Bad mileage

I am pretty new to owning my ZX2. It’s a 01 and the mods that came with it that I know of are the K&N airfilter. It has been lowered, previously with a pathetic coil over set up. I took that off and replaced it with Eibach springs and KYB shocks. It has 17’s on it w/ 205/40ZR17 84W (not sure of the 84W) So any way I get about 200 - 215 miles out of a tank of gas. My previous car was slightly modded and I drove it harder and still eeked out over 300 miles to a tank. Any ideas of what could be causing the poor fuel economy? This is why I hate buying used but couldnt pass up on the deal. I have tried using nothing but premium gas but that just seems to waste my money.

latley my mileage has been about the same. I used to get around low to mid 30s but now have been low to mid 20s…dunno why

I get about 27-30 miles to the gallon on the average. I only hit over 30 miles to the gallon once since owning her. What kind of driving do you do mostly, city or highway? That can make all the difference right there. Have you tried putting fuel injection cleaner in your tank? That might help.
I will talk to my dad tonight to see what elso my cause poor gas mileage. He’s a parts pro at Advanced Auto Parts so he might have some other suggestions.


Thanks Miranda that would be a great help. I do a mixture of both city and highway driving. I do like to get on her alot…but then again I have always driven like that and have gotten better gas mileage in other cars. Im tired of getting SUV gas mileage. (15mpg) I got the car thinking I could get a little performance with my fuel economic car.

i would suggest the obvious, plugs,wires, air filter, pcv,check vac. lines, check and make sure there are no leaks on the intake, make sure there are no exhaust restrictions or leaks. all prety much normal maintenance things. tire size may have a little to do with it. you may actually be putting on more miles than the odom. says. there are no check engine lights–i hope. if the car runs hot it would use more gas.

just scann your ECU, maybe your O2 sensor or MAF are telling him to consume more gas less air.

I have done all the usual maintenance things, plugs, wires , etc that was my first guess. I don’t have a way to read the computer. I guess I should take it in or just go buy one.

** What is the easiest to use choice for a code scanner/reader. I see alot out there but really don’t know much about them. I would just prefer to put my $90 into one of these computers and not to the dealership.

i never bought a scanner either–most of my friends are mechanics and own their own businesses so i get to use them for free.they usually will run a diagnostic test for about 25-75 depending on the vehicle. however most of the major tool companies make them-- kinda pricey though–just scan the internet, get a good idea of what you want and need, and price shop accordingly.

oh and my car gets about 27- 30 mpg with a cel on (iac problems) so i think you should at least get about 300 per tank.

I have been shopping around and have found a few for a reasonable price. I don’t have a cel on so I have no idea what is wrong with it. It is just buggin the crap out of me. I was about to start ripping into the injectors to see if the previous owner changed them out and put in larger injectors. I don’t think he would have done that seeing as how there is still the stock exhaust and header on the car. Can’t really see any other upgrades engine wise than the K&N.

this may sound stupid but about how many gallons are you putting in when you fill up. if your puttin in 10 gal when you fill up–yea your milage sucks. but if your only puttin in 7 gal–your milage is about normal. these cars are notorious for the fuel guages reading wrong when it gets below 1/2 tank.

Ha …that’s a little hard to get the exact on. I fill it up till she can’t hold no more, I run it to empty before filling up again and always reset the rip meter to gauge my mileage.

check it next time you fill up–if its like 7 gal and 210 miles–thats 30 mpg not too bad. if your guage is reading wrong you could still have a few gal. left in the tank. hell 5 gal could give you another 100 miles

Keep in mind that the fuel mixtures are being switched over from Winter to Summer additives.

This will probably affect your Gas milage some

I get around 35-37mpg.

I have not done a modified aftermarket CAI. Instead I did the resonator mod with 2.5" muffler tubing, has worked wonderfully with removing both resonators with a K&N Drop in to replace the stock.

My setup has been…

Resonator mod
Ford racing wires
Plenty dielectric compound
35psi in my tires
Gutted trunk with slightly gutted behind dash and glove box for weight…
Ford Racing UDP with gatorback
Getting ready to do a/c elimination…

No sense in listing my suspension mods as that has nothing to do with mileage… but…

Anyway… that has helped my mileage quite a bit. At first I did it for power… but… meh, bike has interested me more… so I drive and keep it at about 68-70mph at roughly 3000 rpms and pretty much barely even am touching the gas. Has been at about 35-37mpg.

I’d check a diagnostic and see if you have anything funky going on.

(EDIT) BTW these gas meters lie like a bitch.

I’ve got some fairly extensive mods done (standard bolt-ons at least) plus rims ‘n’ tires (205/40-R17) and I’m still averaging about 30mpg with city and highway driving.

  • Darron

OK so one thing I didnt do …I didn’t replace the coil pack. I have not been able to find one that is above stock. Looks like MSD and Accel stopped making perfomance coils at the 98 model year. Any ideas?

stay with the stock one it seems to be the best

hey Brenden both MSD and Accel make coilpacks for the z after '98. I picked up my Accel at my local Advance Auto Parts. They did have trouble finding it on their computer tho.

My coil pack went and I don’t remember my mpg going down when that happened. Its worth a shot though I guess.
My dad suggested the same things that these guys did so I hope you find out what the problem is. Good luck Brenden.


Hey redairzx2 - can you get me a part # off your coil pack? My parts person wants to get that so they can update their info. Thanks