MAP sensor...has a breather hose?
Thread Starter
Staging Lane
Joined: May 2007
Posts: 95
Likes: 2
MAP sensor...has a breather hose? I bought a vette that used to be set up as an 800hp supercharged vette (top end was stripped and turned into a cammed NA engine), and I'm trying to fix my idling problem,but I dont know for sure how exactly the MAP sensor is supposed to be set up. I found out the MAP had a loose wire and it wouldnt let my engine idle at all...had to hold down the pedal to keep it running. It was just dumping massive amounts of fuel into the engine.
After fixing the broken wire... the idle is very high, almost 2k sometimes but after coming to a stop the idle kicks down to about 900 after a second.
I put my hand behind the intake trying to feel around for hoses connected back there...and i found a small about 1/4" diameter hose about 4 inches long hanging there not connected to anything. I cant seem to find any information that helps me out...can anyone help me understand what hoses need to be connected to the MAP?
After fixing the broken wire... the idle is very high, almost 2k sometimes but after coming to a stop the idle kicks down to about 900 after a second.
I put my hand behind the intake trying to feel around for hoses connected back there...and i found a small about 1/4" diameter hose about 4 inches long hanging there not connected to anything. I cant seem to find any information that helps me out...can anyone help me understand what hoses need to be connected to the MAP?
None. The MAP sensor connects into the intake manifold, that's it. The hose in question may have been used for a boost sensor when it was supercharged. Just plug it. It is causing a vacuum leak that is likely the source of the high idle issue.
11 Second Club
Joined: Nov 2001
Posts: 300
Likes: 1
From: Central Florida
First... if it's leaking, of course, fix the leak.
Second, that hose leading up to the MAP sensor creates a column of air that acts like a buffer zone between the intake and the MAP sensor. It prevents the MAP from being overly sensitive to changes in vacuum/boost pressure in the intake, allowing it to maintain a more steady reading for the PCM. This tends to help with lumpy cams and supercharged applications, particularly when the engine is under high load (such as idling through heavy traffic with the AC running and the cooling fans on at high speed). It's a trick a master technician showed me for my LS6. I was having problems with the engine stalling in traffic w/AC running. Once I fabbed up an extension, that fixed the problem.
-R
Second, that hose leading up to the MAP sensor creates a column of air that acts like a buffer zone between the intake and the MAP sensor. It prevents the MAP from being overly sensitive to changes in vacuum/boost pressure in the intake, allowing it to maintain a more steady reading for the PCM. This tends to help with lumpy cams and supercharged applications, particularly when the engine is under high load (such as idling through heavy traffic with the AC running and the cooling fans on at high speed). It's a trick a master technician showed me for my LS6. I was having problems with the engine stalling in traffic w/AC running. Once I fabbed up an extension, that fixed the problem.
-R
