[mobiuslogic]

Alrighty guys, this has been a cronic problem for me. I always get about 250 miles per gas tank (16 gallons, not the bigger 18). The only time I ever got more was 300 miles ONCE! Literally once. Next time I got 275 and the third was back down to 250. This is only city driving. On the highway I can get to LA (315 miles for me to my mom's door) and only burn 3/4s of the tank. I've replaced the air filter, at least every other time with the oil, often everytime. I replaced the fuel filter at 20K and I'm at 33.3K now. Did plugs at 30K also with Bosch 1 point platinums. I tried replacing the PCV valve, but was affraid I was going to break it, and I don't think that that would cause such a huge drop in mileage.

The real cause of confusion now is that I recently had a smog check and it's running as clean and lean as a Honda.

Here's the results [15MPH/25MPH]:
15MPH / 25 MPH
CO2%: 15.0 / 15.1
O2%: 0.1 / 0.0
HC(PPM): 3 / 0 (Average 9/7; Max 52/36)
CO% 0.02 / 0.00 (Average 0.02/0.03; Max .49/.46)
NO(PPM) 0 / 0

So it's not running ANYWHERE near rich. So the question remains, why do I have such crappy fuel mileage. I also run my tires at 35 PSI cold, and had an alignment just before X-mas and it was too badly off, just pulled left (didn't want to drive to LA on a bad alignment). At first the guy at Autozone suggested I might be getting my gas stolen, so he weasled me for a 20 dollar locking gas cap, and still bad. I also had the smog check with the locking gas cap and it passed no problem, so it's not leaking out of the tank. I've even tried not going WOT as often as I usually do, and still only 250 miles per gallon. Maybe it's just something with the flex fuel engine and I don't know. Maybe it's just usual. Let me know what you guys think.

-mobiuslogic

 

[fvt]

Originally posted by mobiuslogic@Jan 16 2004, 01:27 AM
Alrighty guys, this has been a cronic problem for me. I always get about 250 miles per gas tank (16 gallons, not the bigger 18). The only time I ever got more was 300 miles ONCE! Literally once. Next time I got 275 and the third was back down to 250. This is only city driving. On the highway I can get to LA (315 miles for me to my mom's door) and only burn 3/4s of the tank. I've replaced the air filter, at least every other time with the oil, often everytime. I replaced the fuel filter at 20K and I'm at 33.3K now. Did plugs at 30K also with Bosch 1 point platinums. I tried replacing the PCV valve, but was affraid I was going to break it, and I don't think that that would cause such a huge drop in mileage.

The real cause of confusion now is that I recently had a smog check and it's running as clean and lean as a Honda.

Here's the results [15MPH/25MPH]:
15MPH / 25 MPH
CO2%: 15.0 / 15.1
O2%: 0.1 / 0.0
HC(PPM): 3 / 0 (Average 9/7; Max 52/36)
CO% 0.02 / 0.00 (Average 0.02/0.03; Max .49/.46)
NO(PPM) 0 / 0

So it's not running ANYWHERE near rich. So the question remains, why do I have such crappy fuel mileage. I also run my tires at 35 PSI cold, and had an alignment just before X-mas and it was too badly off, just pulled left (didn't want to drive to LA on a bad alignment). At first the guy at Autozone suggested I might be getting my gas stolen, so he weasled me for a 20 dollar locking gas cap, and still bad. I also had the smog check with the locking gas cap and it passed no problem, so it's not leaking out of the tank. I've even tried not going WOT as often as I usually do, and still only 250 miles per gallon. Maybe it's just something with the flex fuel engine and I don't know. Maybe it's just usual. Let me know what you guys think.

-mobiuslogic

how about your fuel lines? any leaks/corrosion , etc anywhere?

 

[theman21]

Really all depends on how you drive. If you are driving 70+ on the freeways your gasmileage will go down. Same way if you do jack rabbit starts around town it will do the same. My bull averages around 20-21mpg with light city and mostly highway driving. I carry around excess stuff, drive generally 70+ on the freeways with the AC on, and drive a little agressive around town. I have also the 16 gallon tank and I generally get at least 300 miles on a tank of gas. I have gotten further like 350 doing mostly highway driving. I would attribute your gas milleage to city driving especially in LA. The other thing you might want to do is run fuel injector cleaner once a month. I generally do and it keeps things clean.

from what you said you are averaging around 16-17mpg around town.
I pulled this info off the net.
Avg. mpg, city/hwy:
Standard 3.0-liter V6 20.9/26.6
24-valve 3.0-liter ohc V6 19.2/25.1

Well its a little less than the average of around 19.2. Might want to take a closer look at some things. Try the simple stuff first, lighten the load, clean the injectors, drive more conservatlivley. If not start looking at MAF, O2 sensors and other lovely things that can go wrong.

good luck.

 

[mobiuslogic]

How could I have a bad MAF or a bad O2 sensor and still get such phenomenal smog numbers? In fact the guy thought I was making it run lean it was running so well. Also, I don't carry anything in the car except for the spare tire, jack, and a 2 1/2 foot length of ultra high density polyethlene that I've never bothered to take out of the trunk. Plus it only weighs about 2 pounds. And I live in Santa Clara but I drove I-5 to LA, which is when I got good mileage. I also run fuel injector cleaner everytime I change the oil, at least. Usually about once a month actually. I want to keep my 24 pounders nice and happy.

