I am still trying to get a good understanding of all things IPR, ICP. Any help/comments /info appreciated.
I'm working with a 2003 E-350 7.3L . (NO Problems. Just wanting to learn more). I think I got confused because the Duty Cycle #'s for the 6.0 & 7.3 are slightly different for their Max. values.

What I (think) I learned from Oregon Fuel Injection, Inc. Site is the 1999 to 2003 7.3L engines will see IPR DC #'s between 09% to 40%. They show IPR numbers like.... IDLE = 9 - 11% Hard Acceleration = 35 - 40% (They also show a WOT in Neutral of between 18 - 21%). Those numbers seem to be what I am seeing.

What I don't have a good understanding of is the term used (duty cycle) or why the numbers used or (programmed) into the PCM ... are between 09 and 40%. In my mind it should be between 0 to 100%.

So I'm hoping for an explanation about (duty cycle). Or maybe better asked....What exactly is this IPR valve and what seems to be an electric controlled coil around it doing? Is it just sliding a piston that opens or closes some internal port to control HPOP oil pressure to the Head Galleries? They don't just call it % open or closed.They use this term Duty Cycle.

Also, is the ICP sensor located on the front of the drivers side head? I have learned, that is something I will want to be able to easily locate to disconnect as part of diagnosing a no start condition. ( IIUC it causes the PCM to default to a 725 p.s.i. reading from the ICP sensor, thus allowing the engine to start if it should be that you have a bad ICP sensor).
So my basic question is about how and why the IPR works and the numbers and (term) used to describe it? Thanks for any input on the subject. DDT

 

Paragraphs, my friend, paragraphs.

 

The ICP voltage increases or decreases based on what the requirement for the engine load and what's desired. That is the whole function of the ICP. This is based on both Rotation Crank Value and Throttle Position.

The IPR regulates that pressure. The IPR is from 0-65%. 0 being closed and 65 being open all the way. The PCM sends the signal based on the ICP. The signal is Voltage sent to the Coil of the IPR, the more voltage the more open, the less voltage the less open. A Spring does the closing in the IPR.

So, the ICP is the Water Pressure, the IPR is the Nozzle on the Garden hose.

That's about the simplest way to explain it. It is, really, that simple.

ICP: 5 Volt Reference Circuit, 1.0 vdc @ 580 psig, and 3.22volts @ 2520 psig.

These are the table perimeters.

ICP Vdc
0 0.2
200 0.4
400 0.73
600 0.96
800 1.2
1000 1.4
1200 1.6
1400 1.9
1600 2.1
1800 2.3
2000 2.6
2200 2.8
2400 3.0
2600 3.3
2800 3.5
3000 3.8

This is the Duty Cycle - A Duty Cycle is a time per division of an electrical waveform, a "Signal" to or from the PCM. Also known as I/O on a Bus. In this instance, the cycle of operation of a the IPR operating intermittently rather than continuously.

IPR: Idle Warm: 8% - 14%, Idle Cold 10% - 15%, Electromagnetic Coil Test: OHMS = 10.2 - 10.6, Range: 0% - 65% (Not more than 20% Starting).

Now, my eyes hurt from reading your post. A carriage return occasionally would help.

 

Not quite.

The voltage is a constant 12 volts to the IPR. The valve is controlled by a variable duty cycle carried on a 440Hz frequency on the ground side through the PCM.

Also, the higher the duty cycle (higher average current through the IPR coil), the more CLOSED the IPR valve is thus keeping the return from allowing higher flow back to the oil reservoir.

 

You are right! (Good catch)

 

I apologize, I didn't read the whole thing. My old eyes kept getting lost in a sea of words, but I think I have the gist of the question (or at least I hope). You might want to click this [LINK]

 

Here's a question about the intensifier piston and injector...

If fuel pressure is 50 psi, and ICP is a given value (let's say 2000 psi for an example), it injects a certain volume of fuel at a certain pressure, right?

What happens if the fuel pressure is 100 psi and same 2000 psi for ICP?

Being DOUBLE the fuel pressure would seem to be significant, but only 50 psi is very small compared to the ICP oil pressures.

Liquid is not compressible, so there *shouldn't* be a volume difference per injection, right?

So the question: What effect, if any, does high fuel pressure have on the injection and running process?

(Other than premature Parker seal failures and maybe extra wear on the pump and bowl seals)

 

No effect at all. Think Windex spray bottle. Spraying doesn't directly use the fluid in the bottle, it uses what's in the tiny reservoir in the handle. Releasing the handle is the action that refills the tiny reservoir from the bottle.

The HEUI is very similar in this regard - the fuel pressure does nothing more than make sure the tiny reservoir in the injector is refilled before it is needed for the next injection event. Too high - premature wear and tear. Too low- reservoir fails to reload at high RPMs and/or fuel demand. 50 to 60 PSI - Goldilocks.

 

O.K. Thanks for the information.. I apologize for the lack of proper layout & format of the post.
Maybe some further information?
1st. And let me start by thanking you pirshwagon for the Table Voltages and IPR Coil Test OHMS numbers.

You say the IPR DC is from 0 to 65%. I get the 0% (as I imagine you must have a starting point when the engine and key is OFF. But the information I read on the Oregon Fuel Injection Site was for a 35 to 40% DC at Hard Acceleration. (I generally interpret hard acceleration. as WOT.
You listed the Max. IPR DC as 65%. So is that possibly the programed PCM limit? IE: If the HPOP or some other portion of the closed oil system is leaking or faulting, The PCM will (allow) the IPR DC to go to the Max. of 65% in an attempt to compensate for the leak/fault before it throws a DTC or otherwise somehow stops attempting to make a correction?

