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2l8uluz 2l8uluz is offline
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Default Manifold vs charge pipe boost figures? - 04-27-2016, 11:00 PM

Does anyone know or can guestimate the difference in charge pipe psi vs manifold? 1,2,3 psi less??

Thanks
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bradsm87 bradsm87 is offline
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Default 04-27-2016, 11:17 PM

Less than 0.3psi at WOT I'd say.
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Jt0407 Jt0407 is offline
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Default 04-30-2016, 12:47 PM

I've had 5 psi difference on a cold day.
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bradsm87 bradsm87 is offline
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Default 04-30-2016, 05:03 PM

Quote:
Originally Posted by Jt0407
I've had 5 psi difference on a cold day.
Impossible. How did you obtain intake manifold boost and was it wide open throttle?
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Velocity26 Velocity26 is offline
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Default 04-30-2016, 05:58 PM

Quote:
Originally Posted by Jt0407
I've had 5 psi difference on a cold day.
I would bet that was more of a variance between the sensors than that big of a pressure difference ... unless your throttle body is not opening completely.
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bradsm87 bradsm87 is offline
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Default 04-30-2016, 07:40 PM

The intake manifold boost sensor only reads up to around 3 psi anyway, so the only way to measure at WOT is aftermarket.
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Terry @ BMS Terry @ BMS is offline
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Default 04-30-2016, 08:45 PM

Depends on the throttle body position. But there is not a lot of pressure drop across the throttle unless it closes 30-40%.


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808AWD325xi 808AWD325xi is offline
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Exclamation 05-01-2016, 09:02 AM

Quote:
Originally Posted by bradsm87
The intake manifold boost sensor only reads up to around 3 psi anyway, so the only way to measure at WOT is aftermarket.
EDIABAS reports intake manifold pressure, boost pressure, and intake air temperature with one API call to the STATUS_SDF2 job. Intake manifold boost pressure can also be displayed with INPA and logged with any EDIABAS compatible tool like Test-O.

Code:
	<JOB>
		<JOBNAME>STATUS_SDF2</JOBNAME>
		<JOBCOMMENT>0x301901 STATUS_SDF2</JOBCOMMENT>
		<JOBCOMMENT>Saugrohr-, Ladedruck und Ansauglufttemperatur fuer N54 auslesen</JOBCOMMENT>
		<JOBCOMMENT>Aktivierung: Klemme 15 = EIN</JOBCOMMENT>
		<JOBCOMMENT>Activation: LV_IGK = 1</JOBCOMMENT>
		<RESULT>
			<RESULTNAME>STAT_PVDKDS_WERT</RESULTNAME>
			<RESULTTYPE>real</RESULTTYPE>
			<RESULTCOMMENT>Druck vor Drosselklappe (nur N54)</RESULTCOMMENT>
			<RESULTCOMMENT>PVDKDS   Einheit: hPa   Min: 0 Max: 2559.9609</RESULTCOMMENT>
		</RESULT>
		<RESULT>
			<RESULTNAME>STAT_PVDKDS_EINH</RESULTNAME>
			<RESULTTYPE>string</RESULTTYPE>
			<RESULTCOMMENT>hPa</RESULTCOMMENT>
		</RESULT>
		<RESULT>
			<RESULTNAME>STAT_PS_IST_WERT</RESULTNAME>
			<RESULTTYPE>real</RESULTTYPE>
			<RESULTCOMMENT>Druck nach Drosselklappe (nur N54)</RESULTCOMMENT>
			<RESULTCOMMENT>PS_IST   Einheit: hPa   Min: 0 Max: 2559.9609</RESULTCOMMENT>
		</RESULT>
		<RESULT>
			<RESULTNAME>STAT_PS_IST_EINH</RESULTNAME>
			<RESULTTYPE>string</RESULTTYPE>
			<RESULTCOMMENT>hPa</RESULTCOMMENT>
		</RESULT>
		<RESULT>
			<RESULTNAME>STAT_TANS_WERT</RESULTNAME>
			<RESULTTYPE>real</RESULTTYPE>
			<RESULTCOMMENT>Temperatur vor Drosselklappe (nur N54)</RESULTCOMMENT>
			<RESULTCOMMENT>TANS   Einheit: C   Min: -3276.8 Max: 3276.7</RESULTCOMMENT>
		</RESULT>
		<RESULT>
			<RESULTNAME>STAT_TANS_EINH</RESULTNAME>
			<RESULTTYPE>string</RESULTTYPE>
			<RESULTCOMMENT>degreeC</RESULTCOMMENT>
		</RESULT>
		<RESULT>
			<RESULTNAME>JOB_STATUS</RESULTNAME>
			<RESULTTYPE>string</RESULTTYPE>
			<RESULTCOMMENT>"OKAY", wenn fehlerfrei</RESULTCOMMENT>
		</RESULT>
		<RESULT>
			<RESULTNAME>_TEL_AUFTRAG</RESULTNAME>
			<RESULTTYPE>binary</RESULTTYPE>
			<RESULTCOMMENT>Hex-Auftrag an SG</RESULTCOMMENT>
		</RESULT>
		<RESULT>
			<RESULTNAME>_TEL_ANTWORT</RESULTNAME>
			<RESULTTYPE>binary</RESULTTYPE>
			<RESULTCOMMENT>Hex-Antwort von SG</RESULTCOMMENT>
		</RESULT>
	</JOB>


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bradsm87 bradsm87 is offline
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Default 05-01-2016, 04:55 PM

The DME does have a calculated intake manifold pressure ("Boost" in MHD logging), but it's not physically measured in the intake manifold. "Boost Mean" in MHD logging is the real measured pressure from the TMAP in the charge pipe. I do not trust the calculated intake manifold boost at all, based on the weird discrepancies in the midrange between the two readings.
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808AWD325xi 808AWD325xi is offline
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Default 05-01-2016, 06:19 PM

Quote:
Originally Posted by bradsm87
The DME does have a calculated intake manifold pressure ("Boost" in MHD logging), but it's not physically measured in the intake manifold. "Boost Mean" in MHD logging is the real measured pressure from the TMAP in the charge pipe. I do not trust the calculated intake manifold boost at all, based on the weird discrepancies in the midrange between the two readings.
I don't use MHD, sorry.


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bradsm87 bradsm87 is offline
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Default 05-01-2016, 07:07 PM

Quote:
Originally Posted by 808AWD325xi
I don't use MHD, sorry.
It's probably the same logging parameter as INPA accesses. If it reads over 3psi when on boost, it's definitely the same calculated value. The sensor physically can not read over 3psi.
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jyamona jyamona is offline
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Default 05-02-2016, 06:18 AM

Quote:
Originally Posted by bradsm87
It's probably the same logging parameter as INPA accesses. If it reads over 3psi when on boost, it's definitely the same calculated value. The sensor physically can not read over 3psi.
This is correct. The model used to calculate manifold pressure above that, based on tmap reading is fairly accurate as well. Easy solution is to run a boost gauge with a serial output for logging, off the intake manifold.

I don't understand why BMW didn't put the sensor in the intake mani tho. There must be a reason because many other german cars have this same 2 sensor setup.


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