Fuel Injectors Rating

[gmctd]

That is correct, Schiker, and I appreciate your helpful input - that is the fuel metering valve, of which one inherent function is spill

GMTDScan is a wunnerful pcware scantool, but that and a DVM does not tell the whole story - Closure Time pulse from the FSD module tells the PCM to start timing the metering pulse, which varies in width according to demand fuelrate - overall pw timing includes CT

LIMP MODE fixes idle rpm, locks TSM timing, limits max fuel rate by limiting the metering pulse width, locks out turbo management, locks out Cruise, limits the 4L80E to two lower ranges - this results when CPS or OS failure occurs, CT is too long or erratic\intermittent, etc - these limitations resut in long-start condition, requiring long cranking periods before engine will fire

Secondary "limp modes" occur when certain parameters are exceeded, such as high Boost, where PCM will set DTC, reducing and limiting fuel rate and limiting turbo control until restart - however, PCM is too primitive to reduce fuel rate when Boost is too low for demand conditions, thus the black smoke with reduced power when wg system fails - that scenario is not a limp mode

This is all digital, based on the 'clock' pulses from the OS on the 512-slot track on the encoder disk, and sync'ed by the clock pulses from the 8-slot cylinder track and the CPS - PCM has 64 counts per cylinder with which to work it's magic - the 64 counts are spread across TDC of each cylinder, some BTDC, some ATDC, allowing precise management of the injection\combustion event

Any perceived "voltage variation" is due to frequency and ELI - someone may have been texting a floozie when the instructor was covering that concept, eh...............

However, low battery voltage at the FSD, be it from grounding, resistive connection, or failing battery system, will increase CT due to slower FS reaction time, thus affecting injection event timing - DTC36: there's ole ELI, at it again................

And, Buddy, you'd get better response if you asked if things work like you think they do - query indicates seeking enlightenment vis a vis opinion - statement implies knowledge, fact - very confusing to anyone else trying to learn - and the statee tends to look like an idiot when correct function is explained - go back and read thru some of your posted statements in this thread to get a sense of that scenario - fe, paraphrasing, fuel is metered by varying the voltage......................

 

[Acesneights1]

OK now I'm confused because what my friend Tony is telling me makes sense. Here is the thread. What am I missing ?

Quote:
Originally Posted by acesneights1
Not clear on the priming. So if it runs out of fuel for whatever reason(like floating PS bottle) I should have been loosening the Injector lines? Cause I didn't do that which is maybe why I could not get it to run. All I did when it stalled and wouldn't start was pump the hand pump till it got resistance and then tried to start it. Was that my problem all along with why I could only get it to start by lots of ether or pulling it down the road because that will start to make more sense now.

Yep, hafta bleed em at the head, Close to the nozzle as possible. All nozzles (injectors) that have a return line on them, on any engine. .


Quote:
Originally Posted by acesneights1
Also something I am still fuzzy about with the injectors. The injectors in this engine are just nozzles like say on a powerwasher ? They don't "Pop" at the injector ? So then how dos that work ? At injection event does it pop at the IP ? I'm having trouble picturing how that would work because if the injector doesn't "Pop" wouldn't the fuel run out of it ? Just want to understand how it works . Makes it easier t work on.

Hafta use the correct terminology. An injection nozzle unloads (pops) at a given pressure. Take a 3406B. 23K lbs of peak pressure stock at the end of the line. Nozzles "pop" at 17500 psi. Injection nozzles, wether capsule, pensil, inner return, or "heavy head" 7000 series standard Cat, have a needle and seat that unload at a set pressure. They remain sealed (or supposed to) until line pressure reaches unloading pressure.

A pressure washer nozzle is just a sized orifice. Completely different.

