Tercel idling rough

[bobthebiker]

I am stumped on this one. my 86 Tercel wagon runs great, but at idle, no matter whether its in gear, or not it will run oddly. by that I mean it will run fine for about 20 seconds, then the rpms will drop like it wants to stall out, and recover to do the same thing again. it has stalled a few times because of this issue.

filters are new, fuel is clean and fresh, and as far as i know it has not been messed with in any way. please help me figure this out.

I'm very mechanically skilled so anything that can be suggested I am capable of.

Also, are there any mods I can do to further increase the already decent fuel milage this car gets? right now I'm getting around 25-30 mpg from it, but I think theres ALWAYS something more that can be done to increase the economy even more. perhaps a larger exhaust pipe? the one that it has seems quite small, possibly increasing to a slightly larger pipe would allow the motor to breathe a little better.

Thanks in advance for any and all help provided.

[ARCHINSTL]

My '86 SR5 has a similar symptom, but after once achieving 1800, it then goes to 2300 and back and then up again, ad infinitum. I temporarily solved it by plugging the vac line to Switch "A" (immediately next to the EBCV) and reattaching it, but leaving the electrical connection attached. This was a maddening malady, making for some not-too-smooth driving.
The only downside is that the revs do not drop to near idle during shifting, but to a little above that; this has no real effect on driving, per se, but probably wastes a bit of fuel. I still get 30+ on the highway, though.
I wrote the Mothership in CA, but have yet to receive an answer...

Now - others with the 3AC have had your problem; mine is just similar. I do not know if my fix will work for you.
The larger exhaust pipe mentioned would be of dubious help. Your gas mileage is fairly typical - the car is 20 years-old, with how many hundreds of K miles?

Incidentally, DO join our Wagon-only Club at www.tercel4wd.com, or the Forums at http://Tercel4WD.com/forums . There are 400+ members owning the Wagons only; primarily 4WD, but also 2WDs. Automatics are welcome as well. Not much on neon and aero and audio and the like, but primarily concerned with keeping these little guys running. There are a lot of very mechanically-talented people in the Club, and a number of threads addressing the very subject you broach - but as always, do a Search first (there are not ten thousand threads to search, either...).
There is also an FSM that you can download. Members are very helpful and also post new pop-ups on eBay and various CraigsLists.

Tom M.
PS: "biker" as in motorized or as in pedal-powered? There are a number of each in the Club, and I owned a bicycle store here for 30 years.