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Thread: Hotness in 4 bar map sensors

  1. #1
    ¯\_(ツ)_/¯ burn is weird's Avatar
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    Hotness in 4 bar map sensors

    Hi All,

    So I've pegged my delphi GM 3 bar map sensor now on E85 so need to throw a 4 bar in there.. whats the hotness? my sensor is in the cabin mounted near steering column so heat related sensor drift isn't going to be an issue.

    I've seen "GM style" 4 bar map sensors



    "motorsport" style sensor (i think these are a motorola?)



    or an "omni" branded one



    or even a 3.5bar AEM sensor



    ideal would be to use a GM style one as it would be plug and play, but i dont know if any reputable manufacturers actually make a 4 bar version of its just alibaba knock offs.

    thanks cunts
    Last edited by burn is weird; 09-02-18 at 12:24 PM.

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  2. #2
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    are you saying your emtron doesn't have a 4 bar on board like the haltech elite?

    #emtrontheworld

    (sorry cracka)

  3. #3
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    One of the 5 bar (absolute) sensors here? ; http://theknockbox.com.au/sensors/manifold-pressure/

  4. #4
    ¯\_(ツ)_/¯ burn is weird's Avatar
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    Quote Originally Posted by tim510 View Post
    are you saying your emtron doesn't have a 4 bar on board like the haltech elite?

    #emtrontheworld

    (sorry cracka)
    and thus ends the list of features an elite has over a KV8

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  5. #5
    Arrogant wankeler Slides's Avatar
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    I can probably email you a smiths racing price spreadsheet (the knockbox site elfturbo posted) if you want.

  6. #6
    ¯\_(ツ)_/¯ burn is weird's Avatar
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    All good,

    just ordered a 4 bar Motorola map sensor and an 8 bar variohm eurosensor for EMAP from them. pricing was very reasonable.

    I usually use honeywell MLH for everything but they don't do absolute pressure versions.

    thanks Chaps

    Alex
    Last edited by burn is weird; 09-02-18 at 03:42 PM.

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    Hotness is the Pajero OEM diesel sensors.

    I have four Volvo/ford TMap sensors (for reasons), but having a single bung combined temp and pressure with inbuilt CJ compensation that’s designed for manifold (vibration) mount sounds good to me.

    Plan is to use them pre turbo, post turbo, post intercooler and in plenum, then fuck a few off for shed/projects later.

    Emtron and Elite are comparable for sure, in the same way Jennifer Hawkins and Gina Rindheart are.
    Quote Originally Posted by Bosshoggett View Post
    If your planing to drive this on the road and enjoy it, id suggest a second opinion, someone with a history in Australian Rally or Fink River . If your just playing dyno comps. Then ok

  8. #8
    Arrogant wankeler Slides's Avatar
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    What range are they? I think most of the modern diesels have the combined TP manifold sensors but would be 3 bar absolute?

  9. #9
    ¯\_(ツ)_/¯ burn is weird's Avatar
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    Manifold mount map/iat combined sensors are no good for an ITB rb26.

    Plan is to mount one of the 4 bar Bosch units in the plenum at some stage to use the throttle body flow model in the Emtron.

    It's on the wish list along with dbw itbs if I get around to it this year. Using an E46 M3 throttle motor

  10. #10
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    Quote Originally Posted by tim510 View Post
    are you saying your emtron doesn't have a 4 bar on board like the haltech elite?

    #emtrontheworld

    (sorry cracka)
    Haltech Elite only has a 3 bar map built in.

    1 On-board 3 Bar MAP sensor
    • Supports up to 200Kpa of boost (2Bar / 29psi)

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    Quote Originally Posted by burn is weird View Post
    Manifold mount map/iat combined sensors are no good for an ITB rb26.

    Plan is to mount one of the 4 bar Bosch units in the plenum at some stage to use the throttle body flow model in the Emtron.

    It's on the wish list along with dbw itbs if I get around to it this year. Using an E46 M3 throttle motor
    Might be worth having a chat with Merlin on here, he's recently used them for an DBW ITB conversion and will know the pitfalls.

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    I would use the ti 5 bar map sensor.

    It has good range for both idle and boost, which isnt the case with some other sensors. I assume it will work on Emtron and Link ECU's

  13. #13
    ¯\_(ツ)_/¯ burn is weird's Avatar
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    cossie can you clarify what you mean by that?

    are you saying the sensor/voltage response is non linear, or the low voltage cal limit of some sensors isn't low enough?

    as in 0-100kpa resolution is different to the 100-400kpa range?

