searched throttle body, throttle diagram, mikuni diagram, intake manifold, even googled.
WHAT is the item that is located on the throttle body directly below the TPS?
it has one screw holding it in place/on, you take it off, and it is a flat coil spring wrapped around a plastic shaft, with a little paddle type valve. Does it have something to do with the coolant lines going to the throttle body? it seems so, but what?

 

pretty sure its you idle air control valve

 

see it here?

 

Naah, I think the Idle air control valve is the one with the wire plug, three screws, and directly under throttle inlet. if removed, it is a kind of tapered seal against a hole.

Check it;
This thread:
https://www.evolutionm.net/forums/ev...-canister.html
Picture six:
TPS on the bottom; three screws hold it in.
Directly above that (picture orientation) is the mystery part. Directly to the right is the idle air valve.
And then up above is the EGR valve.
it has a coolant hose entering the throttle body right near it, so.....
Cold weather choke??

 

BuchnerJ,
Thanks for the pic, but it is not listed!
the location is directly under #1, throttle position sensor, same side.

 

Without a picture this thread is useless. The only parts under the TPS are the coolant nipple and ISCV.

 

Where do you see it? Circle it and im sure we can figure it out.

 

Sounds like he's talking about the round disc like part with the phillips head screw in it, attached near the hard line on the middle right side.

 

CORRECT!
I'm at a company computer and prohibited from photobucket and the like, so I can't post a pic.
Yes, the cam shaped cover with the single phillips head screw holding it in.

 

Not true. Early Evo's, 03's and 04's had this little do-hicky in them, the 05's did not. Mikuni made a change to the TB's in 05 and eliminate this thing. If you look at a 03-04's TB it has it, the 05's don't, but still have all the casting marks from the area ready to be machined, but it was never put into them. I know this because I bought a TB from an 03 and it had it, but my 05 did not. I wondered what it was, but eventually decided to keep my 05's TB because it DIDN'T have this part in it. I just modified my 05's instead and put it back on, and eventually sold the 03's. My friends 04 has the same thing on it. Never have seen an 05 or up that has it.

I also never studied it to figure out exactly what it did, but I can imagine it is probably something having to do with the coolant passageways running through the TB because of the location of where it is. It might be a thermostat of some sort due to the spring, or a flow control valve of some sort.

 

To the OP why are you asking about this? Is there a problem with your TB or are you simply curious?

 

I think your refering to a 03/04 tb, which has this additional flapper valve that is controlled by temperature....imo, this was an attempt to get around a bad designed iac. they did away with the flapper for '05.



did yours fall out or did the flapper get melted by meth or?

 

Aby@MIL.SPEC, That's the mystery part I was wondering about. Thanks for the image.



I was curious. I replaced the throttle shaft seals and while I was there, went to clean all the nasty soot and grime the EGR let build up. I cleaned off the IAC, and pulled that thing out, cleaned it, and wondered what the hell it was, since it wasn't mentioned in any of the diagrams.
If it was removed on 05 and up, that would be a good reason.
I'm still fighting with an idle issue, or, more specifically, a return to idle after high rev issue. I was trying to check all possible things.
Thanks for the input!
Now, it can only be inserted and aligned one way, but I still don't like it.

 

Back from the dead! I replying to this thread because after a boost leak test today on my Evo 8, I found a decent size boost leak coming from this exact part on the throttle body. I was just wondering if anyone knew the name of this part so i can order a new o-ring that is inside of it. Im attaching another pic as reference. I have been experiencing some low speed/rpm stalling issues when driving and this was the only boost leak I found. Any ideas on what its called?

 

had the same leak just got a set of orings from parts store found the one that fit put a little grey rtv around it and has been fine for years