Welcome to the North American Subaru Impreza Owners Club Thursday January 29, 2015
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
Mid Atlantic Impreza Club
Mid Atlantic Impreza Club Forum sponsored by Annapolis Subaru
Here you can view your subscribed threads, work with private messages and edit your profile and preferences Home Registration is free! Visit the NASIOC Store NASIOC Rules Search Find other members Frequently Asked Questions Calendar Archive NASIOC Upgrade Garage Logout
Go Back   NASIOC > NASIOC Chapters > Mid Atlantic Impreza Club -- MAIC

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads.
Reply
 
Thread Tools Display Modes
Old 12-19-2012, 10:42 PM   #4026
isis
Scooby Specialist
 
Member#: 73283
Join Date: Oct 2004
Chapter/Region: MAIC
Location: Pittsburgh, PA
Vehicle:
05 CTS-V
03 Z1000

Default

**** engineering is the most solid agreement I've had with you in a while. I cherish these moments.
* Registered users of the site do not see these ads.
isis is offline   Reply With Quote
Old 12-20-2012, 12:00 PM   #4027
Moore Performance
NASIOC Vendor
 
Member#: 231489
Join Date: Dec 2009
Chapter/Region: MAIC
Location: Pittsburgh, Pa
Default

Quote:
Originally Posted by MRF582 View Post
^LOL nice! **** engineering. I should've gotten into mergers and acquisitions... Which reminds me, I have some videotapes to return.
I agree. thats why i just acquired a dual boost domain name
Moore Performance is offline   Reply With Quote
Old 12-20-2012, 02:58 PM   #4028
glhs377
Scooby Specialist
 
Member#: 125388
Join Date: Sep 2006
Chapter/Region: Tri-State
Location: iron city
Vehicle:
97 240hp NA GF6
giant Carbotron wing

Default

finally some goddamned justice!
http://www.cnn.com/2012/12/18/world/...ist/index.html

inspector gadget level crooks!
glhs377 is offline   Reply With Quote
Old 12-20-2012, 05:09 PM   #4029
MRF582
Scooby Guru
 
Member#: 48219
Join Date: Nov 2003
Chapter/Region: MAIC
Location: Pittsburgh, PA
Vehicle:
. Always drive
the race line .

Default

Jesse, question about a 4 wire MAF with pins for:
12v+
Ground
5v Signal
5v Signal Return

WTH is '5v signal return'? Is that the same thing as 'signal ground' or 'sensor ground'? If so, then why is it a separate pin from the other the ground?

Last edited by MRF582; 12-20-2012 at 05:19 PM.
MRF582 is offline   Reply With Quote
Old 12-20-2012, 05:45 PM   #4030
stealthx32
Scooby Specialist
 
Member#: 30990
Join Date: Dec 2002
Chapter/Region: MAIC
Vehicle:
'93 FD3S

Default

Sensor grounds are pretty common to isolate from the noise your mom kept making last night.
stealthx32 is offline   Reply With Quote
Old 12-20-2012, 05:50 PM   #4031
isis
Scooby Specialist
 
Member#: 73283
Join Date: Oct 2004
Chapter/Region: MAIC
Location: Pittsburgh, PA
Vehicle:
05 CTS-V
03 Z1000

Default

Quote:
Originally Posted by MRF582 View Post
Jesse, question about a 4 wire MAF with pins for:
12v+
Ground
5v Signal
5v Signal Return

WTH is '5v signal return'? Is that the same thing as 'signal ground' or 'sensor ground'? If so, then why is it a separate pin from the other the ground?
Signal ground, yes. It's probably not tied to actual ground until it hits the ECU. Keeps noise off the line from the computer's perspective, and is easier to filter since its isolated from the power grounds. You can prob verify that they are connected on the ECU connector. The ground at the sensor is for the +5v supply. If you tied them at the sensor, you would probably see voltage offsets depending on signal voltage and wire temperatures and whatnot.

There's also a chance that its a differential signal and not tied to ground at all. Voltage can be measured between two nodes anywhere in a circuit and not just referenced to ground. Think of it like relative pressure vs absolute pressure.
isis is offline   Reply With Quote
Old 12-20-2012, 09:33 PM   #4032
MRF582
Scooby Guru
 
Member#: 48219
Join Date: Nov 2003
Chapter/Region: MAIC
Location: Pittsburgh, PA
Vehicle:
. Always drive
the race line .

