86 NA rx-7, IDLEING AT 300 rpm?!?! WTF?? Help please.....
 

For some reason, in the past 2 weeks my car has decided it would be nice to idle at 300 rpm, thus causing it to die randomly at stops.

Turning the idle adjust screw doesnt help any eaither.

What really boggles me is that when I first start it up, it runs fine, at 750 rpmish for about 5-10 mins
then it goes to shit.

Any ideas how to fix this or what is causeing it?

I got the car about 2 months ago, it has a small tranny leak, after getting it I put new plugs in it "Trailing and leading" did an oil change + oil filter and topped off the coolent + tranny + power steering fluid.

It is an 1986 rx-7 GXL, automatice 13b. The fuel pump seems to have been rewired as it has a fuel cut off switch under the steering wheel.

have u made sure that your throttle cable isnt loose?

If that was the case wouldnt adjusting the idle speed still incress the idle over 300 rpm?

by that I mean the screw on top of the intake.

thinking about running some more fuel injector clearer through it but not sure... any reccomendations on a brand for it?

The idle adjust screw doesn't work unless you jumper the initial set coupler.

The throttle cable being loose wouldn't have a thing to do with a low idle.

I just picked up a car like yours a few weeks ago. You can also try to adjust the idle mixture to see if that helps. I am hoping this is it since mine was way off when i got it. You will find it on the passengers side right in front of the shock tower. It will have a small flat head adjuster screw to turn and it will have an arrow showing that turning to the right is richer and left is leaner. there is some good resources out there for how to adjust the mixture and idle together. Good luck!

So, what would? lol... I guess I could check for a vaccum leak by having a friend listen for a hisss, rev it up high let off the gas see if it makes a hiss.

Someone also said something about a BAC? what ever the hell that is.

I dont think changing the fuel air mixture would fix the cause of the problem, meerly compansate for it. I would like to fix the cause if I can, though wouldnt running a richer fuel air mixture give me more power also?

Woot for a newb wanting to do it right. :D Check all of the linkage and make sure it's right. I doubt you have a vacuum leak since the idle would be faster because of a lean condition. The BAC might be messed upp too Check it in the FSM.

"Woot for a newb wanting to do it right."

I am a newb but if their is one thing my father taught me, do it right or pay for it later on.

Now you said to check the bac in the FSM, what does FSM stand for? Sorry just starting to learn about the stuff so hope you have some patiance :)

fsm is the factory service manual.

ah, lol I know where its at. Going to take it off and clean it up and see if it helps.

pulled off the bac valve, cleaned it with carb cleaner. didnt help at all, Going to check for vaccum leaks next, any advice on how to go about this? I do not hear a hissss type noise so if it is a vaccum leak its pretty big...

lots of vaccume hoses to check son. maybee fiddling with the screw will help. i dont know.

mine runs fine. if it revs higher for a minute when you start it, thats normal, but it should be a coule grand more, not a couple hundred more.

Where is the connector you have to jump to adjust idle? I'm at 500rpm now, and it's fine, but I'd like it a tad higher to compensate for all the stuff I'm running right now (carputer, etc) :D

Initial set coupler... You can get it from there.

heh where is the intial set coupler?

Ok, seriously though, I still say please at least try to play with the adjuster screw for the A/F mixture at idle. I have worked on piston motors for years and in the past year I have played with rotory's and the idle adjust is similar, especially for fuel injected cars. If a car is either running to lean or to rich then it will run poor. Just hook up a jumper to the initial set coupler and then turn the rich/lean screw next to the passengers shock tower until you get the highest idle. Then turn it counterclockwise until you get something like a 50rpm drop. Then adjust the screw on top of the engine until you get the idle to around 750rpm. Take the jumper wire off and hopefully you will be good.

It is so easy for previous owners to play with the screws and then get them out of adjustment that I can't hurt to play with it yourself as long as you do it correctly. If you are worried at all, just mark the screw where you started out at.

You can do it! ;)

Oops, almost forgot. The initial set coupler is on the drivers side near the front of the car next to the coil. There will be a plastic connect with two female connections built in it. You just put a wire in both connections and you will be good. The FAQ has some awesome notes on doing this. Look in the shop manual section.

Ok, so cleaned the bac valve with carb cleaner, it was semi dirty, didnt fix the problem.

Clearned the throttle blades, didnt fix the problem "whats up with the top 2 being open and the bottom one closed when sitting?

Tryed to adjust the idle speed, I put a jumper in the intial set coupler "I am pretty sure its the right one, green connecter with 2 females by the front set of ignition coil thingys, in front of the strut.
After jumpering it, it had 0 effect turning any of the screws higher, couldnt get it above 400 rpm.

So still at a lose for a fix... Not sure why the adjusters arnt working.

Are you going by the factory tach? From what I understand they are pretty innacurate for making these adjustmets. Hopefully someone can correct me on this. As far as the low idle, Have you checked all of the linkage on the TB? I assume that your car is a S4 since the idle mixture was mentioned. I think you have a linkage problem. Good luck.


(Edit) I reread the first post to confirm the car is a S4.