where is the sensor that reads vacuum ?

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handsomejackuk
Joined: Sat 18 Jun, 2016 11:35
Posts: 295

  Z3 roadster 1.9
Location: Blaenau Gwent South Wales...

where is the sensor that reads vacuum ?

Post by handsomejackuk » Mon 11 Sep, 2017 19:12

I am trying to work out on an m44 engine where the sensor is that reads manifold vacuum ? is it the mass air flow... ? as i thought that read air quantity not vacuum, or is it all in the same unit ?

zedzedthree
Joined: Fri 29 Jul, 2016 14:16
Posts: 18

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Re: where is the sensor that reads vacuum ?

Post by zedzedthree » Mon 11 Sep, 2017 21:31

The M44 along with M43 engine uses a MAF and the car is not fitted with a MAP sensor,these were more commonly found on earlier EFi systems by other manufacturers.

therealdb1
Joined: Tue 25 Jun, 2013 22:47
Posts: 244

  Z3 roadster 2.0

Re: where is the sensor that reads vacuum ?

Post by therealdb1 » Mon 11 Sep, 2017 22:27

Why do you need to know vacuum?
The MAF gives the mass of air going in and the ECU controls the fuel going in through the injectors and then gets feedback from the lambda sensor(s) to tweak the fuelling accordingly.

deni2s
Joined: Mon 25 Mar, 2013 22:02
Posts: 747

  Z3 roadster 2.8

Re: where is the sensor that reads vacuum ?

Post by deni2s » Tue 12 Sep, 2017 09:28

I know that EVAP system is measuring pressure on testing (at least on M52), and reports leak errors if the pressure is not as expected.

Not sure if same applies to M44. M44 doesn't have the MAP sensor.

handsomejackuk
Joined: Sat 18 Jun, 2016 11:35
Posts: 295

  Z3 roadster 1.9
Location: Blaenau Gwent South Wales...

Re: where is the sensor that reads vacuum ?

Post by handsomejackuk » Tue 12 Sep, 2017 19:35

i just curious as to where the sensor is.... i using the torque app, and can see quite a few sensors and can work out where most of them are... the only one i can't seem to figure out is where it reads vacuum from...

most are pretty self explanatory

throttle position on the throttle body
water temp.. somewhere probably on the cylinder head..
air flow is obv. the maf o2 sensors on the exhaust
intake air temperature on the air box.

heres a pic of my torque app

Image21558953_358177424618677_6608485237815440445_n by handsomejackuk, on Flickr

therealdb1
Joined: Tue 25 Jun, 2013 22:47
Posts: 244

  Z3 roadster 2.0

Re: where is the sensor that reads vacuum ?

Post by therealdb1 » Tue 12 Sep, 2017 22:45

I do not believe there is a vacuum sensor.
Sparing you the physics, gas flowrate is proportional to gas density, temperature and pressure.
Air density is fairly well known so pressure could be calculated rather than measured.
Of concern to me are the anomolies in the screenshot you show.
Throttle says 0% yet you have 1330 rpm showing. That is a high tickover.
Actually your rpm is over 1 million if you accept that the indicated value is x 1000 as shown.
It also shows that the lowest rpm recorded is -64.2 which is nonsense unless you have invented a time machine!
Are you actually trying to find a fault or are you simply playing with a gadget to see what it can do?

handsomejackuk
Joined: Sat 18 Jun, 2016 11:35
Posts: 295

  Z3 roadster 1.9
Location: Blaenau Gwent South Wales...

Re: where is the sensor that reads vacuum ?

Post by handsomejackuk » Wed 13 Sep, 2017 17:49

the reason the throttle is showing 0% is probably because my foot is off the throttle and I am in gear just coasting slowly, as for the -64 rpm it reads that as a glitch, as all the sensors glitch a value of 64 when doing data logging i have seen that a few times... you may be right on the calculated vacuum i did wonder if it was somehow calculated in the ecu... and maybe there is no actual sensor...

yeah just playing with the torque app.. its good to see what the sensors are doing... i not got the afr readings up yet but they will be good to monitor and log.. also its nice to see an actual coolant temperature instead of the guaeg with no temperature readings on there and confirms my thermostat is working as it is at 96 degrees most of the time although i can get it to drop about 3 degrees if i put the heaters on in the car as that takes away heat from the engine, also nice to see the fuel status changing from open to closed loop as engine temperature is reached, and open loop coming in when decelerating and indling... as for vacuum, and other readings i thought it may be good to compare results from anyone else running torque... not sure what my vacuum should be really reading...

i believe also that the first 02 sensor should switch from 1v to 0v and the 2nd o2 sensors should be 0.5v I have yet to log these and would be good to see these in action too... thats my next data screen...

deni2s
Joined: Mon 25 Mar, 2013 22:02
Posts: 747

  Z3 roadster 2.8

Re: where is the sensor that reads vacuum ?