Default

Quote:
Originally Posted by stealthx32 View Post
Sensor grounds are pretty common to isolate from the noise your mom kept making last night.
Quote:
Originally Posted by isis View Post
Signal ground, yes. It's probably not tied to actual ground until it hits the ECU. Keeps noise off the line from the computer's perspective, and is easier to filter since its isolated from the power grounds. You can prob verify that they are connected on the ECU connector. The ground at the sensor is for the +5v supply. If you tied them at the sensor, you would probably see voltage offsets depending on signal voltage and wire temperatures and whatnot.

There's also a chance that its a differential signal and not tied to ground at all. Voltage can be measured between two nodes anywhere in a circuit and not just referenced to ground. Think of it like relative pressure vs absolute pressure.
Thank you! Glad to know I wasn't crazy in thinking that. So then can anyone explain this?
http://forums.bimmerforums.com/forum....php?t=1331628
Cuz the BMW folks can't...

And yeah, I fully understand that measured voltage is really just a difference in voltage between two nodes.
MRF582 is offline   Reply With Quote
Old 12-21-2012, 10:35 AM   #4033
MRF582
Scooby Guru
 
Member#: 48219
Join Date: Nov 2003
Chapter/Region: MAIC
Location: Pittsburgh, PA
Vehicle:
. Always drive
the race line .

Default

Don't let nature down, go out and punch someone!
http://news.discovery.com/human/huma...ng-121219.html
MRF582 is offline   Reply With Quote
Old 12-21-2012, 11:40 AM   #4034
isis
Scooby Specialist
 
Member#: 73283
Join Date: Oct 2004
Chapter/Region: MAIC
Location: Pittsburgh, PA
Vehicle:
05 CTS-V
03 Z1000

Default

Quote:
Originally Posted by MRF582 View Post

Thank you! Glad to know I wasn't crazy in thinking that. So then can anyone explain this?
http://forums.bimmerforums.com/forum....php?t=1331628
Cuz the BMW folks can't...

And yeah, I fully understand that measured voltage is really just a difference in voltage between two nodes.
Not sure what's left to explain?
isis is offline   Reply With Quote
Old 12-21-2012, 04:21 PM   #4035
MRF582
Scooby Guru
 
Member#: 48219
Join Date: Nov 2003
Chapter/Region: MAIC
Location: Pittsburgh, PA
Vehicle:
. Always drive
the race line .

Default

Quote:
Originally Posted by isis View Post
Not sure what's left to explain?
Did you read that link? They're saying, the car doesn't run right until you bridge those two together in the harness... It's my understanding that it's better to keep signal ground separate from regular ground till the ECU has a chance to reference against it to keep the noise away. So grounding the two in the harness is counter-productive isn't it?
MRF582 is offline   Reply With Quote
Old 12-21-2012, 05:33 PM   #4036
isis
Scooby Specialist
 
Member#: 73283
Join Date: Oct 2004
Chapter/Region: MAIC
Location: Pittsburgh, PA
Vehicle:
05 CTS-V
03 Z1000

Default

Quote:
Originally Posted by MRF582 View Post
Did you read that link? They're saying, the car doesn't run right until you bridge those two together in the harness... It's my understanding that it's better to keep signal ground separate from regular ground till the ECU has a chance to reference against it to keep the noise away. So grounding the two in the harness is counter-productive isn't it?
Not always. There are 3 ways to hook up a 4-wire sensor. Ground them together at the ecu, ground them together at the sensor or don't ground them together at all. Each method has an impact on the sensor design and ecu design. Unless I'm misunderstanding the problem, you take part a from car a and replace part b on car b so you need to modify the wiring which connects part a to car b. unless part a is identical to part b or car a is identical to car b, it should be expected.

Maybe you're under the impression that one of the methods of hookup is clearly superior? I'm not sure that's the case though.

The BMW is expecting those pins to be connected at the sensor because that's how it was stock. So when you use a sensor that doesn't have them connected, you have to do it in the wiring harness. If you're asking why Porsche and BMW use different sensors, I think you'd need to ask each engineering group. I don't thing there's a good reason either way. It's probably determined by the ecu they pick.

Last edited by isis; 12-21-2012 at 05:40 PM.
isis is offline   Reply With Quote
Old 12-21-2012, 05:41 PM   #4037
glhs377
Scooby Specialist
 
Member#: 125388
Join Date: Sep 2006
Chapter/Region: Tri-State
Location: iron city
Vehicle:
97 240hp NA GF6
giant Carbotron wing

Default

MAF is in the greater scheme of sensors, a really low frequency and low precision device, and has a a pretty lame DAC step anyway you look at it, so advanced or optimal signal path techniques are wasting your time. I'm glad Jesse answered you thoroughly cause i wasn't gonna be polite with my condescension..

