Alright guys i saw in the drag section a new product from yoparts in regards to there map sensor. It is interesting to see this is not your regular map sensor as it op amp circuitry tied into the sensor.

This sensor claims to be able to compensate for temperature and also in mention in the speed density system that there will be no change due to elevation.

I am trying to grasp this concept and understand that the compensation is the due to the temperature of the unit itself also the comments about elevation?

The only reason i see this fit is that the void on the one side of the silcone diaphram is sealed and due to temperature it will change its density causing improper voltage comapred to actual pressure.

Now how does the elevation tie into all this?

 

Here is a better question....

Why would you need this?

Last I knew the EMS does all the calculations for compensation. Now you throw in a new variable and things change. As we all know the MAP sensor is one of the most important sensors on our cars.

 

Yes the map sensor mimicks the injectors pulse width sensor pattern because it is its primary referance. I noticed that this is not only in the yoparts map sensor but also almost identical product discreption as omnipower and the more i search i see motorola having op amp circuirty and other map sensors.

The thing is are these silicone differential map sensors or silicone sealed map sensors. I have always thought they were sealed sensors and thats where primairly this temperature compensation would come into play. Although elevation change is inevitably seen by all map sensors.

I am personally looking for a better explination on the matter.

Also tepid1 ems is only as accurate as the sensors. If a paticular value is inaccurate such as iat or ect it is the tuners job to interpolate these values vs. other data to correct the mapping. This is always a part of tuning but with more linear, accurate, stable sensor values this makes tuning much easier and predicable.

 

Alright well i did some more research and found a data sheet on freescale and also a patent sheet. In the freescale diagram you can see an absolute referance and in the patent describes the temperature compensation.

http://www.wipo.int/pctdb/en/wo.jsp?...2&DISPLAY=DESC

http://www.freescale.com/files/senso...t/MPX4105A.pdf

 

OP,

You are correct in that your EMS is only as good as the sensors that are tied to it. Although, in the same respect, do not try and have one sensor do the job of 3. Manifold pressure sensors are only a portion of the equation of speed density based systems. Your major three (excluding ECT) are manifold pressure, intake temp, and barometric pressure / or exhaust manifold pressure (eMAP).

If you have your calculations and compensation tables set up correctly in your software, with any variety of these 3 sensors mounted in the proper position you will have all you need for a engine to run properly at any altitude or temprature (all things considered).

 

can't blame the guy for wanting to use a better, more technologically advanced sensor, or at least understanding why it would be beneficial to use.

 

But is it really better or is it just maketing BS?

My thoughts are that it's just crap. Yes a sensor with great resolution is going to be better, but this temperature compensation crap is just that.... crap.

A sensor is sealed so that it can be used in all elements, not for temperature compensation reasons.

With the small pressures that we are seeing, temperature doesn't that large of a roll. Yes, even 50 psi is a small pressure. When you start talking 2000+psi then you can talk about how temp plays a role with pressure. Also remember that volume has a role with this as well.

IMO this sensor is not necessary. I'd rather use a Honeywell or MSI (as everyone else knows it as an AEM sensor) any day.

Look for something that has good resolution, is accurate (I like the + - .1% sensors), is linear, sealed, and is good with vibration.

 

sander, i agree with you in your post but i am putting this up for discussion purposes in regards to the features expressed with these sensors. I am not saying that this is temperature compensation that would interfere with the function of the intake air temperature sensor. What my thoughts were was that it was based on the dry air on the back side of the silicone diapghram if you read through my posts properly. Now i understand how the barometric is inplace with these sensors, but i am questioning functionality of the temperature compensation. This is what i mainly wanted to discuss.



Maybe the accuracy is dependant on the temperature compensation? I realize this is a sealed unit but the air behind the diaphram can be influenced by temperature. Understand what i am getting at?

 

there is a air pressure sensor inside honda ecu's which determine your elevation and compensate for it. without that honda would have to have a different ecu for all elevations.

 

I understand what you are trying to discuss here, and I'm always for a cool new over-engineered idea. Although, whether I think it makes a difference or not is almost irrelevant. A guy who I respect highly put it to me like this when I actually asked him about theoretical problems with cam advance tables and possible mechanical issues that may not let the cam advance and cycle on to the wrong table and F your mixtures up (using motec 4D axis). Unrelated to what you talking about with the map sensor but the point remains.