As for "jack rabbit" starts, I usually don't top 2500 rpms off the light, but when I gun it and need to be somewhere to merge, it's WOT all the way. That's thanks to the bad drivers in the South San Francisco Bay Area. They don't watch anywhere around them, so if you see a gap, you need to get in there cause they'll never look for you coming.

So I'm still wondering. I never have changed the PCV valve, I guess that would be a good place to start.

-mobiuslogic

 

[Twilight]

If it's not running rich at all, I don't get it. How do the smog checks in California work? Is it at idle or with the car moving?

Since you don't have snow there it's kinda weird. The only other thing I would consider is the type of gas being used. My car will get better mileage on gas from different stations.

 

[mobiuslogic]

California has literally THE strictest emissions laws of all the other states. In fact if you buy a car in CA it'll say 50 state legal emissions. Sometimes if you buy a car OUTSIDE of CA it'll only be 49 states legal, that 1 being CA, but that depends on the maker. But in CA we've switched over to "Smog 2" which is a smog test under load on a dynamometer (don't know about other states). It used to be with the engine in neutral at idle and then 2500rpms, but they switched it to with the engine under load so that it'll be harder to pass and gross poluters will fail more often. So yeah, I don't know what the deal is. As for the type of gas, we've got Arco, Chevron, Shell, Valero/Beacon, and 76. The 76 station by my house competes with Valero/Beacon and the Arco down the street on regular gas, so I usually go with the 76, however it really doesn't matter as I get the same with any gas. I think I'll go buy a PCV valve and put it in right now.

-mobiuslogic

 

[sixfofalcon]

Your mileage problem stems from your right foot.

As far as 70mph+ on the freeway getting you bad gas mileage... well, my results differ. I got a whopping 29.9mpg from Boston to Philly, and I only dipped below 80mph twice. Once near Hartford, and then about 45 minutes of traffic jammage in NYC. I would guess it depends alot on which Gen you have, though... the Gen 1/2 has poor aerodynamics.

 

[mobiuslogic]

I don't know about my lead foot problem. I typically keep it right near the speed limit. As for the freeway I get great mileage. Like I said when I drove to LA for X-mas I got almost 28 miles to the gallon and I had the cruise on 75 the whole way down.

I replaced the PCV valve and it turns out that the 90* molded hose was cracked, so I put a new hose in there as well as the PCV but I won't know about gas mileage for a bit. The PCV was really clean though, even on the inside, so I don't really think I needed it, but oh well. At least I caught the cracked hose.

 

[Guest]

ok, I think this is a good a place as any to interject.

I just edited several posts in this thread.
The topic is about fuel mileage, let's stay with that or the thread is done. Just limit the description to them being crappy drivers (regardless of race, gender, hair color, shoe size, etc) and there can be no misunderstandings.

 

[pc_marine]

My 2000 FFV Taurus gets about 250 miles till the gas light turns on with 100% city driving and in sub-freezing weather.

 

[Twilight]

Another thing you might want to check would be the IAT. I think mine is busted, or just not secured properly, but the symptoms are similar. I am however running extremely rich in cold weather and more normal in regular weather. Perhaps in the dyno facility your car didn't have enough time to heat up.

Right now I am getting ~150 miles until the gas light turns on. I used to get around 300, and when it warms up again I'll get 300 again. I'd attribute some to this, and some to tires spinning due to snow all over the place (but I guess that's not a very big problem in CA).

 

[fanofelliottmjb]

My wife and I just went to Florida from Illinois during Christmas. Filled up 4 times there and back. When I kept the speed constant we would break 30 MPG when we got to the mountains/foot hills we got 27 MPG. When we drove in town in Florida we got 24 MPG. Lots of stop and go hardly any drag racing. These are the same results every time we have made the trip in this car. 3 times in the four years.

It seems if you keep it steady the milage gets better. I replaced the PCV valve just before we left at 93,000 miles and didn't notice any difference.

Monte

 

[mobiuslogic]

I don't know about the IAT. After I found the cracked hose, I checked out all the other lines, and hoses and the MAF connectors, the TB, and the upper intake. Nothing seemed loose or out or the ordinary. Maybe my bull just plain gets crappy mileage.

However my results are consistent with PC Marine. I get to about 225-250 then the light goes on and I'll fill up between 250-275. Considering that he has an FFV also, I think it may just be something with the FFV system. I guess that that extra little bit of power comes at a big price.

-mobiuslogic

EDIT: As for the dyno smog check, the car was all warmed up because I had been driving that morning. Plus catalytics work better when they are hot, so I made sure the whole car was all warmed up. As for the wheel spin, it's typically never a problem unless it's self-induced.

 

[ragtop88]

WHen I lived in Atlanta, I use to get crappy gas mileage part of the year since during high smog potential times they switched to reformulated gasoline, and I had heard others saying the same thing. Does California use re-formulated gas? The same gas stations carried the different stuff just depending on time of year. Also I'd tend to think the city driving is whats doing it, since you do get fine mileage on the highway under those conditions. If something was really wrong, it would show up all the time.