How many MAP sensors?
Thread Starter
MBWorld Fanatic!
Joined: Feb 2008
Posts: 1,803
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From: Charleston, SC
GL450
How many MAP sensors?
Are there 4 MAP sensors on the V12TT?
I see one on each air box and one T'd off the passenger IC (mounted above the TB). That's 3 total.
Is there a 4th underneath the ICM that meters post-TB?
I see one on each air box and one T'd off the passenger IC (mounted above the TB). That's 3 total.
Is there a 4th underneath the ICM that meters post-TB?
MBWorld Fanatic!
Joined: Nov 2010
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From: Welwyn, Herts, UK
2006 S600
You're right about the locations, but I can't remember if they're ALL MAP sensors. The ones on the IC's might be temp sensors. The important one is on the intake manifold itself, downstream of the throttle, under the ignition amp. You can almost certainly find the right answer from the link in this thread:
https://mbworld.org/forums/m275-v12-...75-freaks.html
https://mbworld.org/forums/m275-v12-...75-freaks.html
Super Member
Joined: May 2015
Posts: 554
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2004 S600
Old thread, I know. But for future searchers I feel like I should update this. There are actually at least 5 air pressure sensors, but only 4 can be independently replaced. One in the intake manifold, one referenced to the passenger intercooler outlet (pre-throttle body), one in each airbox, and #5 is internal to the engine computer as an atmospheric reference. There could be more that I haven't stumbled across yet.
MBWorld Fanatic!
Joined: Aug 2013
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From: Anchorage
05 CL65
After dealing with a boost issue 2-1/2 years ago I found the same results you did. The two in the air boxes only measure vacuum and are different than the one in the manifold and the one attached to the intercooler by a hose. The air box sensors are not interchangeable with the other two.
Super Member
Joined: May 2015
Posts: 554
Likes: 37
2004 S600
After dealing with a boost issue 2-1/2 years ago I found the same results you did. The two in the air boxes only measure vacuum and are different than the one in the manifold and the one attached to the intercooler by a hose. The air box sensors are not interchangeable with the other two.
Also, be careful not to switch the plugs on the passenger side airbox and intercooler outlet map. They will reach and it will run and drive fine at low load, but it will cause very unpleasant results when you give it more than about half throttle.
Last edited by ZephTheChef; Jun 14, 2016 at 08:15 PM.
