TII secondary THB mod (pros and cons).

[FRED]

There's some small errors on this thread. To me worth mentioning an to others not worth mentioning or they would have said so. Anyway.

What makes the outer set of secondary plates ( the number two seocndary throttle valves) move is the DOUBLE THROTTLE DIAPHRAM in conjunction with the water thermo valve which is NOT the water thermowax device with the fast idle cam etc.

On a turbo thottle valve the number two secondary valves were designed to move/open slower than the number one secondary throttle valves. Driveablility thing. There is on a USA turbo throttle valve a dashpot who's plunger rides on a flat black cam and the dashpot is what makes the outer set (the number two secondary throttle plates) open a tash slower than the number one secondary throttle plates.

I find it hard to believe the JDM's have five plates and they all work together when they were built stk. But I never owned a JDM so take that for what its worth.

[rotorlips]

Originally Posted by FRED

There's some small errors on this thread. To me worth mentioning an to others not worth mentioning or they would have said so. Anyway.

What makes the outer set of secondary plates ( the number two seocndary throttle valves) move is the DOUBLE THROTTLE DIAPHRAM in conjunction with the water thermo valve which is NOT the water thermowax device with the fast idle cam etc.

On a turbo thottle valve the number two secondary valves were designed to move/open slower than the number one secondary throttle valves. Driveablility thing. There is on a USA turbo throttle valve a dashpot who's plunger rides on a flat black cam and the dashpot is what makes the outer set (the number two secondary throttle plates) open a tash slower than the number one secondary throttle plates.

I find it hard to believe the JDM's have five plates and they all work together when they were built stk. But I never owned a JDM so take that for what its worth.

well, perhaps I worded something wrong . let me try again here . all the jdm motos I have and not one of them has the thermo valve. the fast idle/thermowax is there but no valve, no vacuum hoses and no vac diaphragm . so, its almost as to wonder why the plates are even there . perhaps if I adjusted the dashpot for the plates I could get it to open a tad slower than the others . Ill have to compare to some other stock ones I have . all the USA ones have the vac hoses and diaphragm . works with the whole cold start thing . however, I have the cold start hooked up, no valve . just debating on wether or not to take the plates out or not . full stand alone ecu and bunch of other stuff . 100% working car all ready with no issues. hmm what to do .

[RETed]

It sounds like the US-spec ones are the only ones with the thermowax - think of it as a mechanical choke for cold start.
The thermowax prevents the double throttle from opening all the way, so it keeps the fuel mixture rich by resticting intake into the engine - how an old-fashioned choke would work on a carb.
Once the coolant gets up to temp and melts the thermowax does it release the double throttle plates to fully open up.


-Ted

[rotorlips]

so, been thinking and looks like im going to remove the plates and weld up the hole . looked at some 86-91 n/a thb's and they seem to work a bit different . once the thermovalve lets the vac go, the plates stay full open all the time.seems that the 3rd gen is set up the same way . just the turbo IIs seem to have this combination of valve keeping plates closed until warm up on USA models. not sure what their purpose is on jdm motors. driveability maybe? if they are for warm up then I understand but how they help for smooth driveability I have no idea if n/a and 3rd gen stay open once fully warm . I have a stand alone ecu so I can play with the accel enrichment and decay . hmmm