No way Jose.
If there’s the slightest problem with the up-stream air/fuel sensor, the Check Engine light would be glaring.
OBDI?
Maybe.
OBDII?
Check Engine light.
Tester
The thermo has not been changed. I might do that but it will have to wait until the temp improves a bit.
LOL. Yes, my mileage improves by 50% using summer blend!
I have replaced the downstream ox sensor and it clearly showed up with the CEL and a scan. Nothing on the upstream sensor.
So, same exact tires as before? Same brand, same model, same tire in every way? I see Mustang man asking, but no answer. Tire model changes can affect MPG this significantly based on my experience.
Same tires have been on the car for several years.
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I agree with John
I’ve personally seen fuel economy reduced by 2mpg, due to a different brand of tires
Why don’t you tell us the brand of tire, so we can all avoid it?
Naming the brand really might not mean anything. It could be less efficient than ones a person had or better than the ones they had. Size of tire, thread pattern and even the vehicle itself could matter.
You will have to excuse me. I was being sarcastic. Personally, I don’t believe any brand of tire will reduce mileage by 2 mpg unless it’s a pickup truck switching to heavy lug off road tires.
2 mpg with this car is 8%. Very easily tires. Now he actually says 3 mpg by my math which would be 11%. Still possible, but less likely. Wander around Tire Rack’s site sometime and compare the ratings on various tires of the same size for fuel mileage. Its a fairly wide span. But the OP did post he had the same tires answering my post.
Triedaq, I did some quick calculations and figured out that by replacing your 6.95x14 tires with 7.75x14 tires you increased the rolling radius of your tires by +/- 6%. What this means is your 70 mph indicated speed was actually closer to 75 mph. Given that hardly any '60s and '70s cars were paragons of aerodynamic efficiency, that small a difference in real speed could have quite a significant effect on your mileage. However, your engine should have been turning about the same rpm (you didn’t mention whether or not you had a tachometer). But again, even at the same rpm your engine would have been working harder to push the car through the air, so that might have been enough to cause your oil usage to increase to some extent.
@Dakotaboy. I never took the time to do the calculation. We were finishing our coursework in graduate school and the 1961 Corvair I purchased 4 years earlier had a transmission that was going out. We had accepted jobs and needed a car to get us out of town. I bought the 1968 Javelin at s good price but it needed tires. The front tires were bald and the rear tires were studded snow tires. I bought the car in May and the studded tires