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jtdm map sensor?

Guys what is the max boost pressure that the oem map sensor can handle?
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3 bar absolute, or 2 bar boost.
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From two characteristic curves for "Bosch" MAP sensors could be concluded that measurement range is little wider on both sides. For example: ECU calibration interval for OEM MAP sensor is between 400mV and 4644mV what means between 200mbar and 3000mbar.
But 3.0 OEM MAP voltage response is from approx. 300mV to 4850mV and measurement range could be linearly wider with proper recalibration in map.
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thanks guys anyone got a bosch part number for 3.5 bar map or even 4 bar
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0 281 002 456: 0.5-3.5bar (uses characteristic curve type 2)
0 281 002 576: 0.5-4.0bar

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Quote:
Originally Posted by dusanGT View Post
0 281 002 456: 0.5-3.5bar (uses characteristic curve type 2)
0 281 002 576: 0.5-4.0bar

perfect thanks
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Bosch specs state the operating range to be 200mb @ 0.3v to 3000mb at 4.8v, so why the manufactures use a very different scaling is something that I have pondered for a while. Perhaps they are erring on the side of caution and actually under boosting. I have noticed that the atmospheric pressure produced by the ECU does not match up with the TMAP sensor if you use the standard 0.3-4.8v range. I have seen this on every car I have had the interest to look at, so I usually lift the bottom voltage to 0.4v and this to me suggests that the sensor may not indeed have a better range than stated. I have also seen voltages upto 4.85v but never as high as 4.9v.
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My former and original MAP sensor for GT JTDm (0281002845) had voltage range 400mV-4650mV for pressure range 200mbar-3000mbar, according to ECU data. New 0281002456 is 500mV-4500mV and 500mbar-3500mbar.
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That is not correct for the 3500mb TMAP. If you search through Bosch, they have PDFs with specifications for all their sensors, they state the minimum, typical and maximum voltages for the sensor.

Low (min/typical/max) 0.25v, 0.30v, 0.35v
High (min/typical/max) 4.75v, 4.80v, 4.85v

So the typical range would be 0.3v-4.80v for the 500mb-3500mb range.
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For 3.5bar MAP (0281002456) is related "Characteristic curve 2". It is straight line function:
Voltage = (8 x Pressure - 1)/6
or in inverse sense:
Pressure = (6 x Voltage + 1)/8
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Okay and where are you getting that information from; if the answer is not a Bosch data sheet then I'm not interested, if it is a different one the the data sheets I have, please post a link.

And if you do those calculations one way then revers them, they don't even give the same answer, so clearly wrong.

Strike that, I have a fat finger and apologise but the first paragraph standards.
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Please, carefully read this:
Manifold air pressure - S4wiki
and analyze diagrams on page 36 of document:
http://nyet.org/cars/info/Map_Sensor...cification.pdf
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Okay, apologies.
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For the common case:
voltage "V" is:
V = (Vmax - Vmin)/(Pmax - Pmin) x (P - Pmin) + Vmin
and pressure "P" is:
P = (Pmax - Pmin)/(Vmax - Vmin) x (V - Vmin) + Pmin

It is interesting that before the linearization map for the MAP sensor, in ECU file can find two "indicative" numbers, which could be Vlower and Vupper voltage limit of MAP sensor... In my case they are: 00041 and 00993 i.e. 200mV and 4853mV, if factor of multiplication is 4.8876.
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those are signal plausibility limits.
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@yan.ko
What is behaviour of MAP sensor in upper and lower zones between mentioned plausibility limits and "standard" well-known diagram limits:
a) with some kind of non-linear "voltage-pressure" relation or
b) with non-reliable "voltage-pressure" relation?
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If you exceed those values you go into limp. The voltage to pressure conversion is a 2x2 map with the voltage and mb.
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Not sure, but outside of those plausibility boundaries you'll get sensor error. They are there for (almost) every sensor. Voltage as well as digital value boundaries.
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Signal voltage is digitally presented by range from 0 to 1024 (0.0V to 5.0V). Factor of 4.8876 is based on 5V/1023... Btw, factor of 5/1024=4.8828125 look like more logical value...
Maybe MAP could be enough accurate within mentioned limits (00041 and 00993 i.e. 200mV and 4853mV) for rare cases of large boost peaks, based on assumption of linear behavior of MAP in this voltage/pressure range.
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I have tried to do that on few cars... but the results are mixed.
In most cases fun stops around 3080mbar. But some MAP sensors can go up to 3150...
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Quote:
Originally Posted by dusanGT View Post
Signal voltage is digitally presented by range from 0 to 1024 (0.0V to 5.0V). Factor of 4.8876 is based on 5V/1023... Btw, factor of 5/1024=4.8828125 look like more logical value...
Maybe MAP could be enough accurate within mentioned limits (00041 and 00993 i.e. 200mV and 4853mV) for rare cases of large boost peaks, based on assumption of linear behavior of MAP in this voltage/pressure range.
yes, there are 10bit ADs in the C167CR microprocessor as far as I remember, so /1024 (2^10) and *5 (because of 5V) is straightforward and logical. What I ment is so to speak signal meaning value. ECU checks if not only signal voltage is within the limits but translated meaning (boost -in this case) is within specified limits. And now I'm not talking about boost limiter maps, but sensor plausibility check.
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It is /1023... Because you have 1024 discrete values (first is 0 and last is 5V). And they are evenly spaced out by 1023 "gaps".
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Hi,
4B map sensor linearization 0 281 002 576
I used
0,5V (102 in map linearization) -> 0,5b
4,5V (921 in map linearization) -> 4b
correct? For this mas sensor "full pressure" is @ 4.5? 5V?
Compering to stock map sensor... without startig engine
stock shows pressure: 998
new 4b with such like above linearization: 1006 ... small difference... hmmm
br,
Alfiarz
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