For anyone searching, I had this problem and the cause was that my O2 sensor was not connected.

 

the bad ninja..... can you give details on your problem when the 02 wasnt
connected? i kinda have the same problem with a 88 gxl with a na 13b. heres the
thing with mine. it idles at 900 /1000 rpm. constant idle tho. when i lightly step
on the gas pedal to rev it to 2000 rpm. the engine will not stay at 2000 rpm. it
will bounce to 1500 rpm than than slightly above 2000rpm with the gas pedal held
in the same spot. and it bounces back and forth. is there only one primary 02 sensor? my 02 is on the back hosing header pipe with no wire to it at all. gone.
i dont even know where the connector on the engine harness is for it. anyone
with some knowledge that can help please chime in. thanks.

 

I was getting a big, rhythmic idle pulse that was enough to stall the car at times. I solved the problem by just running a wire from the sensor through the firewall to where it connects to the computer, under the passenger side footwell. Here's a link to the manual (you want 1988 wiring diagram) so you can figure out where to hook up your wire: http://wright-here.net/cars/rx7/manuals.html

 

Been struggling with a high idle. At one point thought I had it all dialed in. Then Friday morning I wanted to go for a short drive., before heading out of town. once the car had warmed up the idle started bouncing between 1350 and 1650 rpm. After the drive I did a little trouble. Shooting. TPS 1volt , sprayed around possible leak areas with carb cleaner. Nothing of note.
Took it out again today, put about 5 miles on it. Accels smoothly, seems strong. Hit 5psi by accident let off the pedal as soon as it boosted. I was in 3nd at about 3800 give her a little ahead of shifting to 4th. Oops.
The WB shows lean as I accel from 1500 to around 3000, 15 to 16 afr. Then when I hold steady throttle it drops to 12.5 to 13.1 as I cruise alone in 3nd on a small back road near my house.
When I was installing the TB a while back, I noticed the the secondary throttle plates were cracked open a little, but the adjust screw for them looked untouched. So I let it alone. Thought maybe Mazda had left it that way. Could this be acting like vacuum leak and causing my high idle, and now bouncing idle?

( I have a S4 JDM TB, no double vacuum valve or double diapham) Pinched off the BAC, got no better.

 

I had the same exact problem. I replaced my TPS and it didn't help that much. I ended up removing my throttle body, unclogging the Coolant passage (it was getting stuck on cold idle), cleaning the entire TB, Lubricating spring and hinges, and finally setting all the openings and alignment marks per the factory service manual. Good luck. It's a pain in the butt.

 

I was afraid of that, The TB has to come back off. Was hoping for a miracle ( no short cuts allowed.)

 

TB is easy. Don't worry. Took me like 20-30 minutes my first time. Be happy your not replacing the vacuum lines below the intake manifold.

 

Got the bouncing idle to stop. Primary throttle was not closed all the way. Throttle cable seemed like it had plenty of slack. Not true, adjusted it a bit and now have a steady. Still to high but steady. Idles around 1050. Still have another vacuum leak to find, TB to come off this weekend.

 

Got the high idle fixed, was the Dashpot. It was adjusted too close, wasn't allowing throttle to close. The plunger was Collapse as well. Need to find a replacement. This part serves a function and with out it drive ability suffers for sure

 

Sorry about reviving an old thead but i cant seem to find any informatiom on what i need
So i have a 1988 s4 gxl and everytime i rev and then take my foot off the gas the idle drops to like 300 then slowly climbs back up to 750 is this a problem i need to worry about?

 

you probably have a vacuum leak, which is unrelated to anything in this thread. the S5 can pulse fuel cut if the idle is too high, yours is too low and sounds likely due to a lean condition.