Under 8 MPG (4 Viewers)

[effjay80]

Just got back 1,600 mile road trip 33" KO2s inflated 40psi, mostly highway 65 to 70mph, pretty tame weather no wind either way. Straight stock tuned intact 1FZFE. Ran 87 octane as always.

13.8 mpg. No surprises either way.

 

[manofthewoods]

Just got back 1,600 mile road trip 33" KO2s inflated 40psi, mostly highway 65 to 70mph, pretty tame weather no wind either way. Straight stock tuned intact 1FZFE. Ran 87 octane as always.

13.8 mpg. No surprises either way.

Interesting, same tires, pressure, and speeds (generally). 4,000 miles hunting trip, lots of driving each day. On good gravel roads mileage was 15ish.
Massive head wind on I80 across Wyoming (common) 14mpg.
Next day calm across Nevada was low 17mpg. Last segment was Fernley NV up and down the Sierras to east Sacramento, exactly 18mpg.
Similar trip a month earlier I had 2 tanks go mid 18mpg. Seems like my best mileage is when temperatures are between 40 and 55 degrees.
YMMV

 

[effjay80]

I would bet I could hit 16mpg purring along at ~55mph as I'm sure there's a mpg efficiency peak somewhere below 65mph. I'd just never get anywhere.

Just remains such a joy to trundle aimlessly along in my 80. No love lost since 1994.

 

[jjdeneen918]

Current fuel up was about 7.5. That is with the PO130 & PO133 (both O2 sensors) activated.

I’m thinking bad cats, or an exhaust leak. I can hear the slightest ticking noise if I really listen for it.

Can’t get it back to the shop as my Subaru just went back to the shop with a fuel leak at the tank.

Hopefully get it back soon & my LX450 goes back to the shop.

 

[thabruiser]

I may have missed it, (I did read through the whole thread!) but other than being at sea level, is this mostly highway driving? Is your engine always getting up to operating temps every time you drive? (i.e. going into Closed Loop). And, had you been keeping track of the MPG's before the turbo? I have a similar setup, but with 33" tires, non turbo. I drive short trips ( Mostly 3 mile trips back and forth to work) and am getting roughly 9.5 MPG. Last tank was 155 miles, and 16.5 gallons IIRC. Many "fuel consumption" concerns are hard to pin down to any one thing (unless the vehicle tells you via CEL that something is wrong) due to the one factor that is hard to duplicate with another person: driving habit. This is not to say you've done something wrong. Just that it may be something you haven't thought of, that you are doing without even realizing it.

 

[jht3]

i suspect your odometer gears are busted and not spinning as often as you think. typically its an issue with the trip odometer lever. as long as i dont touch my trip lever, its ok, but on my list of things to fix. already have a spare speedo/odo unit to borrow for parts.

285/75R16's, non turbo, ARB front, Frontrunner rack, and most of my driving 4mi up and back through 4-5 traffic lights I get about the same mileage according to fuel used and mileage. UltraGauge will report better numbers as I've GPS calibrated it. I don't have the numbers in front of me, but from memory the uncorrected MPG is ~9 and corrected ~11-12. On a road trip i can see ~15 doing 65-70. Pre-cat O2 replaced in the last few years too. Also on my to do list is clean the injectors and replaced all vacuum related parts under the manifold....no CEL's but i know it needs attention. Will also check the IAC.

 

[elripster]

So did you unplug the O2's and drive? Just want to make sure we understand the test. If you did we then need to look at the remaining sensors and see why the base injection duration is too long allowing for too much fuel (assuming you are sure you don't have a leak somewhere...).

Let's get some data. Can you order this from Amazon? Amazon product ASIN B073XKQQQW
You might even get it the same day. I use the Torque app (not Torque lite) and it will let you see realtime data. Get everything that has anything to do with mixture, O2 voltages pre and post cats, air flow, all temp readings. Pull fault codes, note them, then clear them, then go for a drive. Also, after the drive, use an IR temp sensor to see how hot the cats are.