Injectors, on the other hand, are either cam actuated, cam actuated solenoid controlled, Huei (oil pressure actuated), or strictly electronic, either plunger controlled, or Piezo wafer. You know how they all work, or just ask...
__________________

 

[gmctd]

I've ghost-written your post (prolly shoulda done it in a quote - sorry 'bout that - I am, as you may remember, legally dyslexic) - go back and reread it, see if that makes more sense, 'cause he's right - bleed these injectors "as close to the nozzle as possible" is the injector pipe fitting at the injector "head"

Proper method of bleeding is not, as some think, unscrewing the fitting, watching for fuel to squirt out - you're only looking at less than 10mm3 per stroke at cranking rpm, which is only a slight slight trickle if pipe is open-ended - so, tighten the fittings, then back one fitting off 1/8-1/4 turn, just enuff to allow less dense air to escape while containing the denser fuel - air will escape at much much lower than pop pressure - 'nuther words, when it stops bubbling and fuel is slightly oozing, it's bled - keep cranking while tightening the fitting - move to the next injector, repeating till engine cranks - then continue till all are bubble-free

If you totally uncap the pipe by unscrewing the fitting, the IP never gets to pop pressure, sucks air back into the pipe as pressure drops, so you will never get the pipe bled

A pressure washer is a fixed-rpm pump, pumping fixed volume at fixed pressure set by nozzle orifice diameter - unscrew\remove the nozzle, run the pump, see what happens to pressure = volume way increases, pressure way drops - pump will have a spring-loaded safety "pop-off" and regulator valve to limit upper range of pressure when wand valve is released, or should hose become crimped or nozzle stops up or...........

 

[buddy]

The signal from the PMD to the FS is not digital.

Change in frequency would not show a change in amplitude on a DVM, thats just nonsense. Voltage is determined by the peak to peak amplitude, has nothing to do with frequency. It could be 60Hz like commercial power 120V, or that same 120V could come out at 400Hz or whatever.

 

[Acesneights1]

OK but what that thread was about was Tony kept referring to the injectors as nozzles which was getting me confused. The GM 6.5 Manual also refers to what we tend to call injectors, nozzles . Tony was trying to explain to me that what I have a nozzles not "injectors". That is why I was getting confused. When Someone says nozzle I think like the end of a powerwasher and that would not make sense. The engine being discussed in that thread was a 3208T cat but same thing really applies to 6.5 ?? Or am I just more conused ??
The other issue was I could not get the truck to strat even after priming i but that was because I was not priming it properly. How we finally got that truck started was dragging it down the road in gear to spin the motor faster than the starter could because as I have said before I really really don't like ether even though in the case of a low compression 3208T it's almost a nessecity..

 

[bison]

I've ghost-written your post (prolly shoulda done it in a quote - sorry 'bout that - I am, as you may remember, legally dyslexic) - go back and reread it, see if that makes more sense, 'cause he's right - bleed these injectors "as close to the nozzle as possible" is the injector pipe fitting at the injector "head"

Proper method of bleeding is not, as some think, unscrewing the fitting, watching for fuel to squirt out - you're only looking at less than 10mm3 per stroke at cranking rpm, which is only a slight slight trickle if pipe is open-ended - so, tighten the fittings, then back one fitting off 1/8-1/4 turn, just enuff to allow less dense air to escape while containing the denser fuel - air will escape at much much lower than pop pressure - 'nuther words, when it stops bubbling and fuel is slightly oozing, it's bled - keep cranking while tightening the fitting - move to the next injector, repeating till engine cranks - then continue till all are bubble-free

If you totally uncap the pipe by unscrewing the fitting, the IP never gets to pop pressure, sucks air back into the pipe as pressure drops, so you will never get the pipe bled

A pressure washer is a fixed-rpm pump, pumping fixed volume at fixed pressure set by nozzle orifice diameter - unscrew\remove the nozzle, run the pump, see what happens to pressure = volume way increases, pressure way drops - pump will have a spring-loaded safety "pop-off" and regulator valve to limit upper range of pressure when wand valve is released, or should hose become crimped or nozzle stops up or...........

Never had no trouble bleeding Ip,lines and injectors on any diesel by cracking the inj line nut and cranking till fuel spilled out all of them,tighten the nuts,and run they did.Any remaining air will quikly be purged in a few sec of running.
The 2 strokes are more finnicky to bleed.

 

[bison]

IMO,the term "nozzle" is a loose term used in many diff aplications.It so happens that the diesel injector valve and seat are commonly called nozzles.
The assembly that holds the Nozzle,spring and other parts is commonly called the injector.
Even in the 2 stroke its called an injector altough in that case its the IP as well.

 

[buddy]

Edit, I think they mean all fuel injectors are just nozzles.

A detailed definition of injector include the pump, along with the valve and nozzle. So fuel "injectors" only have a valve and nozzle, and an external pump creates the fuel injection system.

