I'm still trying to understand the roll the throttle opener plays
fenixus on ToyotaNation wrote: it's only function is to push the throttle plate open when engine is shut off (no vacuum). it's sole purpose is to prevent throttle plate sticking/freezing to throttle body in dusty/dirty/freezing climates.
Here is a video of the Throttle Opener
I may have a throttle body or two from a different engine to practice on.
Hi Nate, I passed your phone# on to Collette by email yesterday, I did get your message, thanks for calling. She hasn't called me back yet-let me know if you do get in touch w/ her. I will keep trying- she might have loose ends of other business at issue.
Yes I wondered 'bout that gizmo on that TB- first thing I thought of was it looked a lot like a throttle dashpot as found on some old carb's, but those were usually there to keep a suddenly-closed throttle from slamming closed and sticking. Seems like a factory band-aid on this TB. I've noted a few Asian cars from the 90's had a prob. w/ dirt/carbon buildup around the throttle butterfly causing erratic idle rpm's. This example is sorta like that but reversed. This is a dashpot setup to open throttle slightly at engine shutoff-w/a vacuum pull-off to defeat the dashpot w/engine on. This also operates opposite of the old throttle position soloniods found on smog-era cars. W/ retarded dist./cam timing common on 70's/80's carb'ed engines the idle RPM often needed a greater throttle opening, but that could cause dieseling or "after-run" at hot engine shutoff. So idle RPM was set via an adjustment screw on a solonoid that energised w/ ignition on. W/ ignition off, the solonoid screw would retract to close the throttle and so prevent run-on.
The idle Solonoid is analogous to our Idle Air Control (IAC) systems of today. There's sumthin' from the Way-Back Files.
With age the diaphragm could be potential vac. leak, check yours to be sure, Nate.
Gadgetman Reno, NV
Ok great thanks! I'll let you know if there is any contact.
So when it comes to cutting a groove on this throttle body I want to make sure the throttle opener is not messing with the throttle plate position. If I understand correctly, ignoring the throttle opener can cause the groove's location to be further away with the chance of lowering the groove's efficiency.
I did check for vacuum leaks on the throttle opener, map sensor & lines, brake booster & check valve.
I still need to find out how to properly check the emissions related vacuum lines for leaks.
Hi Nate I just left another phone mess/ w/ Collette w/ your # in it. she's been nutso busy w/ some real estate business, I know that can be hectic!
OK for your TB- what needs to happen is to determine the engine-on-at idle throttle position. I'd have to take another look, but is there a throttle stop adjust. screw on it? Put another way-w/ engine on, the dashpot retracts, right? So when it's retracted does the throttle plate fully close-or is there a tang on outside of throttle shaft contacting an idle stop screw? Heck simpler is to just remove the dashpot, and the throttle return spring on the shaft will put the throttle in it's idle position, long as I'm not missing anything else. I'll need better clearer pics of this wolly-bugger to say for sure, but I'm betting this TB is just about like any other except for the dashpot. Still scratching my melon as to why Toyota felt the need for the dashpot, musta been an issue w/ throttle sticking, why else? Don't usually see dashpots on TB's it's a sort of throwback to like 40-odd yrs ago. IF the throttle closes fully w/ dashpot retracted or removed, as in there is no idle stop screw- then that also tells me the IAC is always open some, that would be the only way air can enter if throttle is completely closed. IAC may even be open a little always, even if there is a throttle stop screw. Possible scenarios, just guessing here without benefit of holding it in my hands.
Also-remember to clean the IAC pintle and passageway well while it's off, I do this as part of initial TB cleaning, some carb. clean, a toothbrush and a dental pick for any hard deposits. On some engines, there have been cases of sudden uncontrolled engine RPM's caused by a dirty IAC sticking open, have heard stories of cars suddenly leaping ahead into an intersection w/o driver input, very bad news!
Would be good to see pics of this TB, if you clean it it will be easier to see what's up. But- it may also be useful to first treat it as we do w/ drive by wire GM TB's like Chevy Vortec 5.3's- before cleaning, look for the dark carbon deposit in the throttle bore right under the throttle blade-that will be another telltale of the "natural idle" position of throttle blade. I'm betting that when the dashpot is off of it it will be in that position, but I'd examine it carefully and be certain.
This, Nate, is all part of being a real Gadgetman, often there is "detective work" involved! I'm glad you have brought this one to our attention, gives the chance to think of this stuff!
Gadgetman Reno, NV