j_tso

iTrader: (2)

car: 1982 S, stock engine except for shutter valve plugged.

Here's how things happened:

A few days ago, the car starts idling high in the middle of traffic, 1200-1300 rpm. It did this couple of times over the last year, but would go away after a minute, so i think this was a developing problem. This time it wouldn't go away. I assume it's a vacuum leak so I'll find it the next day. Then the choke won't stay out. I went ahead and sprayed some carb cleaner around the carb, didn't find anything, but i don't think I was spraying in the right area.

I did some tests from the Mazda Carb Manual:
The choke switch has definitely crapped, I tested with a multimeter on the connector (1 out of 2 tests worked), and jumped the temp sensor on the water pump. No go.

The relay is good.

The No. 2 Choke Diaphragms and Choke delay valve tests didn't really work. The No.1 Choke Diaphragm test did work. I'm kinda clueless as to what to look for now, since the vacuum lines going to all of those were good and the manual doesn't say what to do if they don't work. Are there any other things I can test ?

I fiddled with the idle speed screw to superficially solve the high idle, but now when the car wants to act normal sometimes, the idle is way low, and when the AC is turned on, the idle goes as low as the tach can read, but the car doesn't die.

So, would the Choke switch cause a high idle? how hard is it to replace? Did a vacuum leak and broken switch just happen at the same time? The two seem unrelated to me.

j_tso

iTrader: (2)

UPDATE (still at it) :

The high idle "fixed itself". I hate that. The choke works intermittently, but I've gone through all the components.

What holds the choke out?

My understanding is that it's electromagnetic, so a vac leak won't stop it from working. I've tried another choke switch; choke/check relay and temp sensor are working. The choke heater works, not sure if it's related anyway. What else am I missing?
If I hold the **** out with a penny, it warms up normally, but it's annoying when I drop it under the seat.

cjrx7

Behind the choke **** there is a black box that has that electromagnet in it,it is right behind the **** and inside of the dash,play with that box or just try to get another. I would guess that when the idle shoots up it is holding it's normal amount of vacuum and is where it should be,but then the leak worsens and it "goes back to normal" the idle speed screw should be barely used if at all,see how much vacuum you pull under different settings,check the vacuum tube that is in the lower rear of the manifold also(big one)

j_tso

iTrader: (2)

Wow, thread revival!

I did switch the choke cable assembly with another one: no go. I'm now assuming it's an wire broken internally or something along that circuit.

That vacuum hose on the lower manifold did crap out recently, by that time the hole was so big, it created a really low idle, almost making the car die.

cjrx7

Umm maybe linkage for the fast idle bar is sticky,what all is stock,everything but the shutter valve right? I just recently had a bitch of a time tuning one I just bought,aside from all sorts of other things, the shutter valve needed to be totally removed because it was leaking through the vacuum diaphragm of it,I had to block the exposed ports,just drilled and tapped plugs to fit. I also had the chance to address many other things with the manifold off.

j_tso

iTrader: (2)

Do I just make sure the fast idle rod isn't stuck? Dust off the grime with carb spray?

Yes, everything is stock minus shutter valve, all emissions equipment is attached.

There hasn't been a high idle like my first post since I replaced that AAV hose, but it does sometime wander at or past 1k rpm, so it's probably another little leak somewhere. I'm replacing all the tubing with silicone soon. It's a little annoying, as I've wasted half a can carb cleaner trying to find a leak.