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IPR duty cycle numbers and workings

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IPR duty cycle numbers and workings

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  #16  
Old 02-13-2018, 07:22 AM
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The 440 hz is nothing more than following the rules of the coil. The diameter, number of windings (in effect, the wire length), and wire gauge all play a part in "tuning" the coil to respond to specific electrical signals. Our IPR responds efficiently to pulse width modulated 440 hz.


In order for the IPR to work properly, it must allow the system time to mechanically react to the commands. It's not like oil pressure bounces from 700 PSI to 2500 PSI to 700 PSI in a few milliseconds - so the IPR has to allow time for feedback from the ICP sensor. IPR then becomes a relatively slow-to-react signal by design.


With that in mind, stock tuning limits the max IPR to 65%. The engineers didn't pull that number out of an unpleasant orifice and say "Sure. Why not?" They found that going from WOT to idle under the right conditions can create what I personally call a "Stinky Spike"... as explained in this [LINK]. Because of the potential for this spike, the Ford code monkeys limited the IPR to 65%.

Now... comes an aftermarket tuning guy that looks at the program rather simply, he might assume "Whoa! They left 35% more power on the table. That's over 80 HP!" That simplistic view would lead them to assume that a longer pulse width and a max 100% IPR will give all the fuel needed to deliver HP gains in the triple digits. Not exactly. Remember the Windex thing? All we have at our disposal per injection event is the fuel in the tiny reservoir. All the IPR and FIPW in the world won't deliver more fuel once it's spent - it just kills the ICP. Low ICP actually reduces HP... and I don't mean by a little. The best we can hope for with stock injectors is maybe a 60 - 65 HP bump - if tuned properly and given the air to support it.

As for the line spaces, the forum isn't like Facebook where hitting "Enter" sends the text. "Enter" here is like an old typewriter "Carriage Return" or a modern "Next Line". You don't have to code a line feed in, just hit "Enter" - or the little arrow on your portable device keyboard.
 
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  #17  
Old 02-13-2018, 06:08 PM
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Thank you Tug......I'm on my way to the link right now to see what else I can learn! DDT

Just a test here...I have hit ENTER 2 times and when I post this there (should) ba a space just as I see it here in the text box.

Will see what happens

Seemed to work just fine this time, Go Figure ,,,,DDT
 

Last edited by dieseldogtom; 02-13-2018 at 06:11 PM. Reason: add text
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  #18  
Old 02-13-2018, 06:58 PM
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Well O.K. Thanks for the link Tug BUT You fellas are going WAYYYY over my head!
Studying graphs of FIPW & ICP (stinky spikes...). That sounds like race truck tuning stuff. I'm just chugging along in a STOCK Van and interested in knowing the (basic's).
But that doesn't mean I don't get anything out of reading all those posts in the link.
Crankshaft degrees per MS and when injection should start along with lag times for mechanical things on the injector and coil field build times... Yeah, that stuff is interesting (sometimes) , But it's no fun when you know you are in over your head.
Thanks again for the extra information. Where is my ICP sensor anyway? I want to find it before I am in a parking lot with a no starter. So I can do a quick disconnect to rule out the ICP gone bad. DDT
 
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Old 02-14-2018, 05:40 AM
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ICP on driver side head. See pic for component locations.
 
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  #20  
Old 02-14-2018, 05:55 AM
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Originally Posted by dieseldogtom View Post
Well O.K. Thanks for the link Tug BUT You fellas are going WAYYYY over my head!....
Yeah.. your question took you straight to the deep end of the fuel right away. That was at the tail end of a series of threads that slowly built up an understanding of the sensors in the truck - and of graphing. It's like hearing the punchline without the benefit of hearing the joke first - "I don't get it."

Here is a very easy-going [LINK] that if followed through the series - leads you to the punchline. If "seeing" the sensor outputs isn't your thing, that's cool - not everybody gets into it.





Originally Posted by dieseldogtom View Post
Where is my ICP sensor anyway?....
 
