I just picked up an 87' RX7 non-turbo with the 13B engine. I filled up the tank the other day and am now at 3/4 tank. Ive gone 30 miles. I did the math with the tank being 16 gallons and came up with 7 mpg. That seems very low to me. I understand this is a sports car but i would expect maybe 20's on a good day. I haven't been driving her hard, racing or rallying it around. Anyone have any ideas on what i can do so she will have some better mileage? If it counts for anything this is a British spec car.

This is the 2nd RX ive owned but the last one got fair mileage compared to this.

Thanks for any help.
Andy

 

Mine was a leaking pulsation damper... or so I think, I still haven't got it fixed but I'm pretty sure thats why I'm getting about 13 mpg

 

I was talking with an RX shop and he mentioned the thermostat may be bad. Due to the fact the temp gauge never goes past 1/4th. He said it would cause the ECU to think the engine is still cold thus giving it more fuel.

Im gonna pull it tomorrow and test it.

 

If I remember correctly on S4 1/4 on the temp gauge is normal operating temperature, on the S5 1/2 is the norm. Since you have S4 the reading appears to be normal.

 

it shouldn't go past 1/4 - 1/3 if it does your car might be overheating and causing alot of damage. I wouldn't trust that rx shop... however that being said, you should probably change yout t-stat if it is of unknown condition.

 

Well, if your car didn't caught fire, you're one lucky sob.

 

Well, usually, bad gas mileage is caused by clooged fuel filter, dirty air filter and such. When was the last time you did a tune up? Is a fuel line leaking? What did you check?

 

Is your O2 sensor hooked up? I believe people have noticed horrible mpg without the O2 sensor hooked up.

 

Ok here it goes everything i know about this car. I picked it up a week ago. Shes got roughly 74k on the clock. So far i have checked the vacuum lines, which all appear to be in order. I pulled the cap and rotor and cleaned them up he best i could along with the plugs. The air filter was a lil dirty but not to bad. As for any fuel leaks i have not noticed any in the engine compartment, though im throwing here on a lift tomorrow for a better look. As for the O2 sensor and fuel filter, where are they located on these cars?

Other small problems i noticed. upon start up a small bit of blue smoke comes out of the exhaust, from what ive read thats normal. When shes cold it has a problem idling it will got to 3k for a moment then drops to roughly 800 from there it surges from 800 to a few hundred rpm. Once warmed up it idles at 800.


Thanks for the help so far

Andy

 

The first step is a full tuneup. Cleaning a distributer or plugs won't work. Once the surfaces are etched or a plug is worn out, it must be replaced.

Surging idle is normally causd by a bad or misadjusted TPS.

The O2 sensor won't make much of a difference.

Leaking/dirty injectors are another common cause of poor mileage.

 

My bad here everything that has been said was in the sticky on the top of the page. Normally i never look at those.

So kinda on topic here are UK spec RX's the same as US spec? If so im ordering the parts from the states. I got some quotes for tune up parts today. Im not paying that much.

Rotor: 75 Pounds about $150
Cap: 30 pounds about $60
Plugs: 24 pounds about $50
at that point I left the store.

Some one kill me

 

You gotta pay to play

 

That's definitely not how you should measure gas mileage.

1. Fill up the tank until the pump auto shuts off.
2. Write down mileage.
3. Drive a bunch.
4. Fill up the tank until the pump auto shuts off.
5. Write down mileage.
6. (New mileage - old mileage) / gallons

 

Don't trust the gauge when its at the top either!!

On my '86 GXL, the top 1/4 of the gauge only gets me 50mi on a mixed tank, but then it slows down and I end up with ~250 on the tank mixed (20mpg/tank usually; i don't run it dry )

Just something to think about.

Edit: Beaten like a redheaded stepchild by My5ABaby

 

1. Glad you noticed the FAQ. ~24mpg if you're just cruising on the freeway is normal. Driving style can lower it some, but not nearly as much as you're talking about.
2. Fuel gauge is innacurate, don't rely on it. Especially since you only drove 30 miles. Record total gas from multiple gas fillups to full. Record miles driven. Divide.
3. Do a full tune-up regardless of whether or not you currently have any problems with anything. Get owners manual / Haynes manual / FSM (download in FAQ). Do every maintenance item. Repeat each item at certain times in future, according to schedule shown. This is true for any used car. Also for a rotary: Checking your coolant level and oil level frequently and immediately pulling to the side of the road before overheating are extra important. An OEM thermostat and other cooling system maintenance is also important. Also replace your oil plug crush washer (preferably) and properly tighten your oil plug after each oil change (just so it won't fall out; no need to muscle it). With a rotary, if you drive without coolant or oil for several minutes, your engine is toast.