Forcefed86

iTrader: (4)

What is everyone using here? It says the offsets are supposed to be 33 and 333? Yet when I enter these values and check them against my calibrated MAP sensor ( PLX boost gauge). The results aren’t even close. Using shop air and a regulator I just couldn’t get this sensor to read correctly throughout the range. I run around 20-25lbs of boost mostly so form 15-25lbs Using -30 and 357 was pretty spot on and only a pound or so off at lower boost ranges. I don’t have a way to check the vacuum, but I assume it isn’t pretty. Whats the deal with these sensors? Did GM just tune around their crappyness? Or am I missing something?

Sleeperls

Never thought to bench test the map sensors. Along for the info if you get any.

stevieturbo

Absolutely ALWAYS such test sensors ! It's a first basic setup step when installing or changing such things.

And 3.3bar sensor is mentioned here and GM ?

GM never made a 3.3 bar sensor I am aware of ? And is it an actual OEM GM part you're using ?

Forcefed86

iTrader: (4)

Yup GM part. I went with it because it snapped right into the truck intake for a quick easy install.

AC Delco P/N 213-4658, GM P/N 12623671 formerly GM P/N 12215049 and 16235939. 3.3 BAR sensor

Old PN data sheet

http://www.powerandsignal.com/docs/P...s/12215049.pdf

Link to new part

http://www.gmpartsdirect.com/oe-gm/12623671


Been running one on my RX7 for a while now, but it was always off a bit. (i just tuned around it)

Grabbed another for the mustang I’m putting together and wanted to get it “right”. Or at least as close as possible. It’s almost like it isn’t linear.

I had a vendor selling a knock off of it tell me this.

Scalar: 617
Offset: 11


But I’m not sure how that translates into the MS3 parameters. I believe that’s for factory ECU inputs.

stevieturbo

At the end of the day, as long as it is consistent, that is what matters.

You will calibrate your setup to suit. That's how it works for any sensor. Dont assume, dont use others numbers etc etc.

Nathaninwa

For megasquirt wouldn't zero be zero and 3.3 bar be like the 101.5 x 3.3?

My Omni 4 bar is 0 and 410 iirc to get it reading correct

stevieturbo

Simple answer is test it and see.

Although worth noting that calibrating at 0v and 5v is often silly, as a lot of pressure sensors will never actually ever get to 0v or 5v.

Most will flatline a little before either end ( some a lot, quite a few will only read between 0.5v and 4.5v ) ), so you'd need to plot the line of voltage vs pressure and from that find the hypothetical 0v and 5v readings.

Nitroused383

iTrader: (10)

I think that's the duramax sensor right? It doesn't read accurately at all in vacuum.

stevieturbo

Are you saying it does not give consistent readings ?

Accuracy only depends on what you are calibrating or comparing it to.

if you've calibrated it correctly....then it can only be accurate, unless the sensor itself does not behave in a consistent and repeatable manner.

pdxmotorhead

I've been eyeballing this one,,
http://www.delphi.com/manufacturers/...oline/map-mat/

Its kinda cool, since its both a MAP and a IAT and SMALL.

stevieturbo

Again as long as you can calibrate your system to use it, shouldnt be a problem

and as the post also indicates, they're only showing a linear voltage between 0.5v and 4.5v

So for any system asking for 0v and 5v scalings...you'd need to create hypothetical scalings for this. It's a silly fixed range to be asking for when so many sensors do not read to the voltage extremes.

Nathaninwa

A quick google search shows map sensors being scaled from 0 to 5v. But I agree, motor pressure sensors are scaled in .5-4.5 range and megasquirts gerneric sensor table uses 0-5, there is a formula for figuring the data, I'm logging 100 and 300psi sensors

stevieturbo

Yes, but most will offer more than those 2 points, using only 0v and 5v is just silly because the sensors rarely go that far.

Either way...when it is critical always test, never assume.

Nitroused383

iTrader: (10)

According to these post the duramax 3.3 bar map won't read below 40 kpa

https://ls1tech.com/forums/forced-in...ap-sensor.html

https://ls1tech.com/forums/forced-in...ap-sensor.html

stevieturbo

Not really a huge issue in most cases.

Although a stock engine might idle close to that. Only other times it'd be as low are on the overrun.

But again....dont take others word, test and calibrate the sensor to be sure.