Manifold Differential Pressure Switch

[AllBoostNoJuice]

I recently ran a scanner on my car, and found that I had a p1400. (Manifold Differential Pressure Switch) However, this code never turned on the CEL, therefore I just ignorfed it. My question is, what does this sensor do, and how is my car being effected by having a bad one?

Thanks

 

[eclpsegsx12]

Isnt that the MAP sensor??? i have that code too...its either that or something to do with emmisions

 

[1LE]

It's often called the MAP sensor. It's part of the way that the 2g ECU checks to see if your EGR is working.

 

[Strm Trpr]

I think it has something to do with vacuum/boost differential in the manifold...
If you pulled a code, probably on it's way out, they are expensive from , but I'd recommend replacing it, cuz when mine thru a CEL, my car would buck like crazy, like I had a huge boost leak....

 

[Coldandafraid]

MAP on a non-turbo. MDP on a turbo.

You could be getting the code because the sensor is dirty, or the egr is clogged/blocked.

 

[Strm Trpr]

MAP on a non-turbo. MDP on a turbo.

You could be getting the code because the sensor is dirty, or the egr is clogged/blocked.

You're so right, I've seen MAP misused in this forum a few times....
I too have heard of people cleaning their MDPS's and their CEL never came back on.... well at least w/out that same code.... he he he....

 

[AllBoostNoJuice]

I will try cleaning it today. I know that it isn't the EGR b/c I just replaced it. Thanks.

 

[1LE]

Could someone please tell me where it comes out of the wiring harness (and what color wires are on it)? I *may* have a problem with mine, but I've got a 1g intake manifold and hence it's NOT where it's supposed to be! All my electrical is 2g, so I'm hoping to find the MDP by finding out where it splits off the harness, and then following that down.

 

[Strm Trpr]

Could someone please tell me where it comes out of the wiring harness (and what color wires are on it)? I *may* have a problem with mine, but I've got a 1g intake manifold and hence it's NOT where it's supposed to be! All my electrical is 2g, so I'm hoping to find the MDP by finding out where it splits off the harness, and then following that down.

This is what it looks like, sorry I'm not sure what color the wires are, but
I do know that it attaches to the intake manifold on the intake plenum....
Here's a link to a previous photo.....
http://www.dsmtuners.com/forums/showthread.php?t=135556
Scroll down to post #11 and you'll see the pick.....

 

[1LE]

This is what it looks like, sorry I'm not sure what color the wires are, but
I do know that it attaches to the intake manifold on the intake plenum....
Here's a link to a previous photo.....
http://www.dsmtuners.com/forums/showthread.php?t=135556
Scroll down to post #11 and you'll see the pick.....

Thanks! I found it... There's a "T" on a hose coming out the front (of the car) side of the intake manifold. One side of the "T" goes passenger side a couple inches, and into the MDP. The other side of the "T" goes all the way around past the FPR, back to the firewall, to a square looking "box" with only the one vacuum line going in, and an electrical connector. Anyone know what THAT is??? Wonder if a malfunction in "whatever that is" can also cause EGR MILs?

 

[Strm Trpr]

Thanks! I found it... There's a "T" on a hose coming out the front (of the car) side of the intake manifold. One side of the "T" goes passenger side a couple inches, and into the MDP. The other side of the "T" goes all the way around past the FPR, back to the firewall, to a square looking "box" with only the one vacuum line going in, and an electrical connector. Anyone know what THAT is??? Wonder if a malfunction in "whatever that is" can also cause EGR MILs?

Man, I'm only familiar with the 2g's set-up, but it sounds like there's a boost
gauge tapped into the MDP..... Do you have an aftermarket boost gauge set-up?

 

[1LE]

This *is* a 2g... Electrically, anyways

Duh, Imadoofus. That's the pressure sensor for my VPC... Sheesh. I'm losin' it here I just now replaced the short piece of hose from the manifold to the "T" (since I had extra anyways). Was *going* to replace the section of hose to the MDP in case it was clogged, BUT, it doesn't seem like the hose will come off of there. Is the vacuum hose part of the MDP?

 

[Coldandafraid]

no. The MDP is just a nipple on the end. I assume you have a vac line attached to your MDP because your intake mani is from a 1G...

 

[1LE]

Ah, OK. Well, they're cheap enough that I think I'm just gonna go ahead and order a new MDP so I'll be able to mess around with trying to get a new vacuum hose on it without taking my car out of service while I try and figure it out...

 

[Coldandafraid]

cheap!? the dealer here wants $240 canadian for one...

 

[1LE]

$90 US. If it was for my MR2 it'd probly be $300+ US... Of course, if it was for a Mustang it'd be about $8. All a matter of perspective