I ask because I have gone WOT/ Hard Acceleration, and I have only ever saw my IPR Duty Cycles in the high 30's.

2nd. To cleatus12r. Glad you made the technical correction/ catch about the electrical operation of the IPR.

If I understand what you wrote....The spring in the IPR is always holding the piston OPEN, and the coil when getting MORE Duty Cycle is what pulls or pushes the piston to close OFF the oil return circuit in the HPOP, thus creating the Higher oil pressure in the oil galleries, thus the ICP sensor reads those higher pressures and based on constantly changing TPS , RPM's, HP and I am sure other sensors that are signaling the PCM, There is a constantly changing Duty Cycle percentage being sent to the IPR ?

If I basically have this correct I still must admit a bit of curiosity of wanting to understand the 440Hz on the ground/return side. Does the 440Hz change? Or does that remain constant and some other signal (within) the 440 wave change? This sounds to me like understanding Radio wave carriers and signals? Am I close?

Anyway,,,,I thank all of you for the time to read my way to long posts and detailed questions. I am SURE there are others that want to understand this stuff and might figure it out by reading all my questions. Thanks again guys...... DDT

 

Google "pulse width modulation". In the case of the engine in question, the frequency of 440Hz remains constant.

 

That 35%-40% you're reading is what they claimed as "averages" for a bone stock truck.

Stock calibration limits to around that 65% duty cycle.

Keep in mind what Cletus posted, this is a duty cycle, not a voltage or percentage of valve closed. Meaning 40% duty cycle doesn't actually translate to the valve being 40% closed. 65% duty cycle doesn't mean the valve is 65% closed.

Now it is possible with tuning to change that maximum duty cycle in the calibration to go all the way to 100%. The problem is that in almost every single scenario, nothing is gained. You don't get any additional oil pressure when that threshold is raised. So 65% duty cycle will be the same oil pressure in the same exact scenario as it would be at 95% duty cycle.

Which brings us to the next part....

Just because you aren't reaching 40% duty cycle or 65% duty cycle doesn't mean that you are losing oil pressure. In fact, it's the opposite. It means you are maintaining the pressure that the calibration is asking for during the injection event. If the PCM is asking for 2500 PSI, and one truck did it at 30% DC, and another did it at 40%, it doesn't matter.

If the HPOP was unable to keep up with the demand and oil pressure was dropping, the PCM would command a higher duty cycle to bring up the pressure. If the pressure still doesn't come up, the PCM will continue to demand a higher duty cycle until it reaches the limit set in the calibration of the PCM (factory 65%). If at the max commanded duty cycle the oil pressure still hasn't reached what is demanded, a code will be set and the check engine light illuminated. So if yours hits 2500 PSI at 30%, but your buddy is sitting at 2100 PSI at 65% and tripping the engine light, he's got an issue and yours is perfectly fine.

Hopefully that explains it without getting too technical and confusing for everyone.

 

Dieseldogtom,

First let me say you are asking some very good questions

As the guys are saying, the IPR%, ICP, and other items are all pieces of a moving puzzle, usually "seeking a target" of some sort. As tuners, these fellows are very familiar with that process, which some of us consider an art form as to how they attempt to define and meet those target values.

I would invite you to check out some of the graphing threads.

Although not written in stone, there are sections of performance- such as 45-85mph WOT- during which certain relations between sensor values play out and can be visualized, often leading to quick and fairly accurate assessments of "healthy performance" or shortcomings.

A screen snapshot, max or min values, or whatnot can be helpful are are only one datapoint and of limited (although potentially important) value.

I hope I explained that well enough

As for the grammar? Heck, we don't care.

But the formatting and blank lines? VERY important. As a group we use this site on computers, tablets, phones, maybe even tin cans and string, LOL!

We tend to skim a bit. We go back and forth to the information and any other reference material we believe would be helpful to contribute to the thread.

As such, it is easy to lose one's place in a long, run together paragraph. But feel very free to offend your English teacher's version of paragraphs. Often online/conversational style posts do NOT follow her rules,

I often break each change in thought, for sure, but I also try to break up data sets, separating important info/specs, and sometimes just when my pinky finger feels neglected, LOL.

So feel free to post whatever questions and discussions you like, but give us a "break" (paragraph) once in a while so we don't get lost along the way

 

Thanks everyone. I have a MUCH better understanding now of what was probably my biggest confusion.
The term (Duty Cycle). And thanks for the links.
I'm pretty sure I now get that this is a situation that is related to computers and how they work vs. the old school way of controlling a coils voltage with increased or decreased voltage values . I also see that I probably don't really need to know anything about what frequency the IPR/PCM signal is operating on. Just that Duty Cycle is the ON vs. OFF time % and that it is happening hundreds of times a second to (I guess cause a varying degree of magnetic field to the IPR coil) which in turn pulls or pushes the IPR Piston further in or out.
get now that the duty cycle % is NOT a value of % open or closed of the actual valve or piston in the IPR. From what I have read it seems that the 490 Hz frequency seems to be a fairly commonly used freq. Is this just more to do with maybe long time computer industry standards?
Any further comments appreciated. This free education on the FTE site is a GREAT thing! Thanks again... DDT

 

P.S. I did indexing and spacing when I wrote the above post. Guess it only works if you go to GO Advanced button.

 

P.S. I did indexing and spacing when I wrote the above post. Guess it only works if you go to GO Advanced button.