Just to expand on Chris' post a litttle..........

With a software tool like AE (auto Enginuity http://www.autoenginuity.com/) you can monitor just about every engine system on the 7.3L. For example here is a graphy of the injector control pressure Chris explained above. You can see the HPOP pressure can range from 500 to 3000 depending on the requested demand/engine load. This software comes in very handy when trying to diagnose HPOP health (especialy after adding power modifications since it is ussally the HPOP that will send a SES light during higher HP settings) and diagnose engine codes.

 

My wife can't figure out why I spend so much time reading random posts. She calls this site "Truckbook." There seem to be plankowners on this site, each with a particular knowledge area, that are WAY better than any Ford at fixing problems. And they do it all without even seeing the truck! Amazing....

 

lol...the facebook of trucks!!! never thought of it that way

you are right...there are a lot of great people here. finding this site kinda restored my faith in humanity.

 

Ok, so seeing if we can finish the oil cycle....LPOP scavenges from the pan and pulls it up to lube the motor and into the HPOP reservoir which forces oil to the injectors which also have fuel going to them via fuel lines. The air from the turbo is introduced to the cylinder in a separate chamber. When the injector fires, it is from the HPOP oil pressure (varies w/engine RPM) and fuel goes into the cylinder that also has hot air and then combustion takes place.

After the oil leaves the injector, it flows down the heads (under the valve covers, which is why you can take the covers off to see if injectors are firing, the oil will squirt but not crazy if you don't rev the motor) and back into the pan.

So, the oil is supplied in parallel to left and right but then serial to the cylinders? It seems the HPOP supplies left and right side simultaneously and then in turn from front to back (1-3-5-7 on passenger and 2-4-6-8 on driver sides, respective). That is why there are so many issues with the #8 injector? Why not the #7, too, if they are supplied in series?

Which makes me ask about the oil crossover concept. So, the heads don't get HPOP oil of equal pressure? In theory they should, but I guess if there are obstructions or failing injectors pressure can diminish over the length of the run to #7 and #8. So, the HPx mod seeks to equalize the oil pressure over the injectors. Can it really do this if the HPOP pushing the oil thru lines to the injectors? Can the crossover supply the required oil to the injectors (under such high pressure)? Or am I missing something here.

Another side purpose here is to learn which mods are good for engine longevity, high performance, reliability, etc. Seems some are specific for pushing lots of power while others are applicable to just making the motor last longer/experience less maintenance issues (kinda like preventative maintenance).

 

Here is everything about a turbocharger. LINK

 

The HPX crossoverline is about "balancing out the High Pressure Oil system with fewer pressure spikes (see Injection Control Pressure graphs below)". This and the graphs are copied from Sinister Diesel (ITP's) web site. Some have noticed a slightly quieter or smoother idle. I didn't, but still happy I installed it since I was getting ready to upgrade the injectors and wanted to have this, the fuel system in-tank and pre pump mods, and the regulated return done for longevity.

,

The left graph is ICP at idle -stock, the right graph is ICP at idle with the HPX crossover


To help answere the longevity mods question. Here are a few.

1. The in-tank fuel and pre-pump mod. This mod helps eliminate air entering the fuel system once the tank gets below 1/4. The stock mixing chamber design can lead to air being sucked into the fuel system below 1/4 tank. Getting the air out of the system is good for the injectors and has the side benefit of quieting down the diesel cackle some. Plus the added pre-pump fuel filter/water seperator will add another level of filtration.

2. Regulated return or fuel crossover kits

longevity benefits of this are increased fuel flow through the heads, eliminating starvation of the #8 cylinder. Any air bubbles in the fuel system can pass through the heads and out the regulators return port to the tank instead of through the fuel injectors (increased injector life and less injector noise). I did this mod to kind of "protect my investment" in the new injectors.

3. Used Oil Analysis - not really a "mod", but a tool to get a good snapshot of the internal wear, overall engine condition, and effectiveness of the air intake system. For $15 it is worth it IMO.

4. If/when you add a chip/tuner you will increase your EGT's. So then the focus tends to result in mods that will lower those higher EGT's. Here are some that will do this:

a more free flowing exhaust (4", 5")
air intake system
EBPV removal
AIH removal
intercooler upgrade

Hopefully I answere some of you points and didn't get off track to much

They key is to have an end result or final goal for the truck. What will be the primary focus? A power machine? Towing? Strictly longevity? Maybee a bit of each. But with a goal in mind it is then easier to plan a course of action.

 

Well I'll agree that you've got a better shot of getting things fixed without wasting too much money here, but the site was commissioned back in 1999 by Ken Payne. There's not too many left over from those days left around here. I didn't even really know what the internet was back then in terms of usefulness.

You catch on quick. You're just a few missing pieces away form completing the puzzle. Then answer to why trouble on #8 and not #7 is firing order. #6 fires immediately before #8, so oil in the rail has just been used to fire 6 and 8 gets a little starved. #7 is fine because 5 doesn't fire close to it.

 

Great reading... I just learned why my truck hisses after it's idled for awhile after start up.

"jeronlines", does that make you feel like less of an idiot asking questions?

I too want to learn basic stuff regarding the PSD. Pass the popcorn and keep it coming...

 

To get the same effect of balancing the HPO in each cylinder head that is achieved by installing an HPX you can remove the check valves
from each HPO outlet on the HPOP. This has been recommended by more then one HPOP modifier.

The check valve in each outlet is just a spring and disc.

 

This is some good turbo info specific to our PSDs.

 

So, I've been thinking and reading a lot and I think the oil system is pretty well covered. The only mod to it is really a form of increasing flow to the #8. This is accomplished via a crossover line or removing the HPOP check valves. In either case, pressure is equalized across the rails/galleys and the result is smoother delivery and firing.

On to the fuel system? I need to read more about it before I can even post an intelligent description.

 

Great stuff, and other than trying to figure out why my engine sounds really rough, this is the underlying reason for my questioning. I intend this truck to be my DD, vacation hauler and sometimes tow vehicle. I want to invest wisely, not randomly, and build a 1,000,000 mile truck. Ok, I'll settle for 750k

 

Hi all,
New to this forum. I enjoyed reading the info posted here regarding the over view of how it all works. Can anyone confirm this? The IDM is controlled by the PCM based on input from Cam Position Sensor, correct? Hence the reason a 7.3L will shut down when the CPM fails?

Been forced to learn this info the hard way (spent too much money chasing an injector stiction problem!) so this thread is a great deal of valuable knowledge! Thanks for posting it!

Mudtug2

 

The PCM takes signals (inputs) from the various sensors. It sends signals (outputs) to the IDM. So yes if the CPS fails the PCM cannot determine RPM, so the engine will shut down or not start.

 

The CPS is used to read the timing of the engine so the PCM and IDM know when to fire the injectors. If the CPS goes out the engine shuts down instead of risking injecting fuel at the wrong time and possibly blowing apart the motor.