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Which Reading to trust?

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Old 11-07-08, 03:45 AM
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Which Reading to trust?

I recently installed a few Defi-link BF gauges in the rex.
The boost reading on the pfc after a hard run is 1.01bar, however on my defi gauge its about 1.2bar!

I'm presuming the Defi is correct? (although I seriously hope not)
Old 11-07-08, 04:11 AM
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I'd borrow a vacuum pump with pressure gauge and test it.

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Old 11-07-08, 06:22 AM
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The PFC stock map sensor calibration is not accurate - it tends to under-report high boost. I would calibrate it. Search in the PFC section for instructions.
Old 11-07-08, 06:48 AM
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Are you measuring boost in different areas of the system?
Old 11-07-08, 08:41 AM
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Originally Posted by moconnor
The PFC stock map sensor calibration is not accurate - it tends to under-report high boost. I would calibrate it. Search in the PFC section for instructions.
Makes sense, thanks.
The car needs a re-tune as its running a full exhaust now. Would resetting the pfc be of any benifit? Would be good to re-do the idle test as its idleing rather high since the midpipe was fitted.

Last edited by Ceylon; 11-07-08 at 08:45 AM.
Old 11-07-08, 09:45 AM
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As royal suggested, different areas of the system will have different pressures. Right after the compressor, it'll be highest, then through he intercooler you lose a couple psi at least, and through the pipes, there's some pressure loss from temperature change and turbulence, then get to the plenum and feed the signal down a long vacuum hose and you're bound to get a somewhat off reading.
Old 11-07-08, 10:04 AM
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Originally Posted by Troux
As royal suggested, different areas of the system will have different pressures. Right after the compressor, it'll be highest, then through he intercooler you lose a couple psi at least, and through the pipes, there's some pressure loss from temperature change and turbulence, then get to the plenum and feed the signal down a long vacuum hose and you're bound to get a somewhat off reading.
I appreciate that, but 0.2-0.3bar (2.9-4.4PSI) above the PFC is quite large. They both pickup from the same place near the UIM iirc. i'll take a look when I finish work.

Thanks for the replies guys.
Old 11-07-08, 10:31 AM
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Your Defi gauge should be more accurate than the stock sensor. For instance, I have Trust boost meter and it indicates exactly the same pressure as the Omori I had installed before.

My PFC was set by an apexi ppower excel last week and he had to set it at 1.0 bars to have 0.9 of effective pressure.

Anyway if you modified your exhaust you'll definitely have boost pressure elevation. You should indeed have your PFC properly retuned.
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