Gas Mileage?!?! Am I Alone?

[Adjuster]

To Vegas and back to Boise this October, averaged 25.5mpg.

This was with a week of Vegas traffic in the mix, drag races, crusie and other full out running thrown in there. (And a ticket for 80 in a 70 when I was really going 89 at the time, but had been going 120mph....)

Quite a bit of running at 3 digits on the way there and back. Perhaps 300 miles of it.

Engine is tuned right for AF's on boost, and at all other times the O2 sensor and TCCS keep it right at 14.7 or close to it. No lean running.

Around town I'm happy to see anything better than 12mpg. (Less if your really boosting.)

Over 400rwhp and 470rwtq on this motor.


I would check the following.
02 sensor. I'm guessing yours is not working right. The TCCS falls back to a map that is rich all the time, so your fuel economy sucks, but it runs and does not harm your engine.

If you have any type if fuel mangement, make sure your not bumping it fully rich at part throttle settings. (Off boost basicly.) This will cause your rich condition too.

My first guess is still the 02 sensor. (Get one from MCD, he's got great stock type ones for an awesome price, the only thing is the plug is wrong, but nothing that few moments with a soldering iron and some shrink tube will not fix.) The wires are actually longer than stock, so you have plenty of wire and heat shield to work with. Pull the heat shield back, and secure it with a clamp or some tape so you can solder the wires without it in the way. Then when you remove the clamp/tape it will extend back over the area you did the spices at, and cover it up from heat.

 

[Jspec7m88]

Adjuster:

No, it's not my 02 sensor. When I first bought the car, it was getting around 22mpg highway and 15-16 easy city driving...i've owned the car for a while now and i've dumped stupid amounts of money into it since i got the car...i've noticed "specifically" that the mpg has been dropping...i'm assuming this is all because of performance...i've had ALL internal work done...turbo was rebuilt by HKS, cam gears, camshafts, everything...so i'm just going to assume that its just the hp...but with the 02 sensor, i replaced it w/ the best i could find, and its worked fine...all my readings show that its good. not lean, not rich.

 

[Joel W.]

it sounds to me like your cat converter is plugged possibly??.. something to check... dont think any one mentioned it yet?

 

[Jspec7m88]

i dont have a cat. converter. all 3" from the turbo back.

 

[Fuzz420]

You can try this it works for my city milage. At a stoplight when taking off i try to take off with the least throttle as possible. I try to shift each gear no higher than 2500.It doesnt seem like much but when i shift "faster" for the next gear while keeping my rpms in this range im able to keep a good acceleration speed to where i dont piss off the people behind me,but yet get the best gas milage possible.

 

[aljordan]

I'm suuure I'm more modded than you. I get 21.5 on average. I thought that was low, so I dropped in a new o2 sensor. I don't think mileage has cahnged much since doing so.

Something is wrong with the car to get less than 10. Unless its on a track and you're WOT for most of that tack.

 

[viperjames]

how much does it usually cost to fill ur beasts.. how how many miles can u get before you have to fill again
city and highway

 

[Jspec7m88]

aljordan...so exactly what do you have done to your car? dyno? 1/4 mile? let me know...i'd like to know.

 

[GreenChevelleSS]

I just checked last night and I got 11.3MPG. I think I can get better than that in my big block chevelle with 4:10 Rear.
Im gonna get my Cats removed pretty soon and thinking about getting a new O2 Sensor, About how much do new O2's cost?

 

[Justin]

down to livermore cali from spokane washington - 31 MPG.

City ~25


Intake, Exhaust, Profec e01.

 

[JustAnotherVictim]

I'm in the 20mpg range. I'll have to do an actual measurement sometime

 

[casper35404]

I was amazed that I got 30MPG on a 3 1/2 hour trip on the interstate at an almost constant 70MPH with a few 85MPHs mixed in.

 

[NDBoost]

13.43mpg

210miles on 15-16 gals of 91 octane..

mostly city driving, with new o2 sensor, no cats, new plugs and wires, refer to sig for mods.

 

[MDCmotorsports]

tomjan87...it runs great. perfect...boosting about 13lbs right now...bored out, ported turbo elbow, cam gears, camshafts, i have ALL the goodies...unfortunately, do to shytty tires...i only ran a 13.76. but we all know that supra's have a lot of top end...so...yea. but no, back to subject, everything is great. it is of course getting really cold now here in indiana and since it started getting really cold, its been in the 9's range of mpg...but when it was warmer...it was around 13-14...i dunno man. i still love it tho haha

Wait a minute....

You're complaining about gas mileage, and yet you haven't told any one yet about your rod knock?

For the record, I get 240-265 on a tank of gas.

 

[Jspec7m88]

i believe i've been involved in several posts talking about rod knock! besides..i'm sure i made that comment when I didn't have it .

 

[suprajjang]

you shouldnt complain i get 12mpg no matter how easy i drive the car:icon_evil i have tried everything to fix it but i finally just gave up becasue i keep spending more and more money but it doesnt improve at all:icon_evil

 

[Jspec7m88]

well the only time my gas mileage goes up...its when it's interstate driving(obviously)...which I'm in the city almost all the time(dont want to drive fast because of rod knock)...well to the gauge, i'm gettin 8.7 and it stays there...acouple times its went to 8.8 BUT...i'll see what happens once I fix my RK.

 

[NDBoost]

you shouldnt complain i get 12mpg no matter how easy i drive the car:icon_evil i have tried everything to fix it but i finally just gave up becasue i keep spending more and more money but it doesnt improve at all:icon_evil

i know how you feel :3d_frown: $40 set of plugs $80 set of plug wires $60 o2 sensor and still no better gas mileage

 

[Caplax40]

I get mid 20's without the A/C going and about 16 with it on. That's mixed city/highway driving, for an '89 Turbo Automatic.

 

[grsupra87]

I get 20 with a heavy foot. I have gotten 24 before. I am N/A 5 speed with 4.30's. I always fill up at half tank, and get 200 to 230 out of the half. Only mods are 3" custom exhaust (still have cat for now) with Ractive muffler and FIPK.