DACSTEP, WAIT FOR THE DROP!
glhs377 is offline   Reply With Quote
Old 12-21-2012, 06:48 PM   #4038
glhs377
Scooby Specialist
 
Member#: 125388
Join Date: Sep 2006
Chapter/Region: Tri-State
Location: iron city
Vehicle:
97 240hp NA GF6
giant Carbotron wing

Default

also, MAF is for bustas!
glhs377 is offline   Reply With Quote
Old 12-22-2012, 01:15 AM   #4039
MRF582
Scooby Guru
 
Member#: 48219
Join Date: Nov 2003
Chapter/Region: MAIC
Location: Pittsburgh, PA
Vehicle:
. Always drive
the race line .

Default

Quote:
Originally Posted by isis View Post
Not always. There are 3 ways to hook up a 4-wire sensor. Ground them together at the ecu, ground them together at the sensor or don't ground them together at all. Each method has an impact on the sensor design and ecu design. Unless I'm misunderstanding the problem, you take part a from car a and replace part b on car b so you need to modify the wiring which connects part a to car b. unless part a is identical to part b or car a is identical to car b, it should be expected.

Maybe you're under the impression that one of the methods of hookup is clearly superior? I'm not sure that's the case though.

The BMW is expecting those pins to be connected at the sensor because that's how it was stock. So when you use a sensor that doesn't have them connected, you have to do it in the wiring harness. If you're asking why Porsche and BMW use different sensors, I think you'd need to ask each engineering group. I don't thing there's a good reason either way. It's probably determined by the ecu they pick.
Quote:
Originally Posted by isis View Post
Signal ground, yes. It's probably not tied to actual ground until it hits the ECU. Keeps noise off the line from the computer's perspective, and is easier to filter since its isolated from the power grounds. You can prob verify that they are connected on the ECU connector. The ground at the sensor is for the +5v supply. If you tied them at the sensor, you would probably see voltage offsets depending on signal voltage and wire temperatures and whatnot.

There's also a chance that its a differential signal and not tied to ground at all. Voltage can be measured between two nodes anywhere in a circuit and not just referenced to ground. Think of it like relative pressure vs absolute pressure.
Yeah, I was under that impression because of your comment about the noise being easier to filter out etc. So then follow up question, if one's going to connect power ground and sensor ground at the sensor, why bother with two separate pins, why not just have one ground pin coming out and make it a 3 wire?

What I really need to do is measure the resistance between the two grounds in the harness. If they are shorted, then it doesn't matter.

Quote:
Originally Posted by glhs377 View Post
MAF is in the greater scheme of sensors, a really low frequency and low precision device, and has a a pretty lame DAC step anyway you look at it, so advanced or optimal signal path techniques are wasting your time. I'm glad Jesse answered you thoroughly cause i wasn't gonna be polite with my condescension..

DACSTEP, WAIT FOR THE DROP!
That ECU can read the MAF in increments of 0.0048828125 volts... I wouldn't call that a lame DAC step. In fact, the MAF scaling is 256 cells long. So there's a lookup table datapoint every 0.019volts or so. If you're wondering how I got to these numbers, it's a 10bit DAC. 1024 steps.
MRF582 is offline   Reply With Quote
Old 12-22-2012, 01:39 AM   #4040
isis
Scooby Specialist
 
Member#: 73283
Join Date: Oct 2004
Chapter/Region: MAIC
Location: Pittsburgh, PA
Vehicle:
05 CTS-V
03 Z1000

Default

Quote:
Originally Posted by MRF582 View Post

1 Yeah, I was under that impression because of your comment about the noise being easier to filter out etc. 2 So then follow up question, if one's going to connect power ground and sensor ground at the sensor, why bother with two separate pins, why not just have one ground pin coming out and make it a 3 wire?

3 What I really need to do is measure the resistance between the two grounds in the harness. If they are shorted, then it doesn't matter.
1 I only really explained one hookup I guess. All 3 have different ways of dealing with the problems. Some hardware, some firmware. The reasons I gave were why it would be that one way. There are other reasons to do it another way. I just didn't understand which part you were unclear about.

