Search



Go Back   Third Generation F-Body Message Boards > Tech Boards > Tech / General Engine
Register Forgot Password?

Tech / General Engine Is your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
Sponsored by Weld Racing
Click Here

Welcome to ThirdGen.org!
Welcome to ThirdGen.org.

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, at no cost, 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, join the ThirdGen.org community today!


Reply
 
Thread Tools Search this Thread
Old 07-25-2011, 07:51 AM   #1
Junior Member
 
Join Date: Jun 2009
Posts: 56

Classifieds Rating: (0)
Differential vs Absolute pressure sensor confusion

Hi,
I'm looking to change my MAP sensor and I've already placed my order at rockauto.com
The thing is under MAP they have absolute and differential sensors and I ordered a differential sensor. The more I read and look into it the more confused I get. What is the difference and which one do I need? I'm afraid I've ordered the wrong one and I need quick help, so I can change the order before they ship it.

The car is a 1987 Camaro 305 4bbl (H)

Thanks in advance.
snoopybg is offline vBGarage Page   Reply With Quote
Old 07-28-2011, 08:03 PM   #2
Junior Member
 
IROCyou86's Avatar
 
Join Date: Apr 2010
Location: Sunnyvale, CA
Posts: 35
Car: 1983 Z28
Engine: 305 LG4 soon to be FRANKENSTEIN L69
Transmission: T-5 NWC
Axle/Gears: 3.23

Classifieds Rating: (0)
Re: Differential vs Absolute pressure sensor confusion

I'm confused as to why you need a MAP sensor on a carbureted engine? Maybe you mistook the circle air cleaner to be concealing a carb instead of tbi. '87+up have EFI engines only unless you swapped out.
IROCyou86 is offline vBGarage Page   Reply With Quote
Old 07-29-2011, 02:05 AM   #3
Junior Member
 
Join Date: Jun 2009
Posts: 56

Classifieds Rating: (0)
Re: Differential vs Absolute pressure sensor confusion

There is a MAP and a BARO sensor on the LG4 engine in 1987
snoopybg is offline vBGarage Page   Reply With Quote
Old 07-29-2011, 10:55 PM   #4
Junior Member
 
IROCyou86's Avatar
 
Join Date: Apr 2010
Location: Sunnyvale, CA
Posts: 35
Car: 1983 Z28
Engine: 305 LG4 soon to be FRANKENSTEIN L69
Transmission: T-5 NWC
Axle/Gears: 3.23

Classifieds Rating: (0)
Re: Differential vs Absolute pressure sensor confusion

That hurts my brain. I looked it up and you're completely right about the 2 sensors. Only the "MAP" reacts to vaccum the opposite way EFI cars do, making it a differential pressure sensor instead of an absolute. They're chillin on either sides of the brake booster in the engine bay. I apologize for my starkness, mine are disconnected, out of sight and out of mind; explains a lot.
IROCyou86 is offline vBGarage Page   Reply With Quote
Old 07-30-2011, 06:04 AM   #5
Junior Member
 
Join Date: Jun 2009
Posts: 56

Classifieds Rating: (0)
Re: Differential vs Absolute pressure sensor confusion

Closer to the fender is the MAP and closer to the engine is the BARO? The BARO is supposed to be disconnected. Does it have seafoam glued to the inlet?

I've been searching for several days now and all I get is controversial information from the internet.

I've decided to stick to STM brand to ease my search. For my car they have two MAP/BARO sensors-the AS6 and the AS10. Even their official online catalogue is confusing me and I don't know with 100% certainty which one is the actual MAP sensor I need.
As far as I've deduced from the million different listings I've seen I think the AS6 is the BARO and the AS10 is the MAP. However when I search it by car and year I get AS6 as the MAP...

If someone actually knows, please explain which engines have which of these:

Manifold Absolute Pressure
Manifold Differential Pressure
Baro sensor
Attached Images
File Type: jpg AS6.JPG (111.3 KB, 19 views)
File Type: jpg AS10.JPG (105.8 KB, 12 views)
snoopybg is offline vBGarage Page   Reply With Quote
Old 07-30-2011, 08:30 AM   #6
Supreme Member
 
Join Date: Sep 1999
Location: Philly, PA
Posts: 6,666

Classifieds Rating: (0)

Re: Differential vs Absolute pressure sensor confusion

Carb engiens use a VAC sensor (vacuum from the maifold) and an BARO sensor (open to the air- no hose attached). Speed/density EFI stuff uses a MAP sensor.

I'm guessing that the Pressure Differential Sensor you are referring to is the VAC sensor. They read effectively the reverse of a MAP sensor (i.e. they are not the same as a later model MAP sensor).
Damon is offline vBGarage Page   Reply With Quote
Old 07-30-2011, 10:27 AM   #7
Junior Member
 
Join Date: Jun 2009
Posts: 56

Classifieds Rating: (0)
Re: Differential vs Absolute pressure sensor confusion

I think we solved the mystery.

Carb engines--->(VAC = Manifold Differential Pressure sensor) + Baro sensor
EFI---> MAP sensor = Manifold Absolute Pressure sensor
snoopybg is offline vBGarage Page   Reply With Quote
Old 07-30-2011, 10:27 AM
ThirdGen
1992 Camaro




Paid Advertisement


Reply

Go Back   Third Generation F-Body Message Boards > Tech Boards > Tech / General Engine

Tags
1984, 1991, 86, abslute, absolute, camaro, delta, differential, manifold, map, pressure, sensor, transducers, v, versus, z28
Thread Tools Search this Thread
Search this Thread:

Advanced Search

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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

 


1982 Camaro '82 || 1983 Camaro '83 || 1984 Camaro '84 || 1985 Camaro '85 || 1986 Camaro '86 || 1987 Camaro '87 || 1988 Camaro '88 || 1989 Camaro '89 || 1990 Camaro '90 || 1991 Camaro '91 || 1992 Camaro '92


All times are GMT -5. The time now is 03:04 PM.


Powered by vBulletin® Version 3.7.5
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
All content copyright 1997 - 2014 ThirdGen.org. All rights reserved. No part of this website may be reproduced without the expressed, documented, and written consent of ThirdGen.org's Administrators.

Emails & Contact Details