My name is John I'm 22 I live in Cheyenne Wyoming. I have a 1985 Mazda RX-7 nice and clean still with ALL original parts. I have a question about it though. When you start it up and have it idling the rpms go back and forth and its not a normal back and forth. Im trying to find out what the problem is and maybe how much. Can anyone help me?

coils and/or new spark plugs, maybe.

Is it a rough idle, does it hold an idle or does it stall?

Welcome to the club.

I would assume you have a 12A with a carb? Have you done anything to the car to find out the problem? New plugs, cap and rotor, fuel filter, etc? Does the car run fine other than the idle? Does it still have all the emissions?

With these answers I can probably get you in the right direction.

Took it to ford edlearship they said it might be something with the engine. Runs great just a rough idle and it holds except for the going back and forth probably between 1000 and 1500 rpms. other then taking it to Ford I havent done anything to it yet.

aaa....k

The ford dealer will know nothing about the car. Have you had the car for a while?

It should idle at about 700rpm. I would start with changing all the fluids including coolent. You would be surprized how much that will help. Change out the fuel filter as well.

Change the plugs and only use the factory NGK plugs (BR8EQ-14). Replace the cap and rotor, and inspect the wires for age (maybe replace them). Check to see if you are getting spark to all the plugs (easiest way is pull one wire at a time with the car running and see if the idle changes). Sometimes if the trailing is not working properly it will still run fine but not idle right.

If these don't work, I would look at vacuum leaks. A vacuum leak could happen anywhere on the rats nest etc. It could be hard to find. You could also have a bad coil but that doesn't happen often with these cars. The coils usually get weak but don't fail. If you deside to replace them get MSD Blaster II coils for the car (Accel coils will not work, I learned the hard way). You might also need a carb rebuild but that would probably cause it to just run badly.

Ah ok Ill start going through the stuff and check them out. Thanks if I have any other problems I'll let you know.

My bet would be on a vac leak. You can use a propane torch and leak propane (don't light it!!) in the engine bay around vacuum hoses and such and if the car starts to bog, you found a leak.

If you need any Mazda parts, give me a call at 303-678-8950. My name's Domonic. I'm pretty sure we're the closest Mazda dealer to your now that Champion got shut down.

The other day got the car out to drive it and instead of RPM's going back and forth it did settle down however,... now it idles at 2000 RPM's havent gotten around to checking it, been to damn busy working. Hopefully here soon can go through it and check everything out.

Thanks Domonic, I will keep your number handy!

crazygsps wrote:The other day got the car out to drive it and instead of RPM's going back and forth it did settle down however,... now it idles at 2000 RPM's havent gotten around to checking it, been to damn busy working. Hopefully here soon can go through it and check everything out.

So it did that without making any changes? If that is the case then I bet you probably have a vacuum leak, etc. like chickenwafer said.

Yea I havent even started anything yet on the car and it started idling at 2000 RPMs. I'll look around and start checking stuff hopefully this week whem I finally get some tim eoff from this job of mine.

Is your car efi or is it carbureted? The induction system makes a difference when it's time to trouble shoot. But I have to agree with the likelyhood of it being a vacuum leak.

Carbureted

Hey Dominic were do you work i might need some parts
thanks