    I would have thought a 0-500kpa sensor is the same as any other 0-500kpa sensor, save for temperature induced errors on the cheaper ones, that and I don't really care about the sub 20kpa range.

    while I'm at it, I'm going to install a boost pressure sensor (pre-throttle) which will allow me to use the throttle flow modelling of the emtron.

    question is, if i'm targeting a maximum boost of say 32psi after the throttle, what is a reasonable sensor range for the pre-throttle map sensor? im guessing even with the BOV, on a fast partial close of the throttle plates will cause the boost pressure to spike sharply. question is how high would be a reasonable guess?

    running the stock dual recirculating BOV of the rb26.
    Last edited by burn is weird; 12-02-18 at 11:24 AM.

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    Sorry, took a while to check back.... For a manifold pressure sensor, you have to look at how far into vacuum your sensor can read. Some of the sensors that read higher boost, cannot read as far into vacuum. that is ok if your engine doesn't pull vacuum beyond that point. so for example, I have these numbers...

    Bosch 030 Map sensor has a working range of 10 kpa up to 115 kpa
    their 487 Map sensor has a working range of 20 kpa up to 250 kpa
    whilst their 655 map sensor has a working range of 50 kp up to 400 kpa (with a core measuring range of 70 to 360)

    So an Mx5 I am looking at has 30 kpa at idle
    My 1200 coupe is in the low 20's
    The Viper is in the mid to high 30's

    So, what does this mean.

    well an absolute pressure sensor used for manifold pressure readings reads 0-100 kpa abs is all the vacuum part of the range, >100 is the pressure side (I am sure that I am telling you stuff you already know, but anyhow)

    so a 250 kpa map sensor will not read outside a range of 20kpa in vacuum, and 150ksa of boost (taking off the 100 kpa of atmospheric pressure) 250 kpa = so this sensor will let you read down low enough in vacuum for any of the engines I see accurately, but only goes up to 21.7 psi of boost.

    The 4 bar map sensor will read only down to 50kpa.... but goes up to 300 kpa (43.5 psi).

    Why does this matter, well, when the car goes back to idle, the bottom 20 kpa will not register, so you cannot change fuel of ignition for any changes below 50kpa, as you cannot read the change. It means that it can be challenging to make it idle, and get off idle reasonably as you cannot read the map changes there....

    so that is why the Manifold pressure range is important...
    Last edited by cossie55; 19-02-18 at 08:16 AM.

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    Hi Jamie,

    Thanks for taking the time to write such a long response, I for one found it very enlightening.

  16. #16
    sack riding 10sec rx7's Avatar
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    the TI 5 bar is my goto on anything that needs more than a 3 bar,
    im a cunt
    and apparently i dont know shit...

  17. #17
    ¯\_(ツ)_/¯ burn is weird's Avatar
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    thanks for the reply cossie, I didn't realise that was the case with these sensors. I'm used to honeywell PX2/PX3 which are all 0.5-4.5v ratiometric and are calibrated for the full rated span down to hard vacuum. couldn't get any with a lead time under 4 or 5 weeks. and am tuning next wednesday.

    the TI sensors are outrageously expensive compared to honeywell PX2/PX3. wasn't about to spend $500 on two map sensors when I could get two PX3s for about 45usd each shipped if the ones above aren't up to it.

    these ones: https://au.mouser.com/ProductDetail/...tent=Honeywell

    I ended up with these sensors:


    which use a NXP MPXH6400A sensor. sensing range is 20 to 400kPa for that unit.

    wired it in and it is 0.1kPa off the baro pressure sensor inside the ecu at atmospheric pressure so I'm happy with that.
    Last edited by burn is weird; 20-02-18 at 10:44 AM.

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  18. #18
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    Yeah that is the same as the Haltech 4 Bar Motorsport Sensor. The Haltech docs don't make much sense to me though. Says 99kpa @ 0v but I thought 100kpa was sea level atmo. Wouldn't -29.2inhg be -99kpa? Maybe a typo? Seems to be a trend.

    Calibration
    Volts 0.0 5.0
    kPa 99.0 315.0
    PSI -14.4 45.7
    PSI/InHg -29.2 45.7
    Last edited by Nick; 20-02-18 at 06:10 PM.