Post by deni2s » Wed 13 Sep, 2017 18:37

There is a fuel tank pressure sensor.

zedzedthree
Joined: Fri 29 Jul, 2016 14:16
Posts: 18

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Re: where is the sensor that reads vacuum ?

Post by zedzedthree » Wed 13 Sep, 2017 20:47

more detail on this fuel tank pressure sensor please???

Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2122

  Z3 roadster 1.9

Re: where is the sensor that reads vacuum ?

Post by Del » Wed 13 Sep, 2017 23:28

Definitely no MAP and/or Vacuum sensor on the M44. I thought these, plus the "boost" reading on your Torque app, relate to more modern turbocharged engines. Things like Torque and Carista (which I use on my Audi) are fairly generic. The M44 is quite "old school" and was not even an OBD II complaint engine - it only has one pre-cat lambda sensor.

deni2s
Joined: Mon 25 Mar, 2013 22:02
Posts: 747

  Z3 roadster 2.8

Re: where is the sensor that reads vacuum ?

Post by deni2s » Fri 15 Sep, 2017 18:14

zedzedthree wrote:
Wed 13 Sep, 2017 20:47
more detail on this fuel tank pressure sensor please???
Google it.
https://www.ecstuning.com/b-genuine-bmw ... 141182581/

zedzedthree
Joined: Fri 29 Jul, 2016 14:16
Posts: 18

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Re: where is the sensor that reads vacuum ?

Post by zedzedthree » Fri 15 Sep, 2017 20:34

Thanks for the link,not used on all engine variant z3 models it would seem. Don't recall it ever having been mentioned on the forum before.

handsomejackuk
Joined: Sat 18 Jun, 2016 11:35
Posts: 295

  Z3 roadster 1.9
Location: Blaenau Gwent South Wales...

Re: where is the sensor that reads vacuum ?

Post by handsomejackuk » Fri 15 Sep, 2017 20:48

Del wrote:
Wed 13 Sep, 2017 23:28
- it only has one pre-cat lambda sensor.
thats good to know as my obd reader does show two o2 sensors all beit the 2nd o2 sensor doesnt seem to show much it does blip a little though...

are you sure there is only one o2 sensor ?

handsomejackuk
Joined: Sat 18 Jun, 2016 11:35
Posts: 295

  Z3 roadster 1.9
Location: Blaenau Gwent South Wales...

Re: where is the sensor that reads vacuum ?

Post by handsomejackuk » Fri 15 Sep, 2017 20:50

zedzedthree wrote:
Wed 13 Sep, 2017 20:47
more detail on this fuel tank pressure sensor please???

same here didnt realise there was a fuel tank pressure sensor.. i wonder if there are custom pids in torque to read that.. or maybe this is only specific to inpa ?

handsomejackuk
Joined: Sat 18 Jun, 2016 11:35
Posts: 295

  Z3 roadster 1.9
Location: Blaenau Gwent South Wales...

Re: where is the sensor that reads vacuum ?

Post by handsomejackuk » Fri 15 Sep, 2017 22:52


Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2122

  Z3 roadster 1.9

Re: where is the sensor that reads vacuum ?

Post by Del » Sat 16 Sep, 2017 09:38

The UK twin cam M44 1.9 definitely only has one pre-cat Lambda - 100% certain.
The UK single cam M43 1.9 (TU) which followed around mid-1999 was OBD II/emissions compliant and had the usual pre and post cat lambdas

handsomejackuk
Joined: Sat 18 Jun, 2016 11:35
Posts: 295

  Z3 roadster 1.9
Location: Blaenau Gwent South Wales...

Re: where is the sensor that reads vacuum ?

Post by handsomejackuk » Sat 16 Sep, 2017 10:28

i not looked at mine underneath so wont disagree with you....but that diagram does show two o2 sensors.. so maybe that is for other markets...

deni2s
Joined: Mon 25 Mar, 2013 22:02
Posts: 747

  Z3 roadster 2.8

Re: where is the sensor that reads vacuum ?

Post by deni2s » Mon 18 Sep, 2017 08:54

Enter you VIN into realoem.com to see that.

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