i have picked back up on my project car. all thats left to do is fix this anoying idle. iv checked the compression, and its good even on all faces. iv checked the bac, all the solenoids, disconected the o2 sensor, pressure sensor to see if that made any difference but they did not. just reset the tps. have looked for vacume leaks with starting fluid with no luck. havent tryed the propain yet (i need to go get a bottle). well any way it runs fine when initaly started at about 1500 rpm then drops to 1k and starts reving a hundred rpm or so. and it dose it if u hold the throttle so it revs to 2k it will bounce also. its not just a rev and decel. it revs then sounds like its dieing sputer and shake then revs a gain. like something it kicking on and off. i tryed to make a good sound clip but the voice recorder on my mp3 player destorts like crazy : ( dont have a video cam. i know my wide band is on its way out. o and the car was a auto i swaped a 5 speed into. 89 gxl. i have the bac screw on top of the intake almost all the way in, 1/4 turn form bottom, to get the idle down to around 1k. and closing it anymore doesent change anything. also the fast idle cam is disangaging. iv already gone through the throttle body. iv been reading the FSM and im starting to think fuel system. but when i rev over 3k is dosent seem to do the bounce. and runs fine at higher rpms. so i think im geting plenty.

thanks for any advise.

 

I have a similar problem with my '89 gxl.. Although I am new but very eager owner of a rotary.. So I don't know enough to say it is the same problem..
With mine, I let it warm up the rpm eventually comes down to about 750-800rpm then (for this next part bare with me, I'm a rookie) it sounds like my brothers 87 nissan when his choke is stuck on.. its about 1.5-2 seconds of smooth then it sounds like the rpm drops to the low hundreds(100-150) for about .4 seconds, then back up.. it is very rhythmic and seems to never vary.. when I rev it to about 2850rpm-3000rpm it seems to stop..
anyways, just thought I would put this up here.. sorry in advance for my nomadic explanation

This is my car..

 

vaccume leak/TPS is bad, bouncing idle's are almost alway's a result of a vac line that isent sealing right, replace your vac lines with silicon line's they can be bought from mazdatrix.com or bakersperformance witch is next to mazdatrix in your guy's case you would have to order them...and dont use propane, get a can of carbcleaner and spray the intake manifold first then the rat's nest..if the idle goes higher then its def. a vac leak in the area that you sprayed. good luck.

:AA:

 

You mentioned that you set the TPS. Did you go bac and reset the idle speed ? If the idle speed is too high, you'll get a fuel cut issued at closed throttle and that results in bouncy idle. Make sure engine warm idle speed is set to 750.

After that I would say there's a vac leak you haven't found. When I battled this problem the problem was a leaking gasket between the UIM and the LIM. If you're like me you don't want to hear vac leak because they're so damned hard to pin down. It would be much easier to turn a screw and fix the problem.

 

all continue searching for a vac leak then. from what it sounds like. but why not use propain. it will let me know if there is one and the rough area, then all pin point were at with starting fluid. thanks.

 

i went in with a bottle of carbcleaner and starting fluid and have found a leak. i think its the plug on the back of the intake that would go to the auto trans. i put a plug form a used motor on it but aperintly its gotten to hard to make a good seal. when i sprayed it my engine would sputter out instead of reving up. i think thats cus my bac screw is all the way shut and so it starts runing to rich when i spary it. since its such a small leak it still runs good under load so i hope thats all it is. : )

 

i was wrong about the cap its all good but it is definatly in that area. lots of vac lines running through there. also a joint in the intake manifold. of corse the leak has to be on the back side where its HARD to see. any slick tips to nero the search down a little more?