and it defaults to the 7xx and idle smooth could you possibly put a chip in or pcm flash and tell a tuner to bump up ICP to the point where it smooths out at idle ie 7xx to fix the problem?

TyCorr · Sep 25, 2014

Or burn the sumbitsh to the ground, "I thiiiink its idling pretty smooth now."

Marty · Sep 25, 2014

ghohouston said:
But was it another stock pcm swapped in, or did he write some "stock" tune onto said pcm? Sorry if i missed it

Another stock PCM.

Powerstroke Man 6.4 said:
If all else fails and it smooths out with the ICP sensor unplugged and it defaults to the 7xx and idle smooth could you possibly put a chip in or pcm flash and tell a tuner to bump up ICP to the point where it smooths out at idle ie 7xx to fix the problem?

Not really the direction I am going with this. Something is wrong, and apparently has caused the truck to shut off on the customer. It needs to be figured out.

Bustedknuckles · Sep 25, 2014

What's the EBP sensor showing?

boggerr · Sep 25, 2014

Easy fix, change cap and rotor.

Check oil pressure at the hpop resevoir.

Arisley · Sep 25, 2014

boggerr said:
Easy fix, change cap and rotor.

Check oil pressure at the hpop resevoir.

Colder spark plugs.

mandkole · Sep 25, 2014

Bustedknuckles said:
What's the EBP sensor showing?

^^^ we may not be on same page, but EBP was something that I was thinking about as well.. The power supply for the MAP, EBP, and ICP is all on the same line. Any shorts, chafing, etc? It does not explain the sudden dying.

Can the cam gear pickups for the CPS die?

Arisley · Sep 25, 2014

Marty, have you checked the little fittings between the fuel lines and the heads. They may be clogged enough to have bad flow at idle, but once off idle, they flow fine.

Just a WAG.

Bustedknuckles · Sep 25, 2014

Arisley said:
Marty, have you checked the little fittings between the fuel lines and the heads. They may be clogged enough to have bad flow at idle, but once off idle, they flow fine.

Just a WAG.

His icp is fluctuating, don't see how the fuel side would affect that. Someone earlier posted about checking LPO which is a great idea!

Arisley · Sep 25, 2014

Forgot about that.

TurboM700 · Sep 25, 2014

Scope the CPS sensor and see if it follows the rpm drop. I have seen once where a trucks cam shaft would walk causing a weird idle issue.

Also are you taking reading thru the computer or with anctually scope. I have seen reading thru PCM be off before.

I usally use my 4 channel modis for this so I can monitor a few channels at once.

Mike

TyCorr · Sep 25, 2014

I thought all these trucks idled like chit?!

lincolnlocker · Sep 25, 2014

TurboM700 said:
Scope the CPS sensor and see if it follows the rpm drop. I have seen once where a trucks cam shaft would walk causing a weird idle issue.

Mike

must have read my threads on the issue. lol

live life full throttle

Marty · Sep 26, 2014

Ebps reading 17 @ idle. Absolute reading. Does this with tune and without tune.

Lpo is fine, so is icp off idle or with sensor unplugged.

I inspected icp sensor face and checked resistance, no marking and was the same from one 7.3 to another. This is a stock 7.3 and the cam gear hasn't been off. I doubt it has cam gear walk for that reason too.