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  #21  
Old 02-14-2018, 04:32 PM
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Watched the whole (SERIES) last night. Very informative. It gets a person to start to have a much bigger picture of all the sensors and parts that are working TOGETHER during an injection cycle. Thanks for the photos of ICP Location. Guess I (might) have to pull a bunch of stuff out before I will be able to see it. It's a VAN sooooo..... DDT
 
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  #22  
Old 02-14-2018, 04:48 PM
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Originally Posted by dieseldogtom View Post
Watched the whole (SERIES) last night. Very informative. It gets a person to start to have a much bigger picture of all the sensors and parts that are working TOGETHER during an injection cycle. Thanks for the photos of ICP Location. Guess I (might) have to pull a bunch of stuff out before I will be able to see it. It's a VAN sooooo..... DDT
On the bright side...your up pipes will be a breeze.
 
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Old 02-21-2018, 09:08 PM
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I was going to post about this event below but it seems to fit here nicely in this thread. The thread has helped me understand the way my 7.3 injection works. Man that first post did hurt my eyes tho.

This little anecdote should make you chuckle know that you've already read this thread and its excellent punctuation.

So I was romping slightly - well, maybe a little more - on the throttle yesterday, still mindful to spare my tranny, and when I let off the loud pedal I thought my motor was throwing a rod. Clankety clankety clank! But that clank diminished if I accelerated again, moderately or harder. Idle was horribly clanky and rough.

What to my wandering eyes did appear but my trusty Edge Insight console. IPR duty cycle was down to 3%! And injection pressure was 3300psi at idle! WILD STUFF, MAN, I said to myself. That new HPOP was singing like Fergie.

But I didn't fully understand what had happened until we hooked up the SnapOn Zeus. The IPR had failed....wide [edit] shut. So, I had unlimited pressure firing the injectors, and the ICP was screaming at the PCM to narrow that pulse width down as much as it could, and the darn thing still ran.

Amazing. These motors can be extremely resilient (if the crank position sensor is working). But I'm lucky I didn't blow an HPO line.

Now with this thread it's all becoming even more clear.
 
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Old 02-21-2018, 09:50 PM
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Originally Posted by RenoHuskerDu View Post
The IPR had failed....wide open.
Completely SHUT.




So, I had unlimited pressure firing the injectors, and the ICP was screaming at the PCM to narrow that pulse width down as much as it could, and the darn thing still ran.
What do you think happens during a Key On Engine Running test?
 
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  #25  
Old 02-21-2018, 10:24 PM
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Originally Posted by cleatus12r View Post
Completely SHUT.
My bad. Because a spring does the closing in the IPR

What do I think happens during a Key On Engine Running test? First tell us what that is. No stinky spikes plz.
 
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  #26  
Old 02-22-2018, 06:18 AM
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KOER (Key On, Engine Running). This is a test you initiate with AE or another test app while the engine is idling in neutral. For a short bit of time during the test, the IPR will close more than normal and the ICP will shoot up to about 2200 PSI.

Given normal (warm) idle ICP is in the 500 PSI range and the FIPW adjusts for the freak ICP, the engine will sound "aggressive" during this stage of the test. If the pressure goes too high or you have big-nozzle injectors, FIPW alone can't compensate for the excessive fuel delivered by the high ICP - so the PCM will actually shut the injectors off sporadically - leading to a big lope.

Layman's terms: During the test, the PCM jacks up the ICP (which is the real fuel pressure in the injectors). The sensors in the truck are yelling "Whoa! Where did all this power come from? The pistons are rotating too fast for idle! Hey PCM - back something off!"

The PCM is in the middle of a test, so it can't do what it normally does - back off the pressure. So... looking in the grab bag of tools the PCM has to control fueling, it first tries "OK... I'll just open the injectors for a shorter amount of time, letting less fuel into the cylinder".

This usually gets it done, but sometimes it has to go to the next level. Folks like me with bigger nozzles are already at the minimum injector open time with normal ICP, so in my case, the PCM is muttering under its breath "Crap... I can't lower the pressure, and I'm out of room to lower the injector-on timing. Fine. I'll show them who's boss - I'll just shut them off completely at strategic times to keep the RPM where it belongs." That's the lope recipe.
 
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  #27  
Old 02-22-2018, 07:47 AM
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Yep, thank you, that's exactly what I had. Horrible lumpy loud idle with the PCM trying desperately to strangle RPM down despite 238cc 80% injectors.

And apparently there was fuel puddled on top of the pistons despite the PCM's efforts. On restart after repair the lumpy idle continued and slowly tapered off.
 
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