2 Don't know why. Unless a 4 pin is just standard or more common or something.

3 Probably be all u need. Measure the harness, the ecu and the sensor to get the whole story I guess.
isis is offline   Reply With Quote
Old 12-22-2012, 09:17 AM   #4041
Blinden
Scooby Specialist
 
Member#: 122993
Join Date: Aug 2006
Chapter/Region: MAIC
Location: West PA
Vehicle:
2012 WRX
WRB 5-door

Default

anyone have a set of cheap wheels, I need some winter wheels for the forester, but not really looking to spend a great deal of money.

just looking for somethign 16", 5x100. Not really interested in anything 17 inch unless it's dirt cheap.
Blinden is offline   Reply With Quote
Old 12-22-2012, 11:40 AM   #4042
isis
Scooby Specialist
 
Member#: 73283
Join Date: Oct 2004
Chapter/Region: MAIC
Location: Pittsburgh, PA
Vehicle:
05 CTS-V
03 Z1000

Default

Your mom's dirt cheap.
isis is offline   Reply With Quote
Old 12-23-2012, 02:17 AM   #4043
glhs377
Scooby Specialist
 
Member#: 125388
Join Date: Sep 2006
Chapter/Region: Tri-State
Location: iron city
Vehicle:
97 240hp NA GF6
giant Carbotron wing

Default

shek, 10bit dac aint too bad. i mean.. like it matters. engines will run with.. pretty much anything thrown at them. reference rochester injection, CIS and pretty much anything pre-obd2. i just wanted to say DACSTEP! and maybe bust dan out of hiding.
glhs377 is offline   Reply With Quote
Old 12-23-2012, 02:37 PM   #4044
MRF582
Scooby Guru
 
Member#: 48219
Join Date: Nov 2003
Chapter/Region: MAIC
Location: Pittsburgh, PA
Vehicle:
. Always drive
the race line .

Default

MRF582 is offline   Reply With Quote
Old 12-25-2012, 10:31 AM   #4045
ruby-ru
Scooby Specialist
 
Member#: 44535
Join Date: Oct 2003
Chapter/Region: MAIC
Location: Slippery Rock, PA
Vehicle:
2003 PSM WRX
Twinscroll Goodness!

Default

Merry Christmas!
ruby-ru is offline   Reply With Quote
Old 12-25-2012, 01:33 PM   #4046
MRF582
Scooby Guru
 
Member#: 48219
Join Date: Nov 2003
Chapter/Region: MAIC
Location: Pittsburgh, PA
Vehicle:
. Always drive
the race line .

Default

Quote:
Originally Posted by ruby-ru View Post
Merry Christmas!
Like!
MRF582 is offline   Reply With Quote
Old 12-26-2012, 10:33 PM   #4047
slowgenius
Scooby Specialist
 
Member#: 48350
Join Date: Nov 2003
Chapter/Region: MAIC
Location: Pittsburgh
Vehicle:
0304 0712 WRX/Sti

Default

Whos been out in the snow?
slowgenius is offline   Reply With Quote
Old 12-26-2012, 10:35 PM   #4048
Tentonted
Scooby Newbie
 
Member#: 303864
Join Date: Dec 2011
Vehicle:
2008 Impreza 2.5i 5d
DGM

Default

Quote:
Originally Posted by slowgenius View Post
Whos been out in the snow?
Been out this afternoon, first real snow in my subie, pretty impressed even with summer z rated tires, which are off as of tomorrow, lol.
Tentonted is offline   Reply With Quote
Old 12-27-2012, 01:19 AM   #4049
glhs377
Scooby Specialist
 
Member#: 125388
Join Date: Sep 2006
Chapter/Region: Tri-State
Location: iron city
Vehicle:
97 240hp NA GF6
giant Carbotron wing

Default

i got the CRV to do donuts infront of my shop?

took a few tries though.
glhs377 is offline   Reply With Quote
Old 12-27-2012, 10:03 AM   #4050
isis
Scooby Specialist
 
Member#: 73283
Join Date: Oct 2004
Chapter/Region: MAIC
Location: Pittsburgh, PA
Vehicle:
05 CTS-V
03 Z1000

Default

I've been parked. I'm fairly certain it can do donuts tho.
isis is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Official Pittsburgh Thread Build 4 WastingTime Mid Atlantic Impreza Club -- MAIC 8 04-26-2011 07:58 PM
Official Pittsburgh Thread v5 MRF582 Mid Atlantic Impreza Club -- MAIC 10302 10-07-2010 11:03 AM
Official Pittsburgh Thread V4 Kjott21 Mid Atlantic Impreza Club -- MAIC 10940 10-29-2009 04:16 PM
Official Pittsburgh thread V3.0 MikeCee Mid Atlantic Impreza Club -- MAIC 10519 01-11-2009 10:08 PM
Didn't there used to be an official Pittsburgh Thread? crystalhelix Mid Atlantic Impreza Club -- MAIC 0 01-08-2004 08:23 PM


All times are GMT -4. The time now is 06:54 AM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2015, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2015 Axivo Inc.
Copyright ©1999 - 2014, North American Subaru Impreza Owners Club, Inc.