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How does the ecu measures boost?

 
Old 03-07-2019, 05:39 AM
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Matute
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Default How does the ecu measures boost?

Hi guys

do you know how the 993 tt ecu gets info about the boost ? As far as I know this car has no map or manifold pressure sensor. The only boost measurement is for the digital dash gauge. But I dont see that going to the ecu in anyway

thanks
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Old 03-07-2019, 11:07 AM
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Vincent C.
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there is a boost sensor in the intercooler...you have to unplug it if you remove the intercooler....
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Old 03-07-2019, 02:15 PM
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Thank you, but isn't that just the inlet air temp sensor?
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Old 03-07-2019, 02:24 PM
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it's called a temp sensor, but it's what the ECU uses to read boost....
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Old 03-07-2019, 05:02 PM
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Thank you Vincent only one more question. Do.you know if it measures directly boost or just temp and uses some data table in the ecu to transform that to theoretical boost?

do you know what pin at the ecu this sensor goes to?

thank.you
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Old 03-07-2019, 06:00 PM
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that temp sensor generates a signal that the control unit reads....
that sensor is only for the 993 turbo....the control unit takes that
signal and calculates temp and boost.....
that's what hurt the turbo car.....
intercooler would get heat soaked from prolong boost runs
and the control unit took power away for safety....
pin 16 goes to pin 1 of sensor
pin 34 goes to pin 2
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Old 03-07-2019, 08:23 PM
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Thank you very much for all your info
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Old 03-07-2019, 11:06 PM
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Default Sensor



There is no “boost sensor” on intercooler! The boost sensor, is an electronic sensor mounted on drivers side of engine, off of front where the left side diverted valve is.
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Old 03-08-2019, 05:30 AM
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Yes but that boost sensor is not connected in any way to the ecu. It is just used to display boost at the digital dash. What I'm trying to find out is how the ecu realizes if there is actual boost or not.
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Old 03-08-2019, 09:58 AM
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i just explained it to you !!!
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Old 03-08-2019, 09:59 AM
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overboost is wrong ....he is showing you what works the gauge..
i explained what the ECU reads....
107-45 of the PET
#12 is in the intercooler, it called a temp sensor,
now go to your 993 turbo workshop manual and it will
explain how it works !!!
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Old 03-10-2019, 02:15 PM
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Put in a manual boost gauge instead.

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Old 03-19-2019, 10:59 PM
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I always wondered that and I thought the MAF was the only device that besides reading air flow, interpolate for "boost" as signal. I thought the 993tt had some kind of map sensor in the back?(some cars use MAF as primary fuel adjustable mixture and also has a map sensor from factory). Temp sensor has all combustion engines AFAIK and is used to correct the timing and I think as well some fuel but not so sure in the last one or maybe depends on what application/manufacturer developed the system.

Vincent C. I think I understand what you want to say, although is not a propper boost sensor it sense the temp and the DME is mapped/calibrated at some point that read the temp and interpolate as boost by the temp it develope under boost and other factors.

I might be totally wrong though.
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Old 03-20-2019, 08:32 AM
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The DME reads the input of the Air Mass Meter along with the Temp Sensor....From there it has been programmed to calculate the boost in the motor....
The DME is 993 Turbo Specific and the Temp Sensor is Turbo Specific.....What Overboost showed is the sender that generates a signal, that goes to the Central
Informer, it generates another signal that can be displayed in the Onboard Computer....It does not go to the DME....There is no MAP Sensor on this Motor....
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Old 03-27-2019, 02:25 PM
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FWIW the stock digital boost gauge does not show vacuum. I have an analogue gauge like in the video with tubing that, goes somewhere I don't know (intake manifold???), and it shows vastly different values than the stock gauge. However, they do both ease there way to .8 bar during wot.
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