89 rx7 goes from start to redline
 

Ok so here's the deal. Every time I start my 89 rx7 non turbo it goes immediately to full throttle...at least it seems...screaming to redline before i have to shut it down. It seems to be running smooth enough, but I can leave it running long enough to really tell. Anyone have any ideas?

check your throttle cable and your plates in your throttle body to make sure they are free and not being yanked wide open.

And make sure the cone on the AFM is not stuck in the fully depressed state.

Ok thanks guys. I will give it a shot!

Definitely sounds like a throttle cable issue..

What is the vacuum operated part in the picture called?

Sent from my Verizon Wireless 4G LTE smartphone

You need to be less vague but rather more specific. If you need to rely on a close up pic then have at it.

The part directly above the radiator cap.

Double Throttle Diaphragm (looks like a small can with a right angled pipe coming from it that connects to a vacuum hose that runs towards the rear of the throttle body and connects to the white plastic nozzle called the thermovalve). Helps keep secondary throttle plates closed when the engine is cold. Could you perhaps provide a close up pic of the throttle linkage at the front of the throttle body? There is a lever in the horizontal position which rests upon the bottom of a short lengthed screw. It is directly in front of the black cap on top of the throttle body. The lever is part of the secondary plates. When idling it needs to be in the same position as it is in your pic. If it, the lever, drops down just a bit from contacting the screw the idle will increase greatly.

The picture above is not actually of my car. i removed that piece from my car because it was faulty and somehow misplaced it. i havent been able to find a replacement for it. here is what my car looks like.

In your pic the lever, which I speak of, is not in the horizontal position which means the secondary plates connected to the lever is causing these plates to be open when you start the car which will definitely cause the idle to zoom to extremely high levels. You need to rectify this issue and the idle will drop substantially.

thank you very much! from what ive read on here the double throttle system is not exactly necessary for operation. is that accurate?

No it isn't necessary, but even if it doesn't work when in the default position it still keeps the necessary throttle plates closed when idling, which is vitally important.

Thank you for the info. I'm going to get this puppy running! Correctly that is!

And you need to take care of the vacuum line as well. Normally, there is but one line to the diaphragm but it looks like for yours there are two lines, which likely means the car is/was an automatic as autos have two vacuum lines running to the diaphragm but a standard would only have one (thermovalve has 2 nipples if a standard and three if an auto).

My car is a manual, but the motor is a swap from a 91? I think. Very possibly an auto. Should I change that part out or is there anything else I should do?:scratch:

The white plastic thermovalve is a key tell as to whether it was from a standard or auto. All you need to do is make sure the lever I speak of is horizontal (and from the looks of it that screw is too long and keeps the lever from springing fully closed but it might just be the pic). The first pic provided illustates how it should look. Besides capping the vacuum line(s), you need to make sure you don't get on the throttle immediately after starting a cold engine and prevent from doing so until the engine has warmed sufficiently.

Ok thank you.

Ok i must not be looking at this right.....which lever?

Located at the front connected to the long spring. The lever rests against the bottom of a screw which is mounted through the throttle body.

After start goes straight to redline
 

Hey my name is Luis and I have a 1988 mazda Rx7 and when I start my car it shoots straight to redline