Fd3s idling Problems when hot
 

Hello,
The car is an 1994 rx 7
Parts: redom ecu, hks downpipe, amemiya airfilter, Stock twins.
Mileage:46800 engine was rebuilded By 43k Miles
Sparkplugs Are new bur9 ngk
The problem is when its fully warmed up it idles not normal when I sit on Traffic lights it sometimes goes from 800 to 500 or all down to Zero And dies this happend 4 Times. Sometimes but very rare it is on 1100 rpm on Traffic lights when its At 800 it Shakes in my back And on The shift knob but when its higher At 1100 its not shaking anymore And under rev or driving shaking is not noticeable its only when idling. When idle went down to 300 i can rev it up to 800 that it doesnt die, then sometimes Misfire at idle.
1 year ago clutch was changed And flywheel before there was an mazdaspeed clutch with lightened flywheel And know a exedy clutch And oem flywheel from ebay. Maybe this could anything have to Do with it. But i thought then i Would notice it under reving it, too.
Maybe someone of you can help me out Iam Scared that The bearings getting worn out or anything like that.
Michael

Doesn't sound like a vacuum leak.
Download a copy of the Factory Service Manual (FSM) here: 1993 Mazda RX-7 Factory Service Manual It's also in the FAQ sticky in the 3rd Generation Section.
You will have to do some trouble-shooting on your own. I guess I start with checking the Idle Speed Control (ISC) solenoid. Maybe carefully remove it (be careful of the gasket) and clean it with some brake parts cleaner and a little WD-40. They will collect carbon over time. Starts on page F-82---> http://www.wright-here.net/files/man...ions_cntrl.pdf

With a "redom ECU" it's hard to say what's going on. In my own experience a lightened flywheel will also effect idle. Made mine 'hunt' or go up and down a little. You bought the car, it's going to take some initiative on your part to deal with it...or find a shop near you that knows the cars.

Thanks for your fast answer,
I have looked for vacuum leaks didnt found one, with The isc good idea will Look that up. The lightened flywheel was before in it.
But i bought an oem flywheel Used from ebay, Maybe i could have Picked one with a wrong counterweight, but i thought then i Would feel The vibration under driving And reving as well? Because under boost And driving everything is normal And car is runing with good power.

Now The fd is on The Shop And they Said its Running too Rich, but they Said i should Order a new cat. Can misfiring And rich runing caused By a clogged cat, or do i Have to search The Mistake in other Parts? It didnt pass The emission test.
Michael

There are so many potential reasons, perhaps the REDOM ecu isn't programmed correctly for your altitude/temperature, that's certainly possible as well.

Go to a good specialist RX7 shop to get that sorted.

I purchased a ecu from ebay but its The same, its misfiring At downshift i Have checked tps And compression with a normal compressiontest everything seems to be okay, The question is as we swapped The racing flywheel to an oem one from ebay. Are there different counterweights on oem flywheels or are they all The same anybody know that?

The stock flywheel has an integrated counter-weight. No separate count-weight as is needed with an aftermarket lightened flywheel.