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VE Calculations and Lean Codes

  • Wood
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03 Jan 2019 21:07 #25926 by Wood
VE Calculations and Lean Codes was created by Wood
I just watched Paul's newest video. Great video, amazing content! Could someone give me a little more insight on VE calculations and how to use them in troubleshooting. I'm not sure if I'm quite catching on. So if you were running lean at WOT, you plug in your engine load and MAF readings and your VE calculations turned out to be good.....then you would focus on a fuel delivery issue? is that correct?

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06 Jan 2019 14:51 - 06 Jan 2019 14:54 #26013 by Andy.MacFadyen
Replied by Andy.MacFadyen on topic VE Calculations and Lean Codes
Yes I would be considering a fuel delivery issue.
What vehicle, engine, mileage and year ? Flex Fuel ????

"Through the grease streaked windows
Of an all night cafe

We watched the arrested get taken away"

( Bernie Taupin )

Last edit: 06 Jan 2019 14:54 by Andy.MacFadyen.

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06 Jan 2019 17:37 #26016 by Wood
Replied by Wood on topic VE Calculations and Lean Codes
No vehicle in particular. Sorry, that post wasn't thought out very well. I just watched Paul's latest video on lean codes and a dirty MAF and I had so many questions rattling around in my head that I didn't know where to begin. The O2s were lean at WOT so he mentioned it could be either a fuel delivery issue or a dirty MAF, that I understand from reading his book. He mentioned that the VE calculations were low so there was no need to read fuel pressure. So you can use VE calculations to determine your direction of approach? Lean O2s @ WOT and bad VE = dirty MAF? Lean O2s @ WOT and good VE = fuel delivery issue? I know I've seen him test MAFs with scan data by doing a snap throttle test and looking to see if the MAF voltage goes above 4 volts. Is that only valid with a inoperative MAF sensor and not a dirty one? I guess I need to brush up more on MAF sensors and how to troubleshoot them. Is your troubleshooting steps different with a MAF that's dirty compared to one that is not operating properly?

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06 Jan 2019 22:29 #26030 by Tyler
Replied by Tyler on topic VE Calculations and Lean Codes
Wood, I have a flow chart I found in a training class manual several years ago that might help. I find that it very neatly explains ScannerDanner's approach, while also integrating Calculated Load.



Hopefully that helps! As far as my diagnostic approach is concerned, Load and VE are the same thing. Both are based primarily on the MAF, and both be low in the case of a underreporting MAF or a engine breathing issue. Both will show high if the engine is breathing correctly and the MAF is reporting correctly. Neither can distinguish between a misreporting sensor and a breathing issue on their own.

There's another thread we had going in the Diagnostic Tools section that's also worth reading. Tons of testing and good info in there:

www.scannerdanner.com/forum/diagnostic-t...s-absolute-load.html
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08 Jan 2019 10:58 #26056 by Andy.MacFadyen
Replied by Andy.MacFadyen on topic VE Calculations and Lean Codes
One factoid picked up from the internet on a throttle snap a gasoline MAF sensor signal e should follow almost exactly the same pattern as the MAP sensor signal.

"Through the grease streaked windows
Of an all night cafe

We watched the arrested get taken away"

( Bernie Taupin )

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08 Jan 2019 11:50 #26060 by Wood
Replied by Wood on topic VE Calculations and Lean Codes
Awesome, thanks Tyler. I've been diggin through that thread you sent me and there is a lot of good information in there and that flow chart really helps me organize my thought process during these faults.

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09 Jan 2019 11:15 #26091 by Tyler
Replied by Tyler on topic VE Calculations and Lean Codes
No problem! There's another thread that Noah started that may make for interesting reading:

www.scannerdanner.com/forum/scannerdanne...8-low-power.html#933

Short story, I installed a intake restriction in a Chevy truck, and that flow chart pinned it down. B)
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09 Jan 2019 16:54 #26095 by Noah
Replied by Noah on topic VE Calculations and Lean Codes
Blast from the past!

"Learn, apply, repeat."

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