XT6 throttle body on spider EA82T's

[subyrally]

i have a spyder manifold with the xt6 throttle body on it. it ran like a beast at high rpm, but it would often stall out at idle or run very bad at lower rpm's. the main difference being that it doesnt have the little valve thingy on the side of the throttle like the 4cylinder tb's. i think its the little motor thingy that controls the idle speed for peower steering and a/c, or something like that. i was in the works of making an adaptor to run the little thing on there. but i never finished it. basically, sinc the xt6 tb doesnt have a place for the valve/motor/thingy, i got some brass brake line adaptors and vaccuum connectors from the parts store and started on making something that might actually work if i ever finish it and get another ea82t running again.

 

but if anyone around the central maryland area has an ea82t with the spyder manifold and wants to help out and use the xt6 tb for a bit, let me know, i would like to finish the project. granted, i might try to use it in the brat when the time comes.

[joostvdw]

that kind of confirmes what I just said, the EA82T benefits from the extra air

 

What do you mean about the about the idle thingy? The 4 cilinders don't have an active idle control or the likes, they do have an high idle solinoid that kicks up the idle when the AC is on.

 

Perhaps the idle sufferd from the increase in air since the idle was designed for the 2.7 instead of 1.8?

[joostvdw]

sorry double post, trying to delete

[subyrally]

the xt6 tb has absolutely nothing to compinsate for the idle, not even an adjustment screw.

 

if you have the standard ea82t throttle, when you look at the engine from the front, on the back right side of the tb, there is a six sided "thing" that is about 1.5"-2" tall and usually has a wire coming out of the top of it to a single wire plug. i have seen acouple that have a second wire that i beleive is grounded. if you unscrew the "thing" from the tb, there is a slug of metal with a rubber tip on the end all backed by a small spring. from the looks of it, it sits in a conical hole at the bottom of its hole and there looks to be a tiny hole above the hole at the bottom. i wish i could describe it better, but putting thought to paper, so to speak, has always been hard for me.

 

either way, its like a small pintle valve that routes a small amount of air around the throttle plate.

 

 

i think its called the idfc motor, or something at least close to that.

some of the other ea82t guys might know a bit more about it, but i am still learning as i go.

 

 

that kind of confirmes what I just said, the EA82T benefits from the extra air

 

What do you mean about the about the idle thingy? The 4 cilinders don't have an active idle control or the likes, they do have an high idle solinoid that kicks up the idle when the AC is on.

 

Perhaps the idle sufferd from the increase in air since the idle was designed for the 2.7 instead of 1.8?

[joostvdw]

What you are describing sounds very much like the high idle solinoid I was mentioning:

 

 

If the engine runs better with a bigger TB that means that the TB is the limiting factor? but doesn't that also mean that the engine benefits from bigger intake piping (if it's a turbo with IC) or maybe even bigger intake runners?

[discopotato03]

In the Subaru WSM that "thingy" is called an FICD or fast idle control devise .

 

Its just an on/off solenoid that opens a small passage to pass extra air when the air con is running . The engine has to power the AC comp and blower fan so it needs a little more air at idle so as not to run at 400 rpm .

 

I tend to think that a larger throttle valve would let in a LOT more air than the std EA82 throttle (spider and L MPFI throttles are the same size) when opened suddenly . Now the airflow meter will measure how much air is going in but the computer won't know to dump ALL in the extra fuel when the throttle is opened quickly at low revs - big transient . Remember it can't tell what size throttle the engine has - all it see's is the TPS idle on/off and potentiometer voltage out put . Often the potentiometer won't move as far or as fast because a larger throttle passes more air for per degree of rotation than a smaller one .

 

Cheers A .

[subyrally]

that was the bit i was reffering to, but ive been thinking about it, and if its only for the a/c, then it shoukldnt have been what was causing my issues, then again, i think it comes down to tuning, or the lack there of.