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Problem: In warm temperatures I would drive my car for an X amount of time, as soon as I shut off my car and turn it back on while the engine is still warm, say after stopping for a quick moment at the store, right away my engine idles up at above 1200 rpms. I correct it by pulling up on my accelerator with my foot and it comes back down to normal idle speed. If stuck in stop and go traffic, that remedy eventually doesnt work and the idle just gradually climbs (sometimes at 2000 rpms!). I took my car in for a scan at Mazda and the computer said that I definately needed to replace my distributor and possibly my o2 sensor. I replaced my distributor last week and the engine light turned off, but a few days later the engine light came back on and my rpms went crazy again while stuck in traffic. I guess I need to get re-scanned again. Does this problem sound like it has anything to do with my sensor? My gas mileage has dropped and I know that o2 sensors play a role in air/fuel mixture, but does it also affect the way an engine would idle?

Sounds alittle like you need a new radiator. Thats the same thing that happened to me, but I'm assuming thats not your problem if Mazda checked it out and didnt say anything about it.

I've been having idle problems like that lately too after cleaning my throttle body out. After doing some archive searching, I've read that the spring on the throttle body looses its restoring power over time, and at this age sometimes requires a helper spring to help close the throttle body all the way. That's what I would suspect if pulling the gas pedal out remedies the problem.

I've had this problem for quite a while now, too. During stop and go driving, I'll have to pull up on the pedal to get my idle down again. I have the ZE engine, and I always thought the problem was in the TB itself -- maybe that the throttle cable didn't have enough play. But then, I guess that wouldn't explain why this problem doesn't happen ALL of the time. I also thought maybe the IAC was a source of my idle problems in general. I have an extra ZE throttle body laying around that I've been meaning to swap, but I just haven't gotten around to it.

Anyone else have ideas why this happens?

Yeah, I'm also having this problem. Can fix it by pulling the pedal out with my foot.
Hope someone has a remedy.

Next time your guys' idle does this, leave the car alone and get out under the hood and see if you can push the throttle pulley back a little before it hits the back stop completely. If it's got a tad of play before the backstop, then I'm sure a helper spring will help remedy the problem.

How exactly is a helper spring installed on the TB?

Here. Found this on ProbeTalk:

How to: TB boring + fix bad Idle + TPS myths

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Below is a responce to a PM asking for a rundown on how to get a perfect Idle after a TB overbore.
I posted it here to help all of those with poor idle quality, weather you have an overbored TB or a stock TB doing the steps listed will help to cure a poor Idle.

I also want to make another attempt to dispel some of the myths about the TPS sensor. The TPS is nothing more than a voltage resistor supposedly with an "off" (no contitunity switch. It works exactly like those "dimmer light switches with the dial that you turn to brighten/dim your livingroom lights. How Ford has the nerve to charge around $200 for a TPS I will never understand
Adjusting your TPS is not the right way to raise idle RPM's. If your TPS is properly adjusted you can unplug it durring idle and have zero effect on idle speed or stability. You may however get the TPS error code on your check engine light.

Have you adjusted the backstop screw that controlles how far the TB closes?

Your new TB plate should be oval shaped not round (because fully closed is 100* not 90*). Make sure whover fabed it made it oval.

The plate should have egg shaped holes for the two screws to go through. If things are not seating right you might try loostening the two screws and opening/closing the TB softly to let it seat right (move around on the egg shaped holes) then retighten. The back of the screws are supposed to be peaned so they can't back themself out though + red locktite is a good idea.

Also be sure that it's not your TPS that is causing the Idle problems. Bring car to opp temp, let idle, unplug the TPS wireing clip. Your car should Idle exactly the same with the TPS connected or un-connected. If you note a diffrence in idle when you disconnect the TPS than an improperly adjusted TPS is partly to blame.

In addition to the backstop screw there is the bypass screw that needs to be adjusted.

Stock + 65mm TB plates side by side Note the slightly oval shabe of both of them.
My properly fabed butterfly seating perfectly in the overboared TB
Might as well mill the shaft down and install countersunk flatheads
Wide Open

Do these steps in order (its easiest to do the first two before attaching the TB to the Manifold)
- Clean TP + make sure IAC is clean and functioning. (whoever bored out your TB could have gotten some metal shavings stuck in the IAC area.
- Set backstop screw and mess with the seating of the holes mentioned above if need be.
- Make sure you have rock steady proper vacuum. Put a vac tester on if need be.
- Set throttle cable to proper amount of slack.
- Bring car to opp temp.
- Unplug TPS
- Adjust Idle via Idle air bypass screw.
- Plug TPS back in and calibrate using your method of choice.

- It may also be necessary, and is a good idea anyway to make sure your ignition timing is set to specs.

Thats it.

I have considered installing a helper spring (screen door type spring) to the TB to make sure the TB always seats completly closed, But after doing the above steps, I now have a perfect Idle all of the time

Hope that helps. It sux not having a good strong constiant Idle.

Brice

just wanted to say thanks for all your replies and info. despite all that, I fixed the problem. Set up: I let my car idle for around 15-20 mins. and then I revved the engine to get it to "stick" at a higher rpm. Don't pull back on the accelerator. Get under the hood and just merely give the accelerator cable more play by loosening the fastening nuts where the cable comes out of the tubing leading to the throttle. Open up the throttle approx. 75mm and then tighten the nuts again. Open the throttle a couple of times and the engine should calm back down to it's normal idle. You might have to try this a few times to get the right amount of play or slack in your cable for this to work. I hope this helps any of you out. Let me know how it turned out.