CCT, CRV, and PERDEL explained.
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Rich... your image below is just a snap shot, right? The values were different in the milliseconds preceding and following this snap shot, right?
Fleet Mechanic
Joined: Mar 2009
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From: Sacramento Delta, CA
OK, I have no business posting in this thread, so forgive me. But for real dummies like me, this helped conceptualize the concept of "Percent Delta" and I can see why it would be a helpful measurement when comparing what 8 cylinders are doing in relationship to an other.
In fact, whether we know it or not, it seems we also calculating a percent delta when we do a compression test and determine the percent variation between the lowest compression cylinder (i.e., the "data") and the highest compression cylinder (i.e., the "reference"). Hope the following helps others like it helped me.
"DELTA_PERCENT comparison
The DELTA_PERCENT comparison compares columns in which the difference is measured in percentages.
One use for DELTA_PERCENTAGE is comparing age. For example, a one year difference for an 85 year-old is less significant than for a 3 year-old, but a 10% difference for each is more meaningful. You can use this comparison with arrays and reverse matching.
<!-- -->Required Columns
<!-- -->The following data source and reference source columns are required:
From:
IBM Information Server Information Center
And oh yeah, I guess "delta" refers to the Greek letter "D" which in this instance stands for "difference" or "change." So "percent delta" could also be called "percent difference"?
In fact, whether we know it or not, it seems we also calculating a percent delta when we do a compression test and determine the percent variation between the lowest compression cylinder (i.e., the "data") and the highest compression cylinder (i.e., the "reference"). Hope the following helps others like it helped me.
"DELTA_PERCENT comparison
The DELTA_PERCENT comparison compares columns in which the difference is measured in percentages.
One use for DELTA_PERCENTAGE is comparing age. For example, a one year difference for an 85 year-old is less significant than for a 3 year-old, but a 10% difference for each is more meaningful. You can use this comparison with arrays and reverse matching.
<!-- -->Required Columns
<!-- -->The following data source and reference source columns are required:
- <!-- -->Data. The value from the data source.
- <!-- -->Reference. The value from the reference source (only applies for a Reference Match)."
From:
IBM Information Server Information Center
And oh yeah, I guess "delta" refers to the Greek letter "D" which in this instance stands for "difference" or "change." So "percent delta" could also be called "percent difference"?
Last edited by Tim Hodgson; Sep 18, 2014 at 01:25 PM. Reason: I know this can't be statistics, because I took statistics three times at UCD and was only able to raise my grade to a D+.
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Hotshot
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From: Puget Sound
...As for whether or not 0.0% is anomalous to my truck or to the scan tool, I have noticed that most enthusiasts who have AE and are running PERDELS also run tunes or programs of one sort or another, whereas my truck has stock injectors and not just a stock "tune" but a stock PCM with zero "tunes". I'm not sure if that has anything to do with what is considered to be a "normal" finding on the forums or not.
The snapshot was indicative of the "average" of the PERDELs. They bounce a bit, but it's not like I watched for a low reading and went "NOW!" just as I hit Prt Scrn.
As for stock vs. tuned, I see plenty of data from stock trucks in different conditions - plus I took many readings on Stinky before he was modified. It may be an AE thing, or it's very possible your truck has been well cared for and the PERDELs are tight as a result.
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From: Puget Sound
Sorry for the absence guys! I lurk from time to time, so I'm not ignoring you. I've been a lazy bum with my free time, feeding my Star Citizen addiction.
Frankenstinky is rock-solid... leaving a rain shadow in the driveway. I launched the boat and it's tied to the buoy... I think I see moss growing on the cover. Our crop of mushrooms gets a regular trimming with the riding mower. Does Lake Mead and Lake Powell need some water? I know where some is.
- Cherries just started, but the weather here has been about as bad as it can get for the crop.
- We had some kind of cherry disease rage through our canyon, so I see a lot more of the Columbia River than I ever have - many orchards have been pushed over and burned.
- With the above (plus a few other issues), our crop will be 20% of normal. We still have to pack the full 6 weeks, but using far less equipment and people.
- Good thing we need far fewer people, they're not available.
Frankenstinky is rock-solid... leaving a rain shadow in the driveway. I launched the boat and it's tied to the buoy... I think I see moss growing on the cover. Our crop of mushrooms gets a regular trimming with the riding mower. Does Lake Mead and Lake Powell need some water? I know where some is.
It's a Van Gogh
Joined: Feb 2010
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From: Elk Grove, CA
To my mind you should run a PERDELS several times. Even when fully warmed up I have seen substantial discrepancies between PERDELS runs. Need to get a feel for the average test.
@Tugly got any biologists figuring out that blight? Only 20% crop is devastating!
And please expand on "far fewer people"?
@Tugly got any biologists figuring out that blight? Only 20% crop is devastating!
And please expand on "far fewer people"?
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From: Puget Sound
Our government, in their infinite wisdom, is "bribing" people to stay home with the augmented unemployment. They make so much money doing nothing that they are in no rush to do the menial jobs involved with packing fruit. We do all of the safe work practices (I convinced purchasing to order a huge load of masks in early March, so we have plenty), so we're not endangering the people who DO show up for work. We take temps before people walk in the door, and an elevated temperature is a "written invitation" to take two weeks off.
If you want to know why it's hard to get things on time or expensive to buy stuff - there it is.
http://treefruit.wsu.edu/crop-protec...herry-disease/
PERDELS are not a test to do when you're just curious - they can be a bit misleading and make you freak out over nothing. When you feel a miss or significant loss in pull, PERDELS help you to focus on the correct cylinder.
If you want to know why it's hard to get things on time or expensive to buy stuff - there it is.
http://treefruit.wsu.edu/crop-protec...herry-disease/
PERDELS are not a test to do when you're just curious - they can be a bit misleading and make you freak out over nothing. When you feel a miss or significant loss in pull, PERDELS help you to focus on the correct cylinder.
New User
Joined: Feb 2021
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Not to hijack a thread but I’m new to AE and want to make sure I’m understanding things. Even warmed up completely for the pid Cylinder x Change Rotational Vel all I get is 0.0 for all cylinders. I’m trying to troubleshoot an injector issue. Truck has a definite miss and is an 02 with 175/30’s. The issue has been persistent since install which was several thousand miles ago.
Any idea on what am I missing about how to use this function?
Any idea on what am I missing about how to use this function?
It's a Van Gogh
Joined: Feb 2010
Posts: 7,812
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From: Elk Grove, CA
Welcome aboard NK34!
0.0 is a bad reading, as you know.
My advice is start a new thread with the background info on your truck's issues. Unlikely anybody will see your post tagged at the end of this thread. Include all mods and symptoms. We'll get it sorted with your input.
Any codes?
0.0 is a bad reading, as you know.
My advice is start a new thread with the background info on your truck's issues. Unlikely anybody will see your post tagged at the end of this thread. Include all mods and symptoms. We'll get it sorted with your input.
Any codes?
New User
Joined: Feb 2021
Posts: 11
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Welcome aboard NK34!
0.0 is a bad reading, as you know.
My advice is start a new thread with the background info on your truck's issues. Unlikely anybody will see your post tagged at the end of this thread. Include all mods and symptoms. We'll get it sorted with your input.
Any codes?
0.0 is a bad reading, as you know.
My advice is start a new thread with the background info on your truck's issues. Unlikely anybody will see your post tagged at the end of this thread. Include all mods and symptoms. We'll get it sorted with your input.
Any codes?