M42 missing second throttle body plate?

[spud814]

Hey guys,

I just notice that my M42 is missing the second throttle body plate. What does this affect? Will this effect how my engine runs, and what is the second throttle body plate for?

-gil

[E30godz]

uhh yes it will effect it, it would be like having a huge vacuum leak i would assume....the small plate is for part throttle driveability

[spud814]

Anyone else with some insight?

[fabianyee]

can the engine actually idle without the 2nd butterfly???

[spud814]

LOL it's been running fine for the last year no problem. Idles just like my 325i.

[PanamaE30]

LOL it's been running fine for the last year no problem. Idles just like my 325i.

I worry for your 325i..

LOL j/k.. that's kinda odd. maybe you have a vacuum leak elsewhere nullifying it?

[Rob]

or maybe the m42's TB has a different design?

[PanamaE30]

The throttle body on my 318i's M42 and my dead 318ti's M42 look pretty much the same in design to my 325ic's M20...

obviously they're not the same, but fundamentally the same.

[spud814]

i clearly dont have a idling problem at all, but what is is the purpose of this second plate then?

[Stu]

The primary plate is the small (roughly 30mm) one, and the secondary is the larger, 54mm one--because the primary opens first when you step on the gas. The smaller one is used only for part-throttle, after more than about 1/8 throttle the secondary plate opens up.

Which plate are you missing, large or small?

Panama, all throttle bodies are fundamentally the same. Your 325i uses a ~60mm single plate that opens any time you hit the gas. The M42 uses two plates, as mentioned above. Not really a similar design to your M20 t-body.

[spud814]

OK guys, everyone has got it wrong, i have both butterfly plates. What i'm missing is the metal plate that is sandwich between the throttle body and the intake manifold. Sorry guys for the poor description and bad vocabulary.

[Rob]

that would be a gasket

[spud814]

LOL, nope, not a gasket, i know what a gasket is. This piece is a metal piece about 1/4-1/2 inch thick.

[Rob]

oh oh! I know. Does it have lines running to it? if so, its the heater plate, whatever its called. helps keep the throttle from sticking in cold weather

[spud814]

YES!!! From what i remember on my GFs 318is i think it does have lines running to it. So thats what that thing is, hmmmmm, interesting, i wonder how it effects my car since i don't have one.

Thanks alot ROB and everyone else that helped me out on figuring out what the hell that stupid plate is, thanks.