He said:

(to the effect of) "Well, ok maybe there is a problem with this in theory. BUT what problem does it CREATE in real life? Are you losing power? Are you having problem between shifts? Is the car running poorly in different temp / alt situations?"

I said:

"No not really, just always wondered about it."

Then I had thought to my self, do not try and create problems that do not exist. Engines are REALLY simple air / heat pumps. You can spend all the money in the world on fancy sensors, but as long as your making the power that you need to and the car "feels" and "looks" correct on a dyno sheet or in a race situation. Then whats the point? Same way I feel about people that speak of needing "EXTREMELY high resolution fuel tables" You don't REALLY need it in most situations, but it is cooler to play with.


So, yeah man it really might make a difference but I wouldn't likely buy one for any car that I setup. Sorry if that's not what your looking for. But it is my .02 on the issue. I would be interested to see a back to back pressure readings plotted over a graph VS a honeywell or whomever else's sensor.

-sander

 

sander i am not one to dismiss something as this, but for your information this seems to be popular with all popular map sensors offered to the honda community weather they are just all housed motorola sensors or not, but comapnies such as yoparts,hondata,motorola series,omni power,i beleive gm sensors, and many freescale pressure sensors.

I am curious in its operation for temperature compensation regardless if the theory is significantly influecing real world practice or not.

Thanks mike93eh2 for the diagram i was aware of the baro sensor within the oem ecu.

 

Maybe you don't understand the construction of a pressure sensor. It's sealed as it is. So wether it gets a bit of air on what you think is the backside or not doesn't have a noticable affect.

 

Yes i understand the construction of a map sensor. There is a diaphram within a sealed housing and one side of the diaphram is referancing manifold vacuum/positive pressure and the other side of the diaphram is a fixed pressure of dry air. The reason i beleive other map sensors have different resolution (higher boost pressure) is because the fixed pressure is raised. What my thought process is about the temperature compensation is that the being in the location it is and air temperatures/manifold tempertures that is sees may effect this fixed air pressure creating inaccurate or slight flucuation in mapping using manifold pressure vs. rpm. Although this is just my assumption on the matter that is why i am leaving it for discussion or further explination.

 

What you need is data.

Buy two map sensors, one that does not have this diaphram temp comp. and These "yoparts" ones that do.

Do an endurance race, starting from cold and running say... 20 minutes. THEN plot the data against each other. If one does have differences, then call me a believer! But we can speculate all day which is better. With out data it is irrelevant.

edit: After thinking about this, even that test is flawed. You would need to do this simulating these conditions in a lab with a scientific standard pressure measurement as the benchmark, and then have sensors testing what the developed pressure is. Then you can see which of the two is correct. Regardless, we need tests!

 

That is exactly the first thing that came to mind when I read the first post.

Instead of asking on here and speculating, actually put the sensor to the test.

 

Ok, think about this....

Say you decide to use this YoParts sensor. You install it and run the damn thing. Your intake manifold/throttle body warm up to, let's keep it simple, 100 deg F. Intake air temp is 50 deg F. You think that the heat soak of the manifold/throttle body will affect the "temperature compensation" of the sensor at all? My educated guess is that it will and then you won't get accurate IAT readings which possibly makes it even worse than not having a compensated sensor.

Understand where I am coming from here.

I totally agree though with Sander. A simultaneous test needs to be done. If I was home I could do it no problem at work, but I'm not, so that option is out. lol

 

As i said its not just this paticular sensor with this feature or design within it. Many sensors have this which probably many of the honda/acura community are using. Alot of non automotive pressure sensors have this aswell.

Tepid it has nothing to do with the IAt sensor. Its about keeping a linear and accurate map value based on temperature of the unit. The dry air media behind the diaphram which is sealed can create a pressure change causing pressure differential to change causing the voltage to skew. This would creat inaccurate manifold pressure reading because of the sensors linear rate has changed.

Now i have done some more research and have come up with some gathered information. Alot of sensors and when veiwing datasheets has a temperature operation scale. This scale is within its compensation capabilities otherwise the pressure would drift from a linear rate.

If you simply google "pressure sensor temperature compensation" you can find alot on the matter and certain ways of implementing this ofset or correction. Generally in automtove these corrections scales go farther then we will eveer need. I think this is not new technology withing pressure/vacum sensors automotive use and non automotive use but atleast i understand its place within our sensor.

I don't think any tests are neccissary as i think the answer is now clear.

 

clear as mud?