'87 rx7 getting 10mph city and highway. I imagine this has something to do with the reason my car is lacking half the power it should have. So my car is lacking a lot of power and gets 10mph. Anyone know what this sounds like? help please.

 

Something is wrong (obviously). Any wierd noises or unusual car behavior? (other than lack of power and bad mpg). Any idiot lights on? Check engine light?

When my turbo went out a few months ago I recall it making an unbearable "Nail on a chalkboard" noise and I lost all power once into full boost. It also turns out when I bought my fc it was in limp mode due to a number of issues not being resolved to by the PO... Your ECU could be in limp mode, where the ecu is just giving off signals that it knows will work instead of actually taking real signals from the car, but this is normally only if a sensor is bad or incorrectly wired. After replacing my O2 sensor (pre-cat), I found that most of my power had returned and the car felt normal again (ofcourse after replacing the fried turbocharger).

 

'87s don't have limp mode.

Injector failure is very common at this point as these cars get old. Pull each leading plug and examine them to determine if one rotor isn't firing. At the same time, crank the engine over and perform a compression test with your ear:

http://www.aaroncake.net/rx-7/blown.htm

The plug should look dark tan to almost black (depending on their age). A plug that is wet with fuel, or one that is disturbingly clean, points to the bad rotor. If compression checks out, have the injectors professionally serviced.

 

i get about 12 or 13 city, but all of a sudden i get close to 30 highway..... what is that about? my car costs 80 to fill up, and since gas is 4.20 a gallon (premium) it has about 20 gallon tank. so i get about 250ish to the tank. but on the highway it skyrockets. i do alot of in city, but everynow and then i drive to anchorage ( 50miles away, all highway) and back, and i can drive there and back like 4 times on a quarter tank. 5th gear = my best friend.

 

I get 15mpg with premix and no o2 sensor...lol I need to replace my o2 sensor

 

Because on the highway, the car can enter closed loop and operate in a steady, far more efficient state. Driving in the city is very inefficient.

Now, you may not have to run premium. Unless you have a turbo car with higher than stock boost, all RX-7s are spec'ed to run on regular old 87 (someone with an FD will have to confirm that for the 3rd gen).

 

Limp mode for sure, good luck fixing.

 

Is this true of a stock psi turbo 13b? Even at stock boost I can run 87?

 

THERE IS NO LIMP MODE ON AN '87!

S4s do not have limp mode.

On a stock TII at stock boost, you can run '87. It's in the owners manual. Only if you start modding the car and/or increasing boost should you move up to a higher octane.