Datalog showing negative psi?

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04RSX
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Joined: Fri Aug 30, 2013 5:15 pm

Datalog showing negative psi?

Post by 04RSX » Fri Aug 30, 2013 10:56 pm

Hello all, brand new to the forum and doing my best to learn here.

04 RSX-S with just AEM cold air

On a datalog I took earlier today my Maf sensor was showing a negative psi the entire time. The value did change but it never went positive, and the graph basically looked like a flatline. Ranging from around -22 to -29
Is this normal?

Thanks for your help. Look forward to learning a lot.
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04RSX
Posts: 5
Joined: Fri Aug 30, 2013 5:15 pm

Re: Datalog showing negative psi?

Post by 04RSX » Sat Aug 31, 2013 2:07 am

Here is a log of a 3rd gear pull at WOT. I'm not sure if the sensors are accurate. The maf sensor actually dropped to -1 on this pull, which is still confusing.

Any thoughts? I checked the settings and it's set appropriately for my elevation.
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omriatoon
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Re: Datalog showing negative psi?

Post by omriatoon » Sat Aug 31, 2013 11:55 am

hi.
i got the same problem.
if any 1 have idea to fix it it will be awsome.
i have civic ep3 type R.
ty!
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Hondata
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Re: Datalog showing negative psi?

Post by Hondata » Tue Sep 03, 2013 7:49 am

The RSX does not have an AFM - what sensor do you mean?

It is just the units showing below atmospheric pressures as negative inches?
Hondata

04RSX
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Re: Datalog showing negative psi?

Post by 04RSX » Wed Sep 04, 2013 2:56 am

Hondata wrote:The RSX does not have an AFM - what sensor do you mean?

It is just the units showing below atmospheric pressures as negative inches?

I typed M A F by mistake and it corrected it to AFM. My mistake.

Yes, my MAP (/PSI) is reading negative numbers, usually around -15, but "raises" to about -1 when I floor it.

I was reading that the car sucks in air, and is actually creating a vacuum, which makes sense other than that it raises when I floor it. I would think more throttle would induce more air vacuum. I am a newbie when it comes to tuning, so I appreciate your input.

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Hondata
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Re: Datalog showing negative psi?

Post by Hondata » Wed Sep 04, 2013 8:35 am

Change your units. There is a bastard unit '"/psi' which is commonly used in the US which shows below atmospheric pressure as negative inches and pressures above atmospheric as psi.
Hondata

04RSX
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Re: Datalog showing negative psi?

Post by 04RSX » Wed Sep 04, 2013 2:55 pm

Alright, I changed it to kPa. I live in Oklahoma though, not sure how far below sea level I live. Lol. Will test it out later.

I appreciate your help.

Zperformance
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Re: Datalog showing negative psi?

Post by Zperformance » Wed Jan 25, 2017 6:07 pm

(-) numbers are vaacum. + number is actual boost

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