anybody know what or where this is??
Thread Starter
Junior Member
Joined: Jun 2001
Posts: 50
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From: New Jersey
anybody know what or where this is??
I have an 87 305 camaro and i keep getting code 34 on the ecm which is a differential pressure sensor. what and where is that?
thanks alot
andrew
thanks alot
andrew
Supreme Member
Joined: Sep 1999
Posts: 3,197
Likes: 10
From: Manassas VA
Car: 04 GTO
Engine: LS1
Transmission: M12 T56
The differential pressure sensor is also known as a vacuum(VAC) sensor. On my 85 LG4 it was located on the drivers side firewall with the ESC and EST modules. It is a little black rectangle that will havea 3wire connector coming from the bottom, as well as a hard plastic vacuum line.
To troubleshoot, find the sensor. With the engine running, disconnect the vacuum line and plug it with your finger. You should feel good vacuum. If not, make sure it is connected at the carb, you'll see a hard plastic vacuum line coming off a port at the back of the carb. If that is disconnected, problem solved. If it is connected, pull the line off the carb and make sure their is vacuum at the port, if not then it is dirty, try spraying some carb cleaner in it.
If you have vacuum at teh carb port, but not at the other end of the line, then the line is broken and you need to replace that. Regualr vacuum hose is fine.
If you have vacuum at the sensor, and you don't see a significant change in the way the engine idles when you disconnect teh vacuum line then i would sday teh sensor itself is shot. When you buy a replacement make sure you get a VAC sensor, not a MAP sensor. they are physically identical, but functioanlly they are opposites, and many people do not realize that the CCCS cars used a VAC instead of MAP sensor.
...ed
------------------
Ed Maher - Moderator @ The Carb Board
92 Z28 Convertible - Quasar blue / Tan top
LB9 4L60 GU2 G80 - stock, soon to be sleeper
-=ICON Motorsports=-
- Definitely prototypes, high powered mutants of some kind. Too weird to live, too cool to die
To troubleshoot, find the sensor. With the engine running, disconnect the vacuum line and plug it with your finger. You should feel good vacuum. If not, make sure it is connected at the carb, you'll see a hard plastic vacuum line coming off a port at the back of the carb. If that is disconnected, problem solved. If it is connected, pull the line off the carb and make sure their is vacuum at the port, if not then it is dirty, try spraying some carb cleaner in it.
If you have vacuum at teh carb port, but not at the other end of the line, then the line is broken and you need to replace that. Regualr vacuum hose is fine.
If you have vacuum at the sensor, and you don't see a significant change in the way the engine idles when you disconnect teh vacuum line then i would sday teh sensor itself is shot. When you buy a replacement make sure you get a VAC sensor, not a MAP sensor. they are physically identical, but functioanlly they are opposites, and many people do not realize that the CCCS cars used a VAC instead of MAP sensor.
...ed
------------------
Ed Maher - Moderator @ The Carb Board
92 Z28 Convertible - Quasar blue / Tan top
LB9 4L60 GU2 G80 - stock, soon to be sleeper
-=ICON Motorsports=-
- Definitely prototypes, high powered mutants of some kind. Too weird to live, too cool to die