Slightly Rough Idle (not surging) GSL-SE
 

Well, I drove my RX-7 for the first time this year after working on it all winter. Overall I’m happy. Just a couple of little things. Most notable is a slightly rough idle.

Here’s my best attempt to describe it… The car Idles right at about 780-800 RPM with no surging. Seems to stumble/hesitate just slightly, maybe once a second. Watching the tachometer it looks like when it does this the RPM’s dip slightly maybe like 20 RPM. There’s nothing noticeable when you push the throttle above 1000 RPM that’s where it seems to smooth out. It’s rough enough that it rocks the car just a little bit. It does this whether cold or warmed up.

Car is a stock 1985 GSL-SE. No emissions. Still has AC. Racing Beat Streetport Exhaust.

Here’s what I’ve done recently that’s worth mentioning.
New Plugs.
New Distributor Cap.
New Rotor Button.
New Fuel Filter.
New Air Filter.
Wires are fairly new NGK’s.
Changed All Fluids.
Adjusted TPS.
Cleaned and lubricated BAC Valve assembly.

I’ve also noticed that upon cold start up, it’s not kicking up to fast idle. But struggling around 700-800 RPM and trying to stall. Usually I tap the throttle and it bumps up to fast idle. Don’t know if that’s related or not.

Does this sound like a timing issue? Maybe I need to advance the timing, or buy a timing light? Or is this just how a 25 year old rotary engine runs? I'd imagine it should idle pretty smooth since its a rotary. Spin Spin Spin VS. Boing Boing Boing.

Any help or advice is much appreciated.

ive got an 84 SE, and it runs a tad rough if you just barely give it some gas so that it revs up to say 1000 rpm, but it seems to be normal. Ive also got a fair ammount done to it, so i cant expect it to idle as smooth as stock. My best guess for your car would be to double and triple check that you have no vacuum leaks.

Did a little searching. Gonna check my variable resistor by the airbox to see if it's been messed with. I might try to smooth out the idle with that as a starting point.