General speed density set up question!

[Spector5]

Well I Hooked up the Speed density cable today. Was just double and triple checking to make sure I put the Bar in a appropriate vaccum source.

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[redyute1]

Wrong placement, you need to tap into the intake manifold for map sensor vacuum, if you leave it where you have it , it will not see vacuum till you get on the throttle as a matter of fact it probably will not even start like that,but i can be wrong. Have you fired it up?

 

[Spector5]

HAHA, as a matter of fact it does start. It just doesn't idle. You just helped me figure our my idle problem.

 

[jpmxrider489]

If you don't feel like tapping, you can t in the fpr.

 

[snowborder714]

Ideally the MAP sensor should have its own dedicated vacuum line, which is as short as possible from the intake manifold. I wouldn't recommend using a throttle body port for this - it should come from the manifold.

 

[Gunner Smith]

I have a question as well. Still a little new to car stuff so may need pictures if possible. I see that you need to tap and weld the bung on but what is the thing in the second picture where should I put it. I am aware one is a IAT and one is a MAP sensor but in the second picture what is that and where should I put it? Thank you.

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Also my speed density is a 3.5 Bar plug and play kit off eBay.

 

[wing3r09]

@Gunner Smith Looks like your map sensor on the left and your MAF connector on the right. MAP uses a vaccum/boost source from the intake manifold. Either use an existing port or drill and tap one. For the MAF you use two of the wires from that harness and connect them to your IAT sensor pigtail. IAT bung is welded onto the intercooler pipe. I have mine close to the throttle body. I can't remember where exactly it should be but a quick search can pull that up.

 

[randman2011]

As close to the throttle body as you can get while still being in smooth flow is what you want for the temp sensor. I have my bung right in the middle of the bend on my 2g pointing almost straight up so the connector comes up between the two throttle cables of the cruise control module. I'd recommend putting yours right before the last bend in your intercooler pipe. In your first picture it looks like you might already have a brass nipple right there.

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My MAP sensor is fed by that red vacuum line behind the manifold. In my application that vacuum port on the right of the manifold serves the MAP for the ECU, a MAP for my boost gauge, and the fuel pressure regulator.

 

[Gunner Smith]

@wing3r09 my speed density is all one piece does that mean I need to cut it up I’ve seen a lot of people say where to Connect the wires but I don’t want to cut mine since it’s a one piece harness. @randman2011 yeah that’s what I was planning on putting my IAT in place of that brass nipple also mine is a 1G so do you know if the vacuum lines will be in the same place

 

[randman2011]

@wing3r09 my speed density is all one piece does that mean I need to cut it up I’ve seen a lot of people say where to Connect the wires but I don’t want to cut mine since it’s a one piece harness. @randman2011 yeah that’s what I was planning on putting my IAT in place of that brass nipple also mine is a 1G so do you know if the vacuum lines will be in the same place

I don't, and my manifold is an Evo 3 so it would be different from the stock 3g as well. I don't know anything about the 1g at all but there should still be a nipple on the right side of the manifold that originally serviced the factory fuel pressure regulator.

Are you using a subharness or have you cut out the factory MAF connector and are running wires straight to the engine harness? ECMLink's harness includes connectors for both MAP and IAT, for example. This is what I use. And I know their harness has the MAP sensor input on the Baro line, which caught me off guard when I was setting up my ECU. Maybe ECMLink is expecting that, but I'm running Megasquirt.

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[1990TSIAWDTALON]

While you might HAVE to use the only vacuum/boost source that you have (which may be the fuel pressure regulator lined), I don't recommend it in that place. In the slight chance that the hose comes off, you will run lean from no source to the fuel regulator. On my 1g stock manifold, I run my AEM 4 Bar off of the "P" port on the TB. Tuners will also tell you to never tie into the fuel pressure line for anything and make you move it to another source. Just putting that out there.
Marty

 

[Dericsh]

Here’s a jafro video showing his speed density setup

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[Gunner Smith]

I bought this. I also am running a dsm link ecu.

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[Gunner Smith]

@1990TSIAWDTALON can I plug it into my oil catch can my oil catch can was already plugged into my maf

 

[1990TSIAWDTALON]

That would be a NO. The catch can is an open line, no one way valve or anything. Your MAF shouldn't be tee'd into it either. What ports are available on the throttle body and the intake manifold?

 

[Dericsh]

correct me if I’m wrong, is he having a hard time finding a connection point bc he got the mitsu style map sensor that is more for 2g manifolds and should be using a gm style so he can use a smaller vacuum port/line?

 

[1990TSIAWDTALON]

Deric, I believe so.
@Gunner Smith , the Manifold Absolute Pressure sensor you have is indeed meant to screw into a port like a 2g motor uses. You really need a GM style MAP sensor. It uses a small vacuum line like you BOV or AFPR uses and mounts to the firewall or any other convenient location.
This is the type of MAP sensor that a lot of 1g owners, including myself, use.

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[Gunner Smith]

@1990TSIAWDTALON and @Dericsh my buddy is telling me that map sensor needs to be plugged into my intake pipe would that be something, maybe. if not I’ll take your route and just buy that map sensor just trying not to spend any more money than I already have.

 

[1990TSIAWDTALON]

You buddy may be referring to the AIT (Air Intake Temperature) sensor, which is used in conjunction with the MAP sensor for Speed Density. It will go in the intake tract of the car. I mount mine in the TB elbow, about 3-4" away from the TB.
In your picture, it is the sensor that is gold with a grey electrical connection on it and orange thread sealer on it. You weld the round bung into the intake tract (intercooler piping) then screw that sensor in and connect and configure it.

 

[Gunner Smith]

No I think he understands that because he even told me he doesn’t want to weld the bung because it’s made of aluminum and he’s scared it’s going to set on fire when he stick Welds it.

 

[Dericsh]

No I think he understands that because he even told me he doesn’t want to weld the bung because it’s made of aluminum and he’s scared it’s going to set on fire when he stick Welds it.

I know you don’t want to spend more money, but It’s important that you set this up properly or you may as well go back to a MAF setup. If you don’t have the means to have the bung welded into the elbow, you can purchase a throttle body elbow with a bung pre installed from archer fab or stm tuned.

 

[1990TSIAWDTALON]

Well to be clear, to run Speed Density, the AIT bung will need to be installed and the AIT configured and hooked up along with the MAP sensor.

 

[Gunner Smith]

OK that is understandable I will have the bung weld on And purchased a new piece I can’t go back to maf because that is my problem right now is for some reason whenever I’m hooked up to the maf the car idols at 500 RPMs not even 1000 I took it apart and it doesn’t even look dirty so my friend suggested speed density

 

[1990TSIAWDTALON]

Gunner, this is the MAP sensor we are talking about when we speak of a GM style sensor. This on is on my personal car. It is a 4 bar sensor.

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[Gunner Smith]

OK that is understandable I will have the bung weld on And purchased a new piece I can’t go back to maf because that is my problem right now is for some reason whenever I’m hooked up to the maf the car idols at 500 RPMs not even 1000 I took it apart and it doesn’t even look dirty so my friend suggested sd