21.5 mpg with ZE. What to do?

[OutlaW]

I made the conversions, and my car makes 20 mpg ... mixed driving ... city drive ...

[MazdaManiacMx3]

I think if my mileage was that far off from norm.. I'd try swapping out VAF's. Or at least check the shop manual and see if there is a test you can do on the VAF. My gut says that the VAF is telling the ECU there is more air present than there is so the ECU is juicing more fuel because of the erroneous reading. Dunno if this is correct or not.. but something to check if you can.

Tunes67

True , MAF's you run into the same problems , You should see the difference MAF cleaner makes on a car with a dirty MAF , try a new VAF and see if it makes a difference , New 02's and A Fuel filter isn't a bad idea anyways.

Kris-

[Whisper]

I changed the fuel filter, and I think my mileage went DOWN, and not UP. WTF?

I don't think I'm leaking fuel or anything... Although it's hard to check.

I'll try to find a different VAF.

[maryus]

Guys , what about 30 L / 150 km

or 42L / 270 km , my last calculation. cool eh ?

[Whisper]

Hmm, ok, upon further observations I guess it didn't go down, I'm still getting roughly the same mileage of 21.5 mpg, but it hasn't improved, either. Can't squeeze out any more miles out of it no matter how gently I drive.

[hgallegos915]

thats what i get turboed.. HOWEVER


i remember in my old tired k8, it was around 21- 23.. maybe its normal?

but considering you have a ze

Check codes.. thats the only thing to do..

could be a bad ecu.

make sure your ecu has no codes, get rid of the egr codes by just connecting the sensors without the vac lines(if you have a usdm ecu)



clogged fuel filter, sticking brekepads, bad driving, bad o2 sesors, bad knock sensor, (ecu being in limp mode), propper tune ups.

hmm cant think of anything else..

[Tunes67]

Whisper - are you running a CAI? If so.. what diameter piping are you using?

Tunes67

[fowljesse]

After you do whatever mechanical stuff you're going to do, try using 2 3/4 ounces of Acetone per tank of gas. It lowers the surface tension of the gas molecule, so it atomizes better, and is burned more thoroughly, which also improves emissions. I've seen about 4 to 6 MPG increase in my GS, 33 foot RV, V8 Mercedes, girlfriend's Toyota Celica, and am tracking the mileage increase in my ZE. Also, it increases octane, so you can use lower octane gas, and save even more. I have studied increasing gas mileage, and got my 15 MPG 3/4 ton Chevy van up to 21 MPG, while increasing performance. If you want to improve it alot, I may be able to help.

[Whisper]

hgallegos:

I don't think I have any codes aside from the CTS, which there's nothing to be done about, since I'm a 2-sensor 94 with a Probinator. Before the swap I've gotten 24-28 mpg on my K8, with the same VAF and ECU, so those should be fine. EGR is hooked up, though, and allegedly functioning. Brakes don't seem to be sticking. New O2 sensor and new fuel filter. I used to have a code for knock sensor, but it was kind of on and off, and it's no longer there after I chipped the ECU. The car is tuned up.

Tunes:

I'm running the Integra CAI piping with K&N filter. 2.5" I think, innit?

Couple things I'm not sure about: There's a hissing sound that gets louder about a second after I let off the gas (sounds like a blow-off valve, but I don't have a turbo). Checked for exhaust leaks, and didn't find any. Could be EGR related? Or maybe just the flow of gasses in the exhaust piping. And the other thing is the car slows down quite a bit as the engine revs down as I'm off the gas. It's not brakes sticking, since it doesn't happen when I'm coasting in neutral, only happens in gear. Feels like the engine slows the car down more than it should, especially if the car is not warmed up. Donno, if that's related to anything or possibly causing me to be on the throttle more hence using more gas.

[Tunes67]

I have a theory about the CAI intake tubing.. its a theory only and I have no proof to back it up. But.. I think when we reduce the size of the intake tubing to a smaller diameter than the internal diameter of the VAF.. That we are increasing the air velocity through the VAF. Thing is.. we arent getting MORE air.. its just moving faster through the VAF. This would result in the VAF Plunger moving further than it normally would if the air velocity were like stock. If the plunger is moving farther.. I think the ECU dumps more fuel to compensate for what it believes is more air flow. The internal diameter of the JE50 VAF is 3 inches. I dont have a ZE to compare with.. but I ran 3 in piping and couplers reducing down to the 2.75 only at the throttle body. And with my K8 setup.. winter mileage is 28-30 mpg average.

The more I look at this thread.. the more I think you have several things contributing to your lower gas mileage. Might even consider replacing your fuel pressure regulator as well. Just a couple more things to chew on. Cheers

Tunes67

[Whisper]

Hmm, if the speed of air is increased and the plunger is open more then a greater volume of air should be coming in. If the speed of air is higher, but the volume stays the same, it seems the plunger shouldn't open any more than it does with stock piping. I'm not a physics guy, so I might be wrong.

[Mnemonic]

its your flux capacitor or the fact klze's like fuel