High idle

Mosquito · Post by **Mosquito** » Sun Jan 08, 2006 8:46 pm

My '87 carbed Tercel has a pretty high idle at startup (no tach, can't say exactly, but it's not 650, that's for sure--sounds like it's around 1800-2000). When the car warms up a bit, a stomp on the accelerator usually will bring it down under 1000, but sometimes further down the road, I'll coast up to a stoplight and the idle will be back up there at the high range. I've tried pulling up on the accelerator, no effect, so it's not a stuck pedal.

I've only had the car two months, so I'm not up on the gizmos--what could be controlling the idle that is malfunctioning?

brianp · Post by **brianp** » Sun Jan 08, 2006 9:16 pm

My sister's car just had a similar problem. Part of the sleeve on the other end of the throttle cable came off, and slid down under the plate which it pulls on ( I don't know what it's called). this made it idle quite a bit higher, but once I pulled it out, it went back to normal

MootsMan · Post by **MootsMan** » Sun Jan 08, 2006 9:48 pm

I had a very similiar problem back in the summer, immediately after I replaced the timing belt. Figuring it was something I had caused in my first attempt at a major mechanical repair, I took it to a mechanic to get it sorted out.....cost me $50 to find out the the cable had slipped out of place and was stuck in the wrong position.

takza · Post by **takza** » Mon Jan 09, 2006 6:52 am

First thing I'd do is take the air cleaner off...a job with this car...then with the engine cold...check the choke and how it works..use carb cleaner and some oil to make sure the choke is free...warm it up to be sure the choke sets in a closed position and then backs off after it starts...opens up when it's warm. Choke plate should end up almost straight up and down.

Mosquito · Post by **Mosquito** » Mon Jan 09, 2006 9:27 am

takza wrote:First thing I'd do is take the air cleaner off...a job with this car...then with the engine cold...check the choke and how it works..use carb cleaner and some oil to make sure the choke is free...warm it up to be sure the choke sets in a closed position and then backs off after it starts...opens up when it's warm. Choke plate should end up almost straight up and down.

Hmm, good idea. That also will allow me better access to the rest of the carb to check out the cable and such.

Thanks, guys. This will have to wait until next weekend, I'll let you know what I find.

(And here I was expecting a long explanation of A and B valves, EGRs, vacuum hoses, and so on. See? I *did* search--just didn't find anything that quite applied.

)

Typrus · Post by **Typrus** » Wed Jan 11, 2006 10:48 am

Does it calm down once it warms up? If so, you are experiencing high-idle/warm-up idle. I normally idle around 850RPM, but when its cold it jumps up to 1250, then climbs to a shocking 2900 by the time its warm. It will keep idling here, until I tap the pedal. Then it calms down.

Mosquito · Post by **Mosquito** » Wed Jan 11, 2006 1:40 pm

Typrus wrote:Does it calm down once it warms up? If so, you are experiencing high-idle/warm-up idle. I normally idle around 850RPM, but when its cold it jumps up to 1250, then climbs to a shocking 2900 by the time its warm. It will keep idling here, until I tap the pedal. Then it calms down.

Usually it comes down after a while, but it seems that some times, after having dropped down for several minutes, I will stop at a light or something, and the idle will back up high again.

My timing is a little too far advanced, I think, and my idle screw needs adjusting, but this back and forth thing, don't know what to make of it.

Oh, and this morning, for the first time, It was idling high/low/high/low/high/low in quick bursts, cycling through some sort of loop. That quit after a few taps of the pedal.

Just don't know, my 83 Tercel didn't have all this spaghetti, not sure if I like it. . . . .

Post by **ARCHINSTL** » Wed Jan 11, 2006 3:47 pm

Mosquito -
Check out a number of my posts on RPM Cycling. When warm and I revved to 2200 or so, it would automatically drop to 1800, then go again to 2200, then to 1800, then back to 2200, ad infinitum.
I solved this (temporarily) by plugging the "A" vac switch vac line. There are some lengthy threads in the Repair Question section. Try this and see what happens.
The car runs great without the "A" switch, but I do plan on installing an operative one.
Tom M.

Mosquito · Post by **Mosquito** » Thu Jan 12, 2006 2:55 pm

Are those vacuum switches available new? Are they pricey? Are there only used ones out there?

Post by **ARCHINSTL** » Thu Jan 12, 2006 4:05 pm

I have heard that they are available new- I believe a number of Toyotas used the same switch, but am not certain. Apparently they do not go South all the time. I have not checked yet, but I'll bet they are pricey (surprise-surprise...).
Tom M.

Paul · Post by **Paul** » Sat Jan 14, 2006 11:09 am

There is a fast idle adjusting screw on the back of the carb. I'd start here first. It comes into play when the engine is cold. You can follow the procedure on page FU-26 of the manual, or you can tweak it when it's cold right after start-up. It needs to bet set high enough to keep the engine from dying during warm up. Once you're off the choke, it's out of the picture.

As far as the high idle returning after warm-up, some troubleshooting around the TVSV might point you in the right direction.