My car's running way rich, I'm getting about 12mpg.

Everyone's been telling me "Check the fuel injector!"

I checked out the intake, filter and all that junk, but I'm not sure where the fuel injector is.

Is this it? If so, it doesn't move at all during revving, what's it supposed to be doing?



And I think the problem may be with my fuel injectors, any opinions on fuel-additive to try cleaning them out?

 

Go to the FAQS and look at the Factory Service Manual or go get a Haynes manual. Good to have in general and it'll tell you all you need to know. The injectors are under the intake manifold. Running rich on a stock system.....oxygen sensor, bad airflow meter, vacuum leak, ummm....yeah that'll get you started.

GET A SERVICE MANUAL!!! It'll help alot in the future.

 

That`s a pretty wide open question. I would grab the Full Service Manual (FSM) and read the FAQ and start troubleshooting. This site is full of info, but a not-very-specific question will not, can not get answered. Have fun inverstigating, you can do it! And remember, the car is YOUR bitch, not the other way around.

 

That's right! Rebuild your motor before it rebuilds you, lol. Seriously though, if you take care of these cars they'll be more than happy to show you their wild side, WOO!

 

Edit*

Everyone keeps telling me to check out the air injector, and I have no idea where THAT is. I looked it up though in my haynes and I have a pretty good idea now. Gonna check out the vacuum tubes and such tomorrow if the weather's nice.

 

See www.toptiergas.com for a list of good brands of gas, and you won't ever need fuel injector cleaner. But if you really want to clean your injectors then have a shop do it. I bet that's not it though. Like people said check the vacuum lines, etc. first.

 

FYI: That's a Double Throttle Diaphram in your picture. The upper item. TPS the lower. Not your problem.

 

Is the double throttle diaphragm only supposed to be on automatic tranny cars? searched it and found only threads about auto trannys w/ it. What exactly does it do? When I push it in it doesn't make a difference in engine sound or anything.

How should I check the vacuum lines? My school's auto shop teacher is ASE certified in a hole bunch of things, I'm gonna take a look at it with him tomorrow probably, but could I just pull the vacuum liines off and make sure that they're clear? And is there a certain tool used to check the air flow meter, or could my shop teacher tell me if that's in good working order?


I'm going to check my compression tomorrow too, to make sure that my engine's not pooping out on me. It's supposedly a street port rebuild w/ (600 now) miles on it, and it's pretty responsive but it doesn't run like a champ, will performance improve when I get the air/fuel ratio correct?

 

Your engine is street ported? That changes everything. Street ports enable the rotary to breath better, therefore using more fuel to make more horsepower. The driver is more likely to drive with a performance 'attitude', 'cause it's more more fun.

You may have no problem. The EPA estimate for city driving is only 17; few people achieve that number.

Keep in mind, the rotary has never been nor will it ever be noted for it's fuel economy. Stock, they DO run rich. It is just the nature of the beast.

On my S5 Vert, I can easily get down to 12 mpg if I drive mostly in town and suburban driving AND I drive it like a performance car. If I really baby it, I can get 16-18 mpg city.

Just make sure you have new plugs, wires and air filter. Use that top tier gas. Check for obvious faults, but if the plugs don't look black, you are probably ok.

Good Luck!


EDIT: Just for kicks, put a bottle of Techron in the tank for a couple of tankfuls. This does a great job of cleaning fuel injectors. I have seen it restore a completely stumbling-nearly-cannot-run car with proven clogged injectors to smooth operation.

 

Ohhhhh.... yea man, streetport will kill your MPG..... and yea, if you are running rich, you are losing horsepower, however with a streetport you will need more fuel than stock because you are getting more air than stock, get a s-afc or a rtek and tune up, then you should be ok! And BTW, don't be shocked if the compression numbers are low at only 600 miles are on a rebuild, hell you've still got a few hundred to go before you are broken in!

 

They all have a double throttle diaphram. It's for cold engines. Keeps the secondary plates closed and becomes disabled (double throttle diaphram) once the engine is warmed up.

 

This sort of info is a lot of help when trying to et a diagnosis from us forum people. Just for future refrence. You're not going to idle quite right either with the port job.

 

Haha, sorry I didn't post that earlier guys. I know that having a street ported engine takes more fuel than a stock port one, but my exhaust constantly reeks of gasoline. Makes me feel a little better about my MPG though jackhild. I'll change my lines and plugs and all that, check the vacuum lines and air flow meter and get the fluids changed this weekend and probably swap out the O2 sensor, then update you guys on how it's doing.

 

Any port that can be considered a street port will have very little effect on mileage. The average street port done on this forum won't negatively effect mileage and in some cases may increase it.

Now if you drive with your foot in it all the time, that's a different story.

It's likely that the car just needs a tuneup.

If the car has high mileage and the injectors have never been serviced, have them professionally cleaned. Test the ECT while you are there and make sure it's reading correctly.

 

if your exhaust reeks of gasoline smell, maybe your catalytic converter is clogged.

 

I had the exact same problem you did, though no streetport. What finally increased my mileage significantly was replacing the thermostat. It was stuck and causing the engine to "warm up" all the time.

It costs 12 bucks for a new thermostat and it took me from getting an average of 11-12mpg up to 16mpg.

I highly suggest you change the thermostat and see what that does for you.