E30 throttle body question: Grassroots Motorsports forum: Grassroots Motorsports Magazine

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Nov. 10, 2010 10:46 a.m. TJ SuperDork

I am using an E30 325is throttle body on an E30 318i intake manifold as part of my Megasquirt project on the 2002.

Last night I was test fitting together my intake manifold and have a couple questions concerning my throttle body.

I have the IAC valve, MAP sensor, FPR vacuum source, and brake booster vacuum source figured out already. There are other ports on the intake and throttle body that I am planning on blocking off. For example: These two ports used to go to the brake booster and some sort of idle air circuit. I will block these off.

But for what was this port originally used? The one under the barb connection I am using for the IAC. It doesn't appear on the Real OEM throttle body pictures that I've looked at.

Just curious to know what it was originally for. It is after the throttle plate.

My other question is can I tap this hole and fit my IAT sensor there? I was planning on putting the IAT sensor in the intake piping before the throttle body, but can I put it in the throttle body?

Thanks, T.J.
Nov. 10, 2010 12:27 p.m. Giant Purple Snorklewacker SuperDork

TJ wrote:

My other question is can I tap this hole and fit my IAT sensor there? I was planning on putting the IAT sensor in the intake piping before the throttle body, but can I put it in the throttle body?

Thanks, T.J.

You can actually put it in the intake manifold after the throttle body if you want to. That is the factory location on the OBD-I E36. Its underneath at the rear away from the direct airflow.
Nov. 10, 2010 12:34 p.m. belteshazzar SuperDork

pcv iirc
Nov. 10, 2010 3:54 p.m. TJ SuperDork

PCV makes sense. I just couldn't find a drawing that matched my particulat throttle body on RealOEM.com. In the end it doesn't matter what it was for I guess. I figured since E30 is one of the holy trinity of GRM right answers someone would know.

Is there a concern with mounting the IAT sensor in the throttle body just after the throttle plate? Would I get artificially low temperature readings at partial throttle sorta like blowing air from my mouth with pursed lips and it feels cold?
Nov. 10, 2010 4:47 p.m. WilberM3 Reader

with the throttle linkage on the top, looking at the inlet, the 2 small ones on the right both go to vacuum booster but there's lots of variations of those hoses over the years. the one where your barb is i believe is the plate that had the coolant passages and is the crankcase vent from the valve cover that goes under the intake manifold. the big port on the left behind/below your barbed one was for idle air control.
here's a pretty good huge image that shows the stock locations
Nov. 10, 2010 5:41 p.m. TJ SuperDork

In reply to WilberM3:

Perfect - thanks.

Now, where do I want to mount my IAT sensor?