Its an argument, but not one worth making. Symantics.

 

[gmctd]

Devil is in the detail - "cracking the nut" is not loosening it entirely, merely backing off by 1/8-1/4 turn - and you can do all 4-umpteen if they are easy access - this engine will fire and run on ~4th bleed - rest can be done with engine running, or let it run at fast idle till smooths out

Point being, "crack" each line, don't back the nut anywhere near full off

 

[gmctd]

Yep, folks - nozzles, injectors; lift pump, transfer pump; engine oil, motor oil; tomato, tomahto; semantics indeed

Oh, and shhhhh, quiet, everybody - let's not tell Buddy about pulse repitition rate and pulse-width modulation and effective voltage and digital waveform vs sinewave and RMS and......well, you know.......mum's the word, eh.....................

 

[gmctd]

One thing to remember when asking for info from older Diesel mechanics: very few liked the big DD 8.2 V8, primarily because the valve rocker arm clearances needed to be adjusted every 12000mi, iirc - hassle enuff in itself, the injector pipes, similar to the 6.2\6.5, had to be removed to pull the valve covers - those with a bad taste in their mouths from the 8.2 usually have nothing good to say about the 6.2\6.5, similar to my (patooie!) gasser routine

 

[buddy]

Oh yeah, gmctd's repetitive petty insulting is real intelligent too, wonderful attitude for a moderator.

You disguise your stupid statements with insults. Like shrugging off the fact that you told everyone that injection pressure doesnt go over pop pressure, and marine injectors will kill your IPs, and emphatically telling me I was stupid for implying pressure went over pop pressure. And you say but it does set the idle injection pressure, like we all didnt already get that and the point was that the pump will run at higher pressures no problem.

And you say the frequency impacts the voltage, completely wrong, and try to play it off by spewing other irrelevant terms.

The signal to the FS is not one that the FS analyzes and determines what to do. It is an analog power waveform that the PCM digitally synthesized. Is that incorrect? Does the FS have some digital processor inside of it that reads the peak as a 1 and the low as a 0 and determine that true means move the plunger out?

How is anyone supposed to have input here if the moderators insult anyone that says something that differs in their opinion.

 

[Matt Bachand]

Not sure why the bad blood flows, but it does.

Very great topics going on here, I'm learning a ton. In the last few weeks alone, I know completely understand TDCO and base timing and how it impacts my vehicle.

My understanding of my injection pump is growing rapidly. It is no longer an unknown to me, as well as timing and advancement benefits and whatnot. In fact, the way the PCM adjusts itself is now to my attention. Not sure if its me or weather or not my truck adjusted itself for the recent tire upsize, but the once lag I noticed either is gone in my head, or the PCM adjusted sensitivity to load engine at certain pedal movement, as my truck seems super peppy. Almost to the point where if i had my smaller tires it would be too sensitive all of a sudden, makes me think of the optic bump talk.

Anyhow. Please don't let rebounds and comments take over this thread.

I understand the frustration going on, but please just continue on the conversation. Questions without answers, or questions with varying answers will speak for themselves.

This does not need to become a whose right and whose wrong deal. Everyone here is bringing very good informative input. Keep it coming, please.

 

[gmctd]

Oh yeah, gmctd's repetitive petty insulting is real intelligent too, wonderful attitude for a moderator.

You disguise your stupid statements with insults (I try not to disguise them, so as not to zip right over your head). Like shrugging off the fact that you told everyone that injection pressure doesnt go over pop pressure (IP doesn't maintain higher pressure than pop pressure), and marine injectors will kill your IPs (2750psi injectors will cause excessive wear in the oem stock camring and rollers - marine injectors will cause increased roller\camring wear) , and emphatically telling me I was stupid for implying pressure went over pop pressure (Those pressures mentioned by Goldberg and the Ferm are not typical in a street vehicle, tho I first misunderstood them as indicating they are typical - as S states, if you require those pressures, you will need special camring and roller assembly - thereby implying that stock can't handle the pressure) . And you say but it does set the idle injection pressure (Meaning, DB2\DS4 doesn't inject fuel at 300psi at idle, then at 1850psi at 5000rpm - comparatively, the CRD's run typically ~5000psi at idle, ~23000psi at 5000rpm), like we all didnt already get that and the point was that the pump will run at higher pressures no problem (in some less-informed opinions - marine injectors were designed for turned-up relatively constant-rpm DB2 pumps with marine fuel\advance curves - early on, when DS4 camrings and rollers were disintegrating daily, scrupulous vendors indicated marine injectors should not be used with the DS4).

