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Discussion Starter #1
Ok

I have a different kind of question then what I have seen on here before.

While in hot tune if I stomp on it my HPOP psi will drop to 1600 ish. Now if I step into the throttle I can watch psi build to say 2300 psi until I get to about say 3/4 pedal travel and psi will drop to 1600 ish. If I back out of the throttle psi will jump back up to 25-3000ish psi. From here I try to maintain the psi with pedal travel and not going beyond that point.

I was wondering if anyone might know of what's going on. Also it will do this in the other programs as well ie tow, econo, daily.

Also I can maintain 3000 psi in stock form no tunes. And for the most part I can get this psi up to 5 gear. Once I am in sixth I start to have issues with the above mentioned items.

Any thoughts? Thanks Dave
 

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<-- it's like that
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In a rough way of putting it, beyond 3/4 throttle is basically recognized as WOT by the PCM.

What's happening at WOT is that your chip tunes are calling for higher injector pulsewidth than at less than 3/4 throttle. When pulsewidth is increased, the oil volume demand increases. What happens is you cross a threshold where oil demand is greater than oil supply, and the pressure drops.

The HPOP is a fixed displacement pump. It runs at about 85% the engine speed, and a 17 degree HPOP can pump out on average around 7.2cc's per revolution. Basically the oil demanded by the injectors is greater than what the HPOP can supply at each revolution.

This is why big oil and medium oil mods are so popular. It prevents the HPOP pressure from taking a nose dive, and allows you to maintain an ideal pressure at all times. When HPOP pressures drop at WOT, you aren't getting the full atomization nor the full amount of fuel flow, so you end up with more smoke and less power.

Hopefully this helps explain a little.
 

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Haters Gonna Hate
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so in simpler terms, pocket is saying that you need to upgrade ur hpop, depending on future plans on current injector setup
 

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Seems to be working good! My HPOP, not so much!



I've posted this video a few times today. LOL

But does it look something like this? My HPO pressure drops more at 3/4 throttle than WOT as well. The second video shows that, I go WOT, then have to back out to part throttle, then WOT again.
 

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I can dumb it up.
Take youre garden hose turn it on with a nozzel on the end have the nozzel closed. Feel the hose nice and hard plenty of PSI. Open the nozzel and the PSI in the hose drops the valume is still there the pressure just is not. Pretty much the same thing when you hit the throttle.
 

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Discussion Starter #6
Pocket

Thanks for the explanation, that certainly makes sense and is somewhat the lines of my thinking. Just didn't know what was making the changes to what.

theSLEEPER

Great vids, that is what I see when I am stepping on it. So it sounds like I am back to needing medium oil which is the next upgrade. Once I am employed again:doh:.

One more question kind of off topic a little but what would make the truck shut off when switched to whisper mode? Would a weak pump be a possible cause?

Thanks Dave
 

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One more question kind of off topic a little but what would make the truck shut off when switched to whisper mode? Would a weak pump be a possible cause?

Thanks Dave[/QUOTE]

From any tune to whisper? Mine will do it from exstream to any tune. I can change from any tune and not have problems just when coming out of exstream. I was told the diferance in ICP and having a weak pump causses this.
 

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Discussion Starter #9
Yup from any tune to whisper. Sometimes it will work and most of the time it will not. When it does it smells like unburnt fuel bad. Weak pump certainly is possible.

Thanks for the thoughts and insights.
 

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Yup from any tune to whisper. Sometimes it will work and most of the time it will not. When it does it smells like unburnt fuel bad. Weak pump certainly is possible.

Thanks for the thoughts and insights.
Whisper idle works on most trucks, but a few have to be tweaked.
 
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