Ok so this is a followup to my previous thread about my poor mileage and the process of doing a tuneup. Heres the old thread. https://www.rx7club.com/2nd-generation-specific-1986-1992-17/tune-up-how-do-my-plugs-look-667675/

So my mileage has still not improved so I'm trying to determine if my injectors are leaking. I pulled my plugs to do a quick check that my buddy suggested. These new plugs have less than 1,100 miles on them. I took two pictures of the rear trailing because it appeared the most different.

So what say everyone?

Front leading:



Front trailing:



Rear leading:



Rear trailing:

 

Still using the stock oil injection?
If so, they look just about right.

What kinda gasoline are you using?
The deposits are kinda heavy.
Do mostly stop-n-go driving?
Very little freeway?


-Ted

 

Yes I'm still using the oil injection.

I'm running 87.

I couldn't really classify it as mostly stop-n-go or freeway. Actually most would be freeway commuting 35 miles roundtrip 6 days a week. But I do a lot of city driving also.

My mechanic thinks that the injectors on the rear rotor are leaking because of the lighter color on the rear plugs than the front.

I'm getting really tired of getting 10-12mpg on a lame N/A .

Thanks for the help, -Lukas.

 

What brand of gasoline?

If it is leaking, it's leaking very little.
If it's leaking a lot, then the spark plug would be very black.


-Ted

 

I've been using Arco.

Hm ok. So I'm back to trying to figure out why my mileage sucks so much. Could it be a clogged cat? I've still got average performance for an NA.

I've replaced the plug wires, plugs, air filter, and the fuel filter is very new.

Again, thanks for the help Ted.

-Lukas

 

How about O2 sensor?
Bad O2 sensor could kill around 5mpg, and you're right in that ballpark...


-Ted

 

Already replaced it, I forgot to mention that. I've done resistance checks on my AFM and everything was in spec per the FSM.

Thanks, -Lukas

 

Don't use Arco gas....

Just for kicks, run a couple tanks of 76/Shell/Chevron, and see if mileage improves. My dad told me when he had his '87 sport back in the day, the couple times he put Arco in it, the car would barely start and would run like ****.

Just my 2c

 

I'm willing to try anything at this point. Next tank I'll throw some Shell in it.

Could I have a clogged catalytic convertor?

 

Yeah, try running some of the "top tier" brands like Shell / 76 / Chevron was also a suggestion.
ARCO is suspect.


Does the car run hotter than normal?
Does it lack power?


-Ted

 

I couldn't tell you if it runs hotter than normal. I've had the car for 2-3 months and its always had this problem.

Same thing with the power, this is my first RX-7 so I don't have anything to compare it to. But the power feels like I would expect. But I could be underestimating the car.

Want me to fly the car to Hawaii for you to look at Ted? :P