And you say the frequency impacts the voltage,( Ever hear of a tachometer, Buddy? A varying frequency creates a varying voltage which drives a meter, indicating varying rpm) completely wrong (?????????? say wha ??????????), and try to play it off by spewing other irrelevant terms. (Irrelevant because you don't comprehend them, either - spend some (more?) time in the textbooks, Buddy)
The signal to the FS is not one that the FS analyzes and determines what to do. (True - FS doesn't analyze anything, only responds to applied power) It is an analog power waveform that the PCM digitally synthesized (Flatly FALSE statement - PCM sends a digital Fuel Inject control pulse to the FSD, which is (a) a power driver that applies battery current to the FS solenoid coil via the collectors of the paralleled PNP driver transistors, and (b) a comparator circuit that monitors that current for the changes that result (ELI, Buddy - again, hit the textbooks!) when the flux density changes as armature\plunger begins moving, continues forward motion, and stops as the valve seats - the resultant digital Closure-Time pulse is sent to PCM which starts counting clock ticks for injection pulse width timing - PCM has been counting ticks since sending the injection pulse to the FSD, so CT is included in Injection Pulse Width timing) . Is that incorrect (What do you think)? Does the FS have some digital processor inside of it (No) that reads the peak as a 1 and the low as a 0 and determine that true means move the plunger out (FS is merely a coil, responding to applied power - power on is a 1, coil energized, power off is a 0, coil deenergized)?

How is anyone supposed to have input here (try asking instead of making flatly incorrect statements) if the moderators insult anyone that (repeatedly) says something that differs (from fact) in their (hard-earned hard-learned and experienced) opinion.

For those that are interested, ELI, or Voltage (E) leads Current (I) in an inductor (L), which can be used in describing what happens as flux density in an inductive conductor changes at power-on and power off - the FS is an inductive-conductor wound coil - current and flux density changes in a solenoid coil as the armature begins moving from rest, continues moving, and comes to rest again at end of travel - applied current can be monitored for armature start, travel, or stop, or all three

And, thassa fack, jack.................

 

[buddy]

So we are back to line pressure doesnt go over pop pressure, great.

And the examples noted work completely different than the context.

 

[gmctd]

No, Buddy, it's the uneducated or ignorant "more is better" misconception scenario - "if 1850psi is good, then 2750 is better, and 3700 gotsta be waaay better - hmmm......wunner how much real pressure this baby can crank out" - you know

S set the pop pressures to ensure reduced camring\roller wear - again, in those first years, DS4 camring\roller disintegration at oem pressures was common occurance - and Diesel fuel had way more lubricity component content back then - the IP suffered thru several revisions to cure that - some of which resulted from the cold-hardened extreme-service HD unit the military purchased

So - let's preach the DS4 pumps out over 10k pressure under certain circumstances - "Hoo, boy! More! I want more! I gots ta find me sumbody to build me summa them 10k injectors! Hoooeeee! Orta be right up there with them CRD guys, with them hi-poppers!. Yeeee hah! C'm-oooon, stoplites!'"

Teenie boppers and morons - no, wait...they're the same thing.............

Other than EPA regulations regarding unlawful modifications, that's one reason S is secretive about such proprietary information

Since your persistant contrary input is indicative either of professional trollwork, or you're calling me a liar, call Bill Heath - see what he says about high pop pressures and increased probability of IP damage (altho one example has already been posted - as if you actually do read the responses that appear contrary to your way of "thinking")

Whoever is prompting you doesn't have your best interests at heart, or you're not comprehending the prompting

 

[buddy]

The point is that fuel pressure in the lines is higher than the pop pressure at higher RPM and fuel volume. So if youre going to preach about the idle pop pressure you should also be complaining about increasing fuel rates which will increase your peak pressure.

A digitally generated signal is still an analog waveform, just modulated for an analog component to respond to changes in waveform, and not a setting of bits.

A DVM cannot pick up the electromagnetic field created by current through the wire. I would need an inductive coil to pick that up, like your tach example uses.

 

[gmctd]

This represents a digital signal, beginning at 0v, rising to 5v, falling to 0v - no analog about it, but definite frequency content:
5v_____
0v_____ ________(a)|____________(b)|_________

What is the effective voltage from (a) to (b)?


5v_____
0v_____ ________(a)|||||||_______(b)|||||||____

What is the effective voltage from (a) to (b)?


5v_____
0v_____ ________(a)|||||||||||||||(b)||||||||||||

What is the effective voltage from (a) to (b)?

This represents a 0 to 5v digital signal - no analog about it

5v_____ ''''''''''''''''''''''''''__ ''''''''''''''''''''''''''''''''' __ '''''''''''''''''''''
0v_____ _______(a)| |___________(b)| |________

What is the effective voltage from (a) to (b)?


5v_____ ''''''''''''''''''''''''''____________ '''''''' __________
0v_____ _______(a)|..................|(b)|

What is the efffective voltage from (a) to (b) ?

This represents a 0 to 5v digital signal, no analog about it:

5v_____''''''____'''''''''''''____'''''''''''''____
0v_______|.....|____|.....|____|.....|_____

What is the effective voltage of this signal?


5v_____ ''''_'''''''_''''''_''''''_''''''_'''''''_''''''_'''''''_''''''_
0v_____ _| |_| |_| |_| |_| |_| |_| |_| |_| |

What is the effective voltage of this signal?

The apparent misteaks are not editable

 

[buddy]

Looks kind of like a frequency modulated analog waveform. It rises and it falls and the component responds to the rises and falls.

Now if those upticks were relaying some binary numbering to the FS, like l_ll_l.........l_ll_l...... equaled to 45 and the FS did something because it knew what 45 was then I'd call it digital because its sending bits.

 

[gmctd]

The point is that fuel pressure in the lines is higher than the pop pressure at higher RPM and fuel volume. So if youre going to preach about the idle pop pressure you should also be complaining about increasing fuel rates which will increase your peak pressure.

That is self-evident in that injectors can be calibrated above oem pop pressures - why preach it if hi-pressures can damage the IP - those higher pressures increase camring\roller loading across the board, idle to fwot - systems designed for higher pressures use pumps designed for constant higher pressures
-------------------

A digitally generated signal is still an analog waveform, just modulated for an analog component to respond to changes in waveform, and not a setting of bits.
???????????????
This represents a Variable Pulse Repetition digital signal, beginning at 0v, rising to 5v, falling to 0v - no analog about it, but definite frequency content:
5v_____
0v_____ ________(a)|____________(b)|_________

What is the effective voltage from (a) to (b)?


5v_____
0v_____ ________(a)|||||||_______(b)|||||||____

What is the effective voltage from (a) to (b)?


5v_____
0v_____ ________(a)|||||||||||||||(b)||||||||||||

What is the effective voltage from (a) to (b)?

This represents a 0 to 5v Pulse Width Modulation digital signal - no analog about it

5v_____ ''''''''''''''''''''''''''__ ''''''''''''''''''''''''''''''''' __ '''''''''''''''''''''
0v_____ _______(a)| |___________(b)| |________

What is the effective voltage from (a) to (b)?


5v_____ ''''''''''''''''''''''''''____________ '''''''' __________
0v_____ _______(a)|..................|(b)|

What is the efffective voltage from (a) to (b) ?

This represents a 0 to 5v Square Wave digital signal, no analog about it:

5v_____''''''____'''''''''''''____'''''''''''''___ _
0v_______|.....|____|.....|____|.....|_____

What is the effective voltage of this signal?


5v_____ ''''_'''''''_''''''_''''''_''''''_'''''''_''''''_' ''''''_''''''_
0v_____ _| |_| |_| |_| |_| |_| |_| |_| |_| |

What is the effective voltage of this higher frequency square wave signal?

Measure each of the represented signal types with your DVM, Buddy, see what you get for voltage - a DVM is not the be-all end-all tool of choice when working with microprocessor-managed measurement and control of liquid and gas and temperature and pressure and rotating equipment systems

The apparent waveform misteaks are not editable
----------
A DVM cannot pick up the electromagnetic field created by current through the wire. I would need an inductive coil to pick that up, like your tach example uses.
???????????
My analog tachometer reads the digital signal directly from the Crank Position Sensor, just as the PCM does

Still don't get it, do you Buddy?