Really Poor Fuel Economy

[DJ]

I use to think my mx-3 was bad on gas at first until I paid attention to the liters I was putting in. I use to think I was getting like 300km -350 to a tank of gas because it would be down near the E by that point. But I realized when I was filling it back up it was only like 30 or so liters until it was full again. Even at around empty it still had 20 liters left in their (50 liter gas tank). So I just started to run it to the E a lot more and I get around 400km to tank or so of normal but mainly aggressive driving.
Over the last 3 tanks of gas I figured it out by keeping track of the mileage and amount of gas going back in to it getting an average of 30MPG which is decent considering most of that is "spirited" driving.
Most I have ever gotten was 500KM, which was pure highway driving only cruising around 120kph. Haha, wasn’t sure if I was going to make it home so I was using the momentum of hills to my advantage.

Btw, because the owner’s manual recommends at least 91 octane, the original owner from day one has been running it on that, and since I have had it, I continued doing the same. Does everyone else run at least 91 in the K8?

[schuttie2002]

I always use 89. I dont know why there is that big of a difference in our gas mileage. I know my car is running spot on with fuel delivery. I take very maticulus care of everything under the hood though to make sure im running right though. I change plugs more then most do im sure, and Ive done a disty cap twice in the 30k miles ive owned it. I also have new plug wires, n use injector cleaner every now and again. I also have replaced one injector bc it went bad. Yea O2 sensors are like new in my car as well, plus I put a new fuel filter in it when i got it, n now again with the engine swap.

I dont see why I shouldnt get good milege. The owners manual says you can get 25-30, and Im right there. Also the probe advertised 23-28 mpg, and mx3's are like 400 lb less then probes, so i think that would justify the engine working less hard and getting better mileage.

One last though, I NEVER USE AC, EVER.

Good luck tuning up your car and I hope it gets the good mileage it should

[Juans_93_MX3]

I put 87 Octange in mine
I guess I can go higher

[glow]

I use to put 89 and went down to 87 after reading a few posts w/ ppl saying they had no problems running 87 and that it was fine to.

I couldn't find in the manual where it says you should put 91 or any specific grade (i checked the mx-3.com online manual)

[DJ]

I couldn't find in the manual where it says you should put 91 or any specific grade (i checked the mx-3.com online manual)

In the owners manual, not the shop manual. Next time i'm in my car ill get the page number. Mine's a 1994 if that matters, maybe they changed it a bit from year to year?

[Juans_93_MX3]

So how much do the oxygen sensors go for? How many are there again?

[Juans_93_MX3]

So how much do the oxygen sensors go for? How many are there again?

Also, one thing I have noticed is that my exhaust smells bad. It kind of smells like some fuel isnt being burned or something.
I have smelled the exhaust on my bro's V6 Eclipse, on my other bro's 95 Mustang GT, my parents Toyota van and my sister's Corrola and none of those smell as bad as my exhaust... wel except on my bro's 95 Mustang at startup but after that its fine.
My car was able to pass emissions a few days ago so it cant be a cat.
Maybe its time for a tune up? What do you guys say?

Also, I am 100% sure its not a fuel line.

[Nd4SpdSe]

I think my O2 sensors were C$160 each

[glow]

I got a 94 GS as well, but I don't know where I put the owner's manual (or if it even came with one when I got it)

But thanks for letting me know that it states to give it 91, I might start going back to the good stuff if that's what the manual says

[dkguffe]

Here in denmark, fuel is probably better/cleaner than in the states, I think.

I ALWAYS run on 95 octane, and my driving pattern is always the same as well.

Everyday I go 50km on highway at 90mph, and then 40km at 50mph. this adds up to 180km a day, and I always fill up at just about 450km. the used amount of fuel deviates from 45liters to 37 liters. normally, its just about 41,5liters. highway speeds does the difference. just a little slower, and the eco goes up and so on. If I go 92oct, is worse, and if I go 98, its much better, but still its the cheapest to go 95oct.

I wonder if swapping to a KL-ZE would change this much or will stay the same (since I just go long distances all the time with only a few sudden accelerations)

/Brian Denmark

[Juans_93_MX3]

The book recommends to put 87 Octane on a 93 V6 (1.8L) MX3

[Chiggles]

I started filling the tank with 87 octane for the first little while after I bought my MX-3, but then realized about a month later that it didn't seem to like it. When I was on 87, if I went out on the highway doing more than 100km/h for a duration of at least 10 minutes, every time I came off the highway and got to where I was going, my CEL would come on for a few minutes. Checked the codes and pulled up EGR sensor warnings. Someone suggested that I run the car through with 91+ to clean out any excess carbon build-up and that it should do the trick. Turns out they were right. Ever since, I run at least 89 and have never had a CEL complaint yet.

[Juans_93_MX3]

So even thought the OWNERS MANUAL recommends 87 Octane, we should put 91 Octane in our cars???

[DJ]

So even thought the OWNERS MANUAL recommends 87 Octane, we should put 91 Octane in our cars???

By the sounds of it most people run 87 on the 1.8l V6 so you should be ok with that. What Chiggles is saying, is that you should try running 91 for a couple tanks to clear out the excess carbon build up.

I personally only run 91 in my car... mainly because the previous owner since new used 91. So I figured it runs awesome how it is and don't want to take a chance of messing stuff up seeing its been running at least 91 for 10 years.

Another tip is to maybe change your air filter if you haven't done that this year. That gained me a decent amount of extra KM even though when I took it out it didn’t really look very dirty. I just put a standard stock one back in, next time I might try a K&N which I believe is also washable, so it will eventually make up for the extra cost.

Btw, my gas mileage from the last couple tanks has gone down to 25MPG from 30mpg...only real change is that it has gotten a lot colder up here.

[Juans_93_MX3]

Wow, you guys are right, just filled my MX3 with 91 Octane and it runs better. Also, I have noticed better fuel economy aswell