MAP Sensor Location
Thread Starter
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Senior User
Joined: Sep 2000
Posts: 162
Likes: 0
From: Castine, ME
MAP Sensor Location
hello,
I need to replace the MAP sensor on my truck, bu have been unable to find it. My Hanes manual says to find it on the firewall near the evaporator housing. It is not there, however. If anyone has any ideas it would be much appreciated.
thanks,
I need to replace the MAP sensor on my truck, bu have been unable to find it. My Hanes manual says to find it on the firewall near the evaporator housing. It is not there, however. If anyone has any ideas it would be much appreciated.
thanks,
Lead Driver
Joined: Nov 2002
Posts: 9,555
Likes: 40
From: Concord, NC
How do you know it is bad? It's on the firewall with a vacuum line going to it. It could be MAF, in which case, there would be no vacuum line going to it. The only place I know them to be is right where you are looking. It has 3 wires going to it, and as you are looking at the engine, it is just to the left above the intake manifold at the very top of the firewall.
Thread Starter
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Senior User
Joined: Sep 2000
Posts: 162
Likes: 0
From: Castine, ME
ha....yea, I never thought about that, it is MAF, I was just acting on some advice. Oh, well, thanks for the reply. The problem I am trying to diagnose is as follows: (I have posted this separately in the small block forum.)
At random points while driving (most apparent at highway speeds), the truck experiences random "spells" of power loss. It feels like a roughly 20-25hp loss and results in excessive downshifting out of overdrive on highway hills as well as a loss of throttle response. There are no codes and the truck runs fine; idles smooth as glass, starts quickly, smooth accelleration with no apparent flat spots.
Parts replaced:
-O2 sensor
-throttle position sensor
-plugs, cap and rotor
-disconected EGR valve (at electrical connection) to see if this may be the problem, no change.
-fuel pressure regulator
I have not changed the fuel filter, however, if the symptoms are random, I seem to think this would not be the cause. My current thoughts are a timing/mixture control issue. I thought to replace the MAP sensor, however my truck is MAF, so as far as I know, one does not exist.
Thanks
At random points while driving (most apparent at highway speeds), the truck experiences random "spells" of power loss. It feels like a roughly 20-25hp loss and results in excessive downshifting out of overdrive on highway hills as well as a loss of throttle response. There are no codes and the truck runs fine; idles smooth as glass, starts quickly, smooth accelleration with no apparent flat spots.
Parts replaced:
-O2 sensor
-throttle position sensor
-plugs, cap and rotor
-disconected EGR valve (at electrical connection) to see if this may be the problem, no change.
-fuel pressure regulator
I have not changed the fuel filter, however, if the symptoms are random, I seem to think this would not be the cause. My current thoughts are a timing/mixture control issue. I thought to replace the MAP sensor, however my truck is MAF, so as far as I know, one does not exist.
Thanks
Lead Driver
Joined: Nov 2002
Posts: 9,555
Likes: 40
From: Concord, NC
Try cleaning the wires in the MAF sensor with a q-tip and some rubbing alcohol. The wires in the sensor can get dirty and give a false air mass reading and thus throw things off with the computer.
