Only 10 mpg?
 

I have a 87 tii, and I get horrid mpg. I’ll post the mod list, then more detail

New 720cc secondary injectors, new 550 cc primary’s
rtek 1.7
walabro 255
aeromotive fpr at 40 psi
apexi neo running off boost pressure
racing beat rev tii exhaust
stock port, 1400 mile engine
new fuel filter

afr cruising bounces between 14.3-16.
under boost, afr is 10

city driving with boost I get 10 mpg, hwy without touching boost is 17

also I notice I am not using oil which scares me, I haven’t tested to see if the omp is working, but the gas also smells like fuel, I’ll get a taste test soon. Also when starting while hot, I’m pretty sure it floods one of the rotors and makes it so it runs on one until it clears it up.

Also have a new o2 sensor for the ecu.
I do have a slight fuel leak out the tank (never puddles)

Welcome to the wonderful world of rotaries!

Lol fuel economy is not a strong suit with our engines. My 88 NA gets average of 12 mpg. I don't think you have an issue.

Also I would hope your gas smells like fuel...
I assume that since you're concerned about the lack of oil consumption that you still have your OMP. Do you premix?

lol I meant oil smells like gas. Yea I premix .5oz per gallon.

I can't speak to OPs turbo, but your NA should absolutely be getting more than 12 MPG. Unless you're always at WOT and shifting at 7k. I get 20-26 in a tank of normal driving + a few spirited drives.

Also for some reason I run lean in first, and the car bucks.

Your oil may be going through the omp and functioning properly. The fuel in oil is probably mainly from blow by.
I’ve noticed this on my car as I do not run the omp, my oil will smell of fuel, and the oil level rises. My car is now mainly track only and sees 5k+ rpm most it’s lifetime.

I used to daily my t2, and when people ask me what the gas mileage in my rx7 is, I just tell them I put gas in it when it gets low so I can’t comment on mpg.

You should be getting better gas mileage than that. How's your TPS?

I just came back from a 3-day road trip to the Shenandoah region of VA (Harrisonburg) for fly fishing school. It was about 135 miles one-way from the DC area. Initial fill was mixed interstate and city, and final fill was straight interstate. On both fills, I filled until the gas overflowed the filler tube. I had the cruise set at 70 mph for most of the interstate drive. I've got 18.1 mpg on the first fill and 28.3 mpg on the second fill. I've got mainly stock S5 non-turbo with RB catback and high flow cat with a 4.3 rear end with 0.756 (GTUs) 5th gear.

unless youre driving in boost all the time it should be getting much better. If I drove my NA like a normal person I averaged 17-18MPG and I was able to hypermile the NA up to 27mpg. (confirmed 24mpg with traffic going back the opposite from the trip)
Keep the RPMs down, dont listen to the youtube hype of always being over 3-4k rpm. I usually put around town shifting at 3 and letting it cruise around at 2200-2700. I obviously shift if it gets bogged down from a hill.

both of you guys (Stussy and Cardinell) have issues if those numbers are under normal driving conditions.

this is more a thought than advice because i don't fully know the ins and outs of the Rtek and how it works. i'm under the impression that it's adjustable, so my question is have you re-adjusted it since the rebuild?

depending on the rtek it can be non adjustable, like mine. Stuck with its current map. I am wondering if this is the issue. I also lean out under low load throttle, but super rich under boost. Went on a long drive on the Interstate and got 18 mpg tho

I am getting around 16-17 on E85 when not in boost. S5 6 port Turbo on a Haltech. When I'm running 93 octane I can get 22mpg on the highway. I would certainly look into a tune up for your cars.

-M

poor fuel economy may be an incorrectly set CAS

very well could be, I know I have it on the right tooth, but idk if I have the timing perfect, does anyone know how I would time it if I can get an idle only to 1000 rpm, can’t get an idle at 750-850

its been a long time but there is a green connector on the harness i believe you can jump it out to lock the timing...

https://www.rx7club.com/new-member-r...timing-879097/

forgive my ignorance, what is locking the timing, what does it do? From that reading, does it make it so the ecu doesn’t advance the timing, therefore it should line up with the mark at any rpm?

Not exactly sure what you're asking, but grounding the green 1-pin connector (which is next to the battery box) disables the BAC. With the BAC is disabled, you'll get the lowest idle. Also, turn-off any accessories.

It's the two pin green connector by the leading coils. The FSM calls this the "initial set connector" and it's used to set idle speed, timing, mixture, etc.

You can use a paperclip as a jumper. Just remember to remove it after you're done, or timing will be locked at base.

Oh, you're right. Didn't notice that he has an S4. The S4's have a two pin green connector that you jumper the two pins together. The S5's have the one pin connector that you ground.

you need to lock timing so that you can use a timing light to verify it is set properly. otherwise as it attempted to idle it will wander and you never get a stable number as it adjusts