my '94 GC (mods in signiture) before the crank snout snapped off) averaged 21-23 mpg to tank (dividing miles to the amount of fuel required at fill up), beating the **** out of it, no i'm not some stupid ricer doing neutral drops, but i drive very aggressive acceleration wise, i love to fly around turns (which slaps the fuel in the tank around, & evaporates it) i'm always the first off a traffic light, lol

moms '00 GC Sport with a 3.3 (108K)(non flex) AirHog in stock cold air intake, straight only 2 light bends exhaust with a DynoMax UltraFlow, & stock straight thru resonator, new NGK G-Powers (platinum) & new AutoLite wires, & GoodYear Assurance triple tred tires which sucked up some gas, but are worth it! the computer generally stays in the upper 21 to lower 22 mpg range, & she drives aggresive sometimes when she needs to put a ricer in his spot, lol, oh I run Mobil 1 synthetic in hers also

-greg

 

I guess my 3.3L Flex Fuel is a gas hog. My best city trip so far -- 10.4 miles at 14.9 mpg (no A/C no traffic). If that's my best it's really sad, because everything about my van is beautiful - it's a totally decked out model.

I did a Live Data run on my Auterra OBD 2 computer reader - see the pic of my run.

It shows especially my engine rpm vs speed.

31 mph 1354 rpm
32 mph 1295 rpm
30 mph 1358 rpm

I will change oil with Mobil 1 and Mobil Clean 7500 and Slick 50.

I get my avg mpg readings from the overhead computer after a trip is run. But while I'm driving the instantaneous mpg goes into a good range over 20 mpg while cruising in the city in a good gear.

Some people mention NGK plugs - are they the best?

 

crap i just realized my sig doesn't have my mods listed

what i have done to my 203K '94 3.3 engine wise is;
-ported & milled heads
-short ram intake
-ported & reshaped exhaust manifolds
-gasket matched lower intake
-straight minimal bend (no cat) exhaust 2.5inch into 60mm with '02 Accord resonator (peforated core, not louvered, straight thru glasspack basically)

-breather filter
-rubber coated underside of intake (not sure if it holds heat & or helps insulate against it, lol)
-ported upper intake neck
-indexed NGK V-Power plugs
-stock wires (my mallorys tore apart)

thats all i can think of for now, i might be forgetting something


-greg

 

Hey Sport,

Have you checked the accuracy of your computer - miles driven divided by gallons burned?
Are you burning gasoline or E85? E85 mileage is much lower.

If you really are getting gasoline mileage that low, something is wrong. I would have it checked out.

Let us know when you figure it out.

 

my last fill was june 16th 65L pouring out the fill tube.... refilled june 21st 65L pouring out the tube.

according to the computer
distance traveled 652KMs of mixed driving
time driven 7 hrs and 49minutes
10.8L per 100 kms average cusumption

according to GPS highest speed attained 132kms per hr
average 88km/hr

just did synthetic switch and new champion stock platinum plugs.
tire psi 32.
no cross bars on roof rack.

A/C operation about 60% of the time
ussual high way cruising speed 115km/hr
currently in the process of moving 100kms away from where i currently live.
so the van has been loaded full for 50% of this fuel tank.

2001 GC ES AWD 3.8L

 

I will fill up with 87 octane Amoco on Saturday. Then I will drive and note the miles on my next refill to check my mileage against the accuracy of my overhead computer. If my overhead computer is inaccurate for mpg I don't know how to fix that - does anyone here know how to fix it? It would be good and bad news for me if my overhead computer is inaccurate (good if I get good mpg, bad if I have to fix my computer).

All my plugs are now Bosch Platinum 2's and my engine oil is Slick 50 + 2 qt Mobil 1 Extended + 1.5 qt Mobil Clean 7500. I hope my engine oil makes me get more mpg. My air filter is clean and tires are up to max pressure.

I bought my minivan knowing on a test drive it got bad mpg and the engine light was on. I thought it was a bad O2 sensor but after I checked everything and tuned it up I'm still getting bad mpg. Last drive was 5.8 miles at 12.0 mpg city driving. I thought after I tuned it up it would get good mpg.

I'm not ever going to use E85, as you have to use special engine oil for that.

My OBD 2 scanner does not show anything bad - tripped or pending codes - for my upstream O2 sensor. No trouble codes at all.

I looked at one of my recorded runs and half of my driving time is spent idling waiting for the light while driving in the city of Chicago, IL. See the pic. (But my old 95 GC 3.8 L wasn't bad). The pic also shows the values of both my O2 sensors.

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