Copy, paste, add to signature.

 

I'll give it one more try.
Won't even look at the gas gauge and will drive normally like I would rive my Honda or Acura.

BTW you are from Worchester! Finally someone close enough on big and stable enough miata forum

 

Did somebody say, "Very low gas mileage?!"

 

im doing 12.7 in my miata

 

I understand that the plugs don't agree but I just listed the types of problems that would lead to terrible mileage. If an o-ring was broken and it was spraying fuel from the rail it woildn't show at the plugs and he may not smell it. This happened to me when I put my new injectors in but I had a wideband and immediately found the problem.

OP, if you are driving your miata at super low rpms it is going to get terrible gas mileage. You are loading up the engine like crazy and it is dumping fuel. As stated earlier it is much happier between 3.5k and 4.5k.

 

Have you checked your tire pressures?

 

Will do!

Anyways, I started driving it normal shifting between 3 and 4.
Forgot to mention this earlier My car is also idles weird when cold. The gauge might already get to the normal temp but rpms stay at around 2.3k and if I press the brakes it goes up and down from 1.5-2k

Once the warms up everything is normal

 

I'd check the temp sensor. Not the one that goes to the gauge, but the one for the ecu. If the ecu thinks the engine is cold, it'll run overly rich.

--Ferdi

 

Where exactly is it located?

 

Found it. I will be doing CAS-0 ring job one of these days, and will adress the temp sensor as well since it's all back there

 

Those plugs look fine. I will repeat, fill the tank full, drive 60 miles, refill tank.

Example
Lets see I drove 62 miles, and when I went to fill up I used 1.8 gallons. I take 62 and divide by 1.8 and I get 34.44444444444444444444444444444444444444444444444

The best part of this test is its free, ie you will use the gas anyways. If you have a brain annurism? from the calculations and have to go to the hospital then that will cost you I guess.

 

"Too Funny" Jacob

Anyways So Far I drove 140 miles on 12 gallons, gauge is pretty much lined up with the E mark.

Local Mivec Enthusiast suggested that gas station use winter blend gas this season (as well as other winters). Not exactly sure what it means or what they change in petrol anyway it's not diesel which may freeze. Might that be the case?

I was driving normally, shifting between 3-4 as suggested

 

Always better to take a sample of a bigger loop than a small one. AKA a full tank is better than filling up 1 gallon. The reason for that is not all pumps click exactly at the same amount of gas inside the tank. There could be as much as a half a gallon of difference. Some click early, others click late. Same pumps can behaves differently especially if someone topped off their tank before and filled up the pressure sensing unit or whatever you call it. Some will turn off differently based on the angle of the handle into the tank.

That said the 34 mpg number is a meaningless number because the possible error is so large.

 

This is what i did. I had oil comsumption and bad gas mileage aswell. 1) I cleaned my injectors and replace the injector orings. A real injector flush, not a upper plenium cleaning. 2) replacd my 02 sensor. It was lazy. 3) for the oil consumption i replace the valve guide seals.

 

While your plugs don't indicate running rich, IF YOU WERE actually dumping that much fuel into your engine you would surely smell it in your tailpipe. Start your car and let it get up to temperature. After it is warm, place your hand in the exhaust stream for 30 seconds... Walk inside and let your wife smell it. Serious (kinda).

If she smells heavy gas smell then one way or another that gas is passing through your engine. I imagine this would also be accompanied by black smoke on acceleration? If your car isn't passing that unburnt gasoline through your engine than your gas has to be going somewhere.

Buy some gasoline safe UV dye and place it in your tank before you fill up next time. Drive about 50 miles and put it in your dark garage on jackstands and use a UV light to look for leaks. That should give you a good idea where your gas is going.

 

Do you let the car warm up before you drive or do get in and go?

 

Put in a new Thermostat. I had a 160F and found when it's 30F out the car didn't warm up enough, killed my gas mileage and threw a O2/Cat code. I've replaced it with a 180F. NAPA $6.