Ok. I idle at 1000RPM's even, If i rev up kinda high (4000RPM) and let of the gas the entire car will vibrate and run rough all the way back down to 1000RPMs Not only that no mater what teperature it is or if the choke is or not the car will smoke for like ten min. even if i dont give any gas. I wanna know what is wrong and if this is an easy fix. Thanx

 

okay, a stock 84GS is s'posed to idle anywhere from 850RPM (perfect stock off factory floor) to 1200rpm (still healthy, but has had a long life)

The shuddering back down to low RPMs is probably due to failure of the shutter valve. That's a little valve in the intake manifold which helps the car decelerate without shuddering. I don't know much more about it, but maybe someone else here can help a bit more about it.

The basic fixes for that should include:
- rebuilding the carb (fairly easy to do or get done for you)
- removing the rat's nest (find the tutorial in the facts seciton of mazspeed.com)
- and maybe checking up on your fuel delivery/fuel filter and ignition systems to make sure they're working well

For the smoke we need more info. What colour is it, how thick is it? Perhaps your Oil Metering Pump is stuck open. The oil metering pump injects a little bit of oil in with the air and the gas to lubricate the apex seals along the insides of the combustion chamber. The result is that your car is DESIGNED to burn a bit of oil. It's supposed to burn a bit. If the smoke's slightly bluish I believe, that's oil.
You can rebuild the OMP with a kit available at lowesperformance.com, it's cheap and easy to do and will get that oil-injection system working properly again. If the OMP were to fail and give too little oil instead of too much, it could sieze your engine, requiring a rebuild. Burning a l'il too much oil is okay, for now, old engines tend to do it.

If the smoke is white, it *might* indicate failed water seal. That's... not good. A hard fix indeed. I don't know much about it, so hopefully someone else can fill in the blanks on how to tell what that is. I know it entails an engine rebuild if it's serious.

Anyway, with any luck the shuddering problem is a relatively simple and cheap fix, and the smoke is too. Worst case scenario, you might need an engine rebuild, but listen closely:

Anyone who tells you these engines are "hard to rebuild" or "special factory-only rebuilds" are bullshitting through their teeth. There are rotary garages who can rebuild them for pretty good prices, especially if you do it *before* the engine fails and don't need replacement parts. And whilst you're in there, an extra 200-250$ can get you ported intakes and exhaust ports which gives you a major increase in horsepower for not much compared to the rebuild.


Whatever it is, stick with it, you'll be glad you did when the car runs well

Jon

 

Does it honk on the way down from idle? Shutter valves arent that bad to replace, drivers side of carb under it. Remove the small vac tube next to the big one and see if it still does it. If you drive it does the smoke go away quicker?

 

What RPM's is a stock `84 GS supposed to idle at, and why does it smoke for so long?
750, and cause it's fucked.
Naw- it's probably the manifold gasket "O" rings gone rotten like vipernicus42 said.
Are you losing coolant at a slow rate? Is the smoke white and sickly sweet smelling?

The idle is high, but does'nt seem high enough to blame on a vacuum leak. You should'nt be reving it that high when cold. No higher than 3K till fully warm if you want her to last. The when she's all hot and ready for ya, up to 7K all day, provided all else is in good working order.

Overheating can kill her dead in just one shot...like a craps shoot. (Maybe, maybe not).
When getting a new Rx-7, always pay special attention to the cooling system for a while before you start driving the **** out of it- just for the piece of mind that knowing the system is good affords.

 

ok.....so i like in the S.F. Bay area in Cali so removing the nest is out....i can do the carb thing....is there an easy way to check the manifold gasket...i really dont feel like tearing it all down to find out its not the gasket. The smoke is a whiteish blue...typical of burning oil from a bad head gasket in a boinger...im not too familiar with a rotary but i have enough machanical knowledge to understand the concept. So i could rebuild it if it came down to it.....but im wanting to just replace some parts and call it good.