'96 5sfe - sudden increase from 28mpg to 39mpg?!?!

[79kz400]

I was getting 27 - 28 mpg freeway (I put 10K on in the last 6 months)
Drove 800 miles from OH to MO 2x in Dec/Jan and I've got the economy down pat.

Yesterday I fill up (28.01 mpg @ fillup like usual) and drive 45 miles freeway and today about 140 miles. 53 miles of highway driving - NO Cruise control, windows up and no AC on. Some drafting on the e-way for about 30 miles behind an SUV. Freeway speeds @ 70-75mph with bursts over 80mph. Heavy cross winds today.

Total Miles - 238
Total gas to fill - 5.958 gal
Total Fuel Economy - 39.61 mpg

1996 Camry LE 5sfe 2.2L 4cyl. auto 178,000 miles, 110-120lbs of speaker stuff in trunk + 30 lbs of tools.

Everything appears normal - I work on cars a lot and would notice anything out of the ordinary. I recently drained and filled the tranny, and changed the fuel filter. This was about 350-400 miles ago. I made and installed a grounding wire kit that helped a lot with shifts and +1 or 2 mpg but that was 5000 miles ago.

It did this once before when I drove back from MO - 34.5 mpg then.

Should I worry? I've never had a car do this before.
I can't get photobucket.com to let me sign in but I took photos of receipts - I'm concerned - I'll pull plugs and check for lean burn later tonight.

[79kz400]

Plugs look just fine - Clean and lightly colored - Due for replacement but OK otherwise. Light ash deposits maby? Photobucket still down.

[popeye08]

How do you calcuate the 5.9 gallon to fill? If it just because the pump is stopped, it doesn't mean it is filled. No offense, I think it is impossible to get a 39 mpg for a Camry 96 5sfe unless you were always down a hill.

Originally Posted by 79kz400

I was getting 27 - 28 mpg freeway (I put 10K on in the last 6 months)
Drove 800 miles from OH to MO 2x in Dec/Jan and I've got the economy down pat.

Yesterday I fill up (28.01 mpg @ fillup like usual) and drive 45 miles freeway and today about 140 miles. 53 miles of highway driving - NO Cruise control, windows up and no AC on. Some drafting on the e-way for about 30 miles behind an SUV. Freeway speeds @ 70-75mph with bursts over 80mph. Heavy cross winds today.

Total Miles - 238
Total gas to fill - 5.958 gal
Total Fuel Economy - 39.61 mpg

1996 Camry LE 5sfe 2.2L 4cyl. auto 178,000 miles, 110-120lbs of speaker stuff in trunk + 30 lbs of tools.

Everything appears normal - I work on cars a lot and would notice anything out of the ordinary. I recently drained and filled the tranny, and changed the fuel filter. This was about 350-400 miles ago. I made and installed a grounding wire kit that helped a lot with shifts and +1 or 2 mpg but that was 5000 miles ago.

It did this once before when I drove back from MO - 34.5 mpg then.

Should I worry? I've never had a car do this before.
I can't get photobucket.com to let me sign in but I took photos of receipts - I'm concerned - I'll pull plugs and check for lean burn later tonight.

[79kz400]

I agree with you. I don't believe that its possible either, and it happens randomly so I wonder why it happens.

Since fuel economy is only ever an estimate. Here's how I get mine.

#1 - I let the pump stop. Then I hold it open untill it stops. Then I squirt in enough to round out the dollar ammount up to $.25

#2 - I monitor my gas gauge. Yes, the float will change with angle, but when it says i've got 3/4 tank in level transit, and I put in just under 6 gallons, I guess its right.

I've been through this. Numerous experiments over many years and half a dozen cars. Things like angle of parking lot (you'd be amazed at how much a 2 degree grade can change things) and how much gas one should really put in. Yes, OBD II is sensative to evap BS but i've never had a problem.

Yes, fuel expands as it gets warm, it was warmer today, and that could contribute to slightly larger volume in tank. I once ran fuel through a copper line around the lower radiator hose on a 1991 Sentra for 3 months. Warm fuel = better atomization + lower density. Jacked up the timing to 12 degrees and went 41 mpg routinely with exhaust and intake mods + fabbed up heated O2 sensor. Nissan Sentras are suposto be about that good. Camrys are not...

No, I didn't have my GPS with me. I do have one and the speedo is about 2 mph fast at all speeds so I really go 57.5-58 miles when it says 60. No, I didn't bother to factor that into the calculation. Lets do that. 240 miles (rounded) / 60 = 4 so subtract 4 (from rounding) and another 8 (lets guess 10) total 14 = 240-14=226 total actual miles
226/5.958 = 37.93 mpg actual fuel economy - Waaaayy more than it should get.