  19. #19
    sack riding 10sec rx7's Avatar
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    yeh it should be -100..
    im a cunt
    and apparently i dont know shit...

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    Besides the typo (-99), perfect vacuum cannot he achieved so you can’t calibrate for this


    Sent from my iPhone using Tapatalk

  21. #21
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    that is a really strange way of specifying a calibration of an absolute pressure sensor. giving a gauge pressure calibration for an absolute sensor is totally arbitrary as the sensors reference is vacuum, not atmosphere or a defined sealed gauge pressure reference. any good ecu will have a baro sensor on board if you want to tune to MGP instead of MAP.

    i'd use the MXP datasheet calibration of 0.2 to 4.8v being 20-400kPa abs. which is the actual sensor contained in that unit.
    Last edited by burn is weird; 21-02-18 at 09:14 AM.

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  22. #22
    Purist, whats that? Jason Broadhurst's Avatar
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    It's like that because of the haltech software. it reads gauge in some places and absolute in others. the cal setup is done in gauge.
    Jason Broadhurst

    Someone once asked me if they could use my mower. I said "sure, so long as it doesn't leave my yard"

  23. #23
    sack riding 10sec rx7's Avatar
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    it reads in what ever you tell it to read in.. it does not randomly choose what it wants to read in
    im a cunt
    and apparently i dont know shit...

  24. #24
    Arrogant wankeler Slides's Avatar
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    Quote Originally Posted by cub35 View Post
    Besides the typo (-99), perfect vacuum cannot he achieved so you can’t calibrate for this


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    Most scroll or two stage diaphragm pumps will pull below a pressure that is an effective resolution step on a lot of wide range automotive sensors, well below their effective reading range. You don't even need a turbo pump. Suggesting you can't get an effective zero for output scaling an automotive sensor calibration is incorrect. If you used a turbo pump you would be at a pressure that represented about a millionth or less of a best case automotive sensor/ecu adc resolution bit and easily a billion times less pressure than most sensors would respond to.
    Last edited by Slides; 25-02-18 at 02:52 PM.

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    So your saying you have been able to pull perfect vacuum and calibrate correctly at -100?


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  26. #26
    Arrogant wankeler Slides's Avatar
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    My job is calibration of vacuum and pressure gauges, no there isn't ever perfect vacuum but if you achieve 2 orders or magnitude less pressure than "lowest read" or resolution that is regarded as an effective zero. If anyone buys an off the shelf two stage diaphragm, rotary vane or scroll pump they will have enough vacuum for a zero point on an automotive sensor, realistically an engine won't pull that low anyway so if you had another gauge that read down near 10kPa that would be an effective lower cal point anyway, potentially more linear/less correction in the usable range than using a hard zero and atmosphere as sample points. There are probably old multistage oil sealed piston pumps that would work but I haven't played with any.

    I will probably borrow a small pump and a couple of digital instruments from work to do my own at multiple points in vacuum and boost. The reality is although it's nice to have the thing read near true, due to flow effects at sample points, harmonics/sample frequency and a whole bunch of other stuff like non linearity of fuel pressure regulators at different return flow rates if sensors are within a few % on each sensor it is probably as close as required even with a complex fuel model doing IMP:EMP with fuel rail pressure compensation as there is a lot of stuff going on and combustion inconsistency cycle to cycle is high on spark engines so tolerances for stuff like fuel pressure differential safeties need to be large anyway. Generally a few % AFR will make SFA difference if everything else is right like phase angle/cam/port timing etc and even with runner heat transfer modelling in ecu sofware there is some variability in afr after heat soaking of intake temp sensors anyway. You get as close as you can with moderate effort but trying for lab spec accuracy on most automotive stuff is irrelevant as it won't effect engine performance.

  27. #27
    ¯\_(ツ)_/¯ burn is weird's Avatar
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    Quoting -100kpa mainfold pressure is rustling my jimmies.

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    Hotness in 4 bar map sensors

    Well there you go, my job is Working on pumps (positive and vacuum) and part of that is performing performance and calibration of the instruments that go with them.
    Saying “it’s pretty retarded” wasn’t really necessary.

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    Last edited by cub35; 25-02-18 at 01:14 PM.

  29. #29
    Arrogant wankeler Slides's Avatar
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    You made a short statement in an authoritative fashion which was incorrect as far as the application is concerned. Not looking to pick fights.
    Last edited by Slides; 25-02-18 at 02:50 PM.

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