If nothing definitive comes from this, pull the spark plugs and post pictures of each. You might even do a compression check during this just to check that off. As noted, if you are concerned the cats are plugged, and running this rich they very well could be, just go to an exhaust shop and have them blow out the cats and ensure they are clean. Cats are stupid expensive these days so I am sure you'll want to see if they can be reused vs. having to be replaced.

I put the attached spreadsheet together for troubleshooting my 94 which is OBD1 so some of it won't apply to your 97 but a lot of it will.

Frank

 

[elripster]

My trip odo doesn't work either. Key question then, was the drive between points where the distance aligns with the odo?

Frank

 

[jjdeneen918]

I have not run it with O2 sensors removed, as I don’t have a bung for the hole. Are you stating to do that, or just unplug them?

I have a ScanGuageII & an JRP display. So I do get AFR, oil & water temp, oil pressure, open/closed loop, ect.

 

[elripster]

I meant unplug the O2's not remove them entirely. It forces the engine to run open loop and can help to point to different sensors as being an issue or not.

What does the scan gauge report for those values?

Frank

 

[White Stripe]

Do you have a check engine light on?

 

[jjdeneen918]

Yes, engine light is on.

Codes PO130 & PO133 (both O2 sensors.

No values, just the codes.

 

[elripster]

Can you see what the O2 voltages are, are they fluctuating? Also, can you see the Vf voltages? We really need a lot more information to solve this. There are a lot of potential causes.

Keep in mind a rich engine leads to cool exhaust which means cool O2 sensors which will fail to fluctuate and appear to be bad. The rich condition could be O2 sensors or something else. You could try some new sensors?

Frank

 

[jjdeneen918]

02 sensors are about 2 months old. So I’m just going to go back to my shop soon to have them diagnose.
Just waiting on my Subi to get back from a fuel leak.

 

[elripster]

Sounds like a plan, let us know what you find.

Frank

 

[sogncab]

I won't bitch about economy anymore.

For Thanksgiving I drove 3100 miles round trip to south Florida. 35' BFG AT's. Stock gears. Pulled basically 15mpg the whole time with the cruise set at 71mph.

Speedometer is corrected with the Lutz Auto widget. If I drive 300 miles, the odometer reads 299 miles. I think that means I'm within .3%

I replaced my fusible link recently. I was getting three codes repeatedly that I couldn't figure out the solution to. I've put about 400 miles on since changing it out. No codes, runs better, shifts better. Dumbest thing ever

 

[BILT4ME]

I won't bitch about economy anymore.

For Thanksgiving I drove 3100 miles round trip to south Florida. 35' BFG AT's. Stock gears. Pulled basically 15mpg the whole time with the cruise set at 71mph.

Speedometer is corrected with the Lutz Auto widget. If I drive 300 miles, the odometer reads 299 miles. I think that means I'm within .3%

I replaced my fusible link recently. I was getting three codes repeatedly that I couldn't figure out the solution to. I've put about 400 miles on since changing it out. No codes, runs better, shifts better. Dumbest thing ever

That's because having it disconnected cleared all settings. See if they come back after about 30 start / stop cycles.

I have found my sweet spot is about 60-65 MPH, but I'm too impatient to drive that slow.

 

[sogncab]

That's because having it disconnected cleared all settings. See if they come back after about 30 start / stop cycles.

It's gotta be simpler than that. I had the battery unhooked overnight prior to the trip. I had codes in no time. Like the morning of the trip the coolant temp sensor popped up.

But, I am retarded, and could be way, way wrong.

 

[BILT4ME]

It's gotta be simpler than that. I had the battery unhooked overnight prior to the trip. I had codes in no time. Like the morning of the trip the coolant temp sensor popped up.

But, I am retarded, and could be way, way wrong.

OK, you just stated you had no codes.

What codes you are getting can affect it. For example, if the temp sensor fails on the "high" side, then it will tell the ECU that it's in closed loop early and it will lean out the fuel, getting better mileage, but it may run like crap when cold.

 

[sogncab]

OK, you just stated you had no codes.

What codes you are getting can affect it. For example, if the temp sensor fails on the "high" side, then it will tell the ECU that it's in closed loop early and it will lean out the fuel, getting better mileage, but it may run like crap when cold.

I have no codes after swapping the fusible link.