I monitored a massive jump in fuel ecomomy and I wondered if anyone else had ever noticed this on theirs. Its the second time I've seen this. Last time was about 50 degrees, high humidity, with constant drafting in high speed traffic (75-85)

Timing light says 5 degrees of advance....

[xfeejayx]

I've gotten 35MPG once or twice. was probably averaging~72MPH. I figured it was just a tail wind.

[79kz400]

Thanks, i believe that. I've noticed that summer blend gas + high heat (over 90) I get better fuel economy than usual but never in normal driving conditions.

Fuel economy is back to normal. Must have been a fluke.

[rprough]

I have a 2004 Camry and on a recent trip from Pa. to SC, we managed to get 40 mpg! Not bad with 3 adults and some luggage and the ac on low. We filled up in Pa. and did not have to fill back up till we got to SC again. Not bad.

[Mike Gerber]

This type of mileage anomaly can be caused by a strong tail wind and/or a downhill slope of the road for an extended drive. It can also be caused by an air pocket in the gas tank when refueling or a gas pump that is overly sensitive. Also remember, you only put in about 6 gallons. That is less than 1/3 the capacity of your 18-1/2 gallon tank. Any abnormality in refueling will be greatly exagerated when only refilling that amount of fuel. It will be interesting to see your fuel mileage on your next fillup. I wonder if it will show mileage much less than your normal average; highway or city, whatever you drive before the next fillup.

I also have a 94 5SFE and have never had highway mileage anywhere near this. I usually get around 29-30 MPG. Once, when I was fighting a very strong cross wind, I only got 25 MPG. That too I considered an anomaly due to the strong cross wind.

Let us know what your next few fillups show.

Mike

[CF#5]

In 1996, I drove with my mother from Rochester down to New York in her 1995 Camry with the same engine. Kept cruise control on the entire trip at 55mph, never went over 60-65mph, and gave it some gas as we were approaching hills to increase the speed so the transmission wouldn't downshift on its way up the hill. Ended up using about 7.8 gallons for about 300 miles, give or take, for about 38.5mpg. But I was really going out of my way to do that.

[erapp]

My 1996 DX 5SFE w/ 5-speed started doing the same thing around 200k miles; the gas mileage jumped from ~29-30 mpg to ~40 mpg even though I didn't change my driving style at all. Then I started paying attention to the highway mileage markers and realized that my odometer was way off... the odometer was recording 1.6 miles to every REAL mile between the markers making it seem like I was getting extra ordinarily good gas mileage when in fact the recorded miles were actually 1/3 shorter than a real mile.

[somick]

Originally Posted by erapp

My 1996 LX 5SFE w/ 5-speed started doing the same thing around 200k miles; the gas mileage jumped from ~29-30 mpg to ~40 mpg even though I didn't change my driving style at all. Then I started paying attention to the highway mileage markers and realized that my odometer was way off... the odometer was recording 1.6 miles to every REAL mile between the markers making it seem like I was getting extra ordinarily good gas mileage when in fact the recorded miles were actually 1/3 shorter than a real mile.

1 mile = 1,609 meters. Exactly what you are getting on your odometer.

It is probably set to kilometers.


Sam

[erapp]

Originally Posted by somick

1 mile = 1,609 meters. Exactly what you are getting on your odometer.

It is probably set to kilometers.


Sam

That's been brought up before but I have yet to read/hear how it's possible to switch between miles and kilometers on the same car. I think it's coincedence because the speedometer still reads accurate (doesn't indicate 100 mph while traveling w/ traffic doing 65 mph).

[somick]

Originally Posted by erapp

That's been brought up before but I have yet to read/hear how it's possible to switch between miles and kilometers on the same car. I think it's coincedence because the speedometer still reads accurate (doesn't indicate 100 mph while traveling w/ traffic doing 65 mph).

My dash (2004 LE) has a button for switching.

Do you happen to have owner's manual? It may be mentioned there.

Sam

[erapp]

Just a quick update... I'm still driving the same car, now w/ 252k 'hybrid' miles/kms.

To answer the previous post; my '96 doesn't have that switch. I'm guessing your's is electronically displayed & mine has physical tumblers that roll over.

[wildwilly49]

I HAD THIS HAPPEN TO ME ONCE. I HAVE A 99 CAMRY AND I STARTED GETTING 45 AND 50 MPG. I FINALLY DISCOVERED THAT ONE OF MY NEIGHBORS WAS PUTTING GAS IN MY TANK AT NIGHT. THATS WHAT I GET FOR LEAVING IT UNLOCKED.