PW @ RPM? - PowerStrokeNation : Ford Powerstroke Diesel Forum
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post #1 of 50 (permalink) Old 10-08-2007, 05:12 AM Thread Starter
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PW @ RPM?

After playing for the last two days, I am curious as to what your trucks PW is @ different RPM points. Oil pressure I don't care about unless you can't maintain 3000psi. What are you seeing @ 3000, 3500, 4000 and so on. Trying to understand why the PCM is supposodly "pulling" PW out at higher PRM.

If I know what is called for at a specific point, and I get that, the computer just goes plum stupid and that is not really what is happening?
Electric signals are pretty simple to see and understand.

Marc

2000 F350 CC dually auto
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post #2 of 50 (permalink) Old 10-08-2007, 06:34 AM
 
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Re: PW @ RPM?

The PCM pulls PW back as the rpms go up because the same PW will be over a greatly incrased number of degrees of crank travel. So now for example you would have the injetor still fireing with the piston half way down at a higher rpm at the same PW as you have at lower rpm. Supposedly some can tune around that and make the PW stay higher at the higher rpm ranges but at a point you are just dumping fuel in that won't be makeing any power. And at a certin rpm you will actually be blirring the lines so far that you will have multiple injectors fireing at the same time. Then you are really going to have issues holding ICP.
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post #3 of 50 (permalink) Old 10-08-2007, 12:21 PM
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Re: PW @ RPM?

Just be sure you don't get your intel from the PCM itself (ie scanner data) and you actually scope the injector wires themselves.

Other than that, there's nothing "supposed" about it. And nobody on this planet can tune around it, because it's a physical certainty.
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post #4 of 50 (permalink) Old 10-08-2007, 02:11 PM
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Re: PW @ RPM?

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Originally Posted by UNCOOL View Post
After playing for the last two days, I am curious as to what your trucks PW is @ different RPM points. Oil pressure I don't care about unless you can't maintain 3000psi. What are you seeing @ 3000, 3500, 4000 and so on. Trying to understand why the PCM is supposodly "pulling" PW out at higher PRM.

If I know what is called for at a specific point, and I get that, the computer just goes plum stupid and that is not really what is happening?
Electric signals are pretty simple to see and understand.
Have you raised all the limiters?

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post #5 of 50 (permalink) Old 10-08-2007, 07:03 PM
 
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Re: PW @ RPM?

First of all, are you seeing what is commanded, or what is actual PW.
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post #6 of 50 (permalink) Old 10-09-2007, 06:18 AM
 
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Re: PW @ RPM?

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Originally Posted by Charles View Post
Just be sure you don't get your intel from the PCM itself (ie scanner data) and you actually scope the injector wires themselves.

Other than that, there's nothing "supposed" about it. And nobody on this planet can tune around it, because it's a physical certainty.

Charlie, What are you seeing difference between the scanner reading and actual scopeing the injector wires?
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post #7 of 50 (permalink) Old 10-09-2007, 03:17 PM
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Re: PW @ RPM?

The scanner (PCM) data might say 4ms when the actual pulsewidth has actually already started falling.

Obviously the actual width is less anyway, but the discrepency will grow at times.

Have you never seen scanner data that was total trash before? Like ICP data while you're looking straight at the ICP on the mech gauge and it's clearly lying to you?

That data will go stupid when things get out of bounds for lack of a better way of saying it.
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post #8 of 50 (permalink) Old 10-09-2007, 03:27 PM
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Re: PW @ RPM?

what kind of actual pw difference have you measured between a modded idm and a stock idm?

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post #9 of 50 (permalink) Old 10-09-2007, 05:17 PM
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Re: PW @ RPM?

There wouldn't be one. The difference is in armature latency not actual signal start/end time. The signal starts/ends the same only the strength is different resulting in greater "effective" pulsewidth, or time that the armature is up and fuel is being injected.
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post #10 of 50 (permalink) Old 10-10-2007, 12:38 AM Thread Starter
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Re: PW @ RPM?

So no matter what is called for, you will never get it?

When I ask for PW to be 3.6ms @ 4000rpm I really don't have it.

Humm? guess a powerstroke 7.3 will never be competitive on the pulling track with every 12v crankin the power out at 4500 per the rules, and tuned Duramaxes makin darn nere 500 hp. we will never be on top.

Sure wish DI would build a pullin truck that could turn the R's down the track at full fuel.














Well F%ck, might as well sell this limited POS and go buy a 12v.

Marc

2000 F350 CC dually auto
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