1jztts

90k miles 1jzgte soarer.
I am getting 14-15mpg in the city without boosting. I've changed the plugs, air filter, passed smog with flying colors so 02 sensor is fine. Car runs great.
I've been chasing this problem for months, its so ****ing frustrating watching my fuel gauge plummet while going to the grocery store.
Any ideas?
I am going to change the fuel filter and fuel pump next.

ps Car is stock

shern

iTrader: (6)

Hate to say it, but why did you throw a 1JZ in there if you're concerned about gas mileage? Seems counter intuitive.

With that being said, I get 12-13mpg on my 1JZ around town. Full boost of course. That's why I have a 1JZ.

RyanV

iTrader: (9)

The AEM wideband needs to be on everyones swap list. It's an EXCELLENT diagnostic tool.

Part throttle cruising, idling or light acceleration, the 1JZ Ecu keeps the Air/Fuel ratio between 14.2-15.8m, which is perfectly stoich, not rich or lean...(I've verified this with 3 different Ecus on the same car- The auto trans Ecus lean out after everyshift and the manual trans Ecu is full rich after each shift.)

So, anytime my wideband reads any differently then 14.2-15.8, off boost I get curious.

I wouldn't change the fuel pump or fuel filter to fix this problem. I would replace the cheap Ecu coolant temp sensor before either of those.

I also get 22MPG combined driving on premium gas.

I would say something isn't right, but if your burning that much fuel when your not on boost you should see gas/smoke out the tailpipe. Your Ecu coolant temp sensor could be bad, or you could have a leaky injector. You might pull the plugs after it warm and smell each cylinder and shine a flashlight into each cylinder.

What does your oil look and smell like. If its really rich you can washdown a cylinder with gas and gas into oil also is a BIG problem as gas dilutes the oils protective qualities.

You might check for codes since it takes 1 min.

Without an AEM wideband hooked up, it's impossible to say if your fuel mixture is rich or lean.

megamax

iTrader: (9)

bump!!! iam getting 16mpg on the highway off boost. any ideas??

Vrank

iTrader: (4)

Wide band? What injectors/fuel management? I'd try fresh plugs.

turbodremz

iTrader: (18)

The MPG's that are being posted up sound about right to me.

Keep in mind your diff gearing has a role in this too. What are your rpm's at while highway cruising?

Also, these arent light weight cars. The 1JZ is a smaller displacement, so has to work a bit harder to move the car while out of boost. Remove some weight possibly?

You want good MPG's, do an LS1 swap with a T56 and leave it stock. My peak average so far is 30.9mpg:

Ali SC3

iTrader: (10)

if you have bypassed your charcoal canister also and let your car sit out on hot days, the gas will pretty much find its way out of your gas tank over time as well.