Boost PIDs give 2 different readings?

[GTPDisaster]

I looked in the tip&tricks section of the help to set up a PID to measure boost pressure, I used the first one PID.11 and the numbers im gettin go from -10 at idle to 7 at 50kPA and 4400rpm. Which didnt make sense so then I used the 2nd one which gives me a reading of -24 at idle to -8 at 50kPA and 4400 rpm.

I put them in like the file said. So I think there must be something physically wrong with the motor but even if thats true shouldnt the numbers match?

[Bill@HPTuners]

care to post a scanner log?

[GTPDisaster]

Attachment 9267
Yea this is the latest one, its kind of a mess I know. Im tryin to see at much info as I can right now because as you can see my fuel trims and stuff are crazy.

[Bill@HPTuners]

seems ok to me, can you give me a specific frame to take a closer look at? Otherwise it seems perfectly fine to me.

[Bill@HPTuners]

for instance, frame 356 is 140kpa or 20.31psi-14.5 so should read 5.81 unless your calc pid is incorrect it should be fine.

[GTPDisaster]

I used both ways that were in the tips to calculate the pressure. I called one boost and the other boost2, the numbers they show do not match. I was also under the impression that when I subtracted the 14.7 from the map sensor reading that would give me just the boost pressure, you re saying I need to take an additional 14.5 from that? Im a little confused

[GTPDisaster]

"Solution 2
This method is similar but uses [SENS.30.IMP]-14.5 as the function. You shouldn't have to change your histograms, charts, gauges etc. as they all log as sensor based by default."

Copied this from the online help, isnt that the 14.5 you were talking about?

[GTPDisaster]

One more for ya if you dont mind.

Im looking at the scan I posted at frame 356 on the primary table is reads MAP(SAE) as 140kpa, when I look at the histogram and the chart for that same frame it has the MAP(KPA) at 50kPa and 45.6 respectively. Maybe this is a dumb question but why is that? This is a screen of what im talking about:Attachment 9269

[Bill@HPTuners]

One more for ya if you dont mind.

Im looking at the scan I posted at frame 356 on the primary table is reads MAP(SAE) as 140kpa, when I look at the histogram and the chart for that same frame it has the MAP(KPA) at 50kPa and 45.6 respectively. Maybe this is a dumb question but why is that? This is a screen of what im talking about:Attachment 9269

Sounds like you screwed up your custom pid's, my recommendation would be to delete them & start over.

[Bill@HPTuners]

Copied this from the online help, isnt that the 14.5 you were talking about?

yes.

[GTPDisaster]

I could have messed it up not arguin that at all, but even on my VE histogram there is no data for anything above 50kPA. I havent changed that histogram it is just how it was when I got the unit. Plots LTFT against MAPvsRPM.

Even on the chart it has MAP in kPA listed at 45.6 when on the table its 140.0 kPa on the same frame. I dont kno if you can see that from the pic its kinda small, but I dont know how I couldve messed that up. Ive just read through the help files again and I dont even see a way to change those.

Lookin back at my other logs there is no data listed for anything over 50kPa, it shows up on the primary table but its not in any of histograms, custom or not.

Last the boost measurement I get using solution 1, pid.11.imp-14.7 does seem to make sense @ 5.81psi but at the same point solution 2 is showing -8.96psi, I just redid the pid read the directions and watched the flash show on how to set up a custom PID.

Any idea? Is there somewhere else I should post this?

[bilemke]

I use and can confirm the following for boost on a GTP:

[PID.11.IMP]-14.503773773020923

[GTPDisaster]

Yea I guess I was a lil thrown by the negative numbers at idle and because it didnt match the second method that used the sensor directly.

Any idea why none of my histograms show anything past 50kPa even though its clearly in the table? If you look at the scan I posted, at frame 356, as bill mentioned, it shows a MAP value of 140kpa, if you look at histogram 3 the VE histo, there are no values for anything past 50kpa what would cause that?

[bilemke]

Are you using sensor for MAP or PID for MAP in the histograms?

[JFDugal]

Are you using sensor for MAP or PID for MAP in the histograms?

x2. Double check your custom histogram parameters. Looks like you based it off of one of the fuel trim / VE histograms, so compare your setup to those.

Also if you don't want the negative boost numbers, use the relational operators to filter them out.

[GTPDisaster]

The problem was my first boost PID the [PID.11.IMP]. I deleted all of my custom PID as bill mentioned, and the histos worked fine. Then I remade the above PID and it limited all of the info in my histos to 50kpa, then I deleted it again and they all came back. I guess im doing something wrong but im not sure what it is, I followed what the help said under tips&tricks line for line. I used the second one [SENS.30.IMP]-14.5 and that seems to work ok, as far as I can tell anyway. At least the info is showing up

[Bill@HPTuners]

Change the sensor from manifold air pressure to blank and it should be ok, I'll revise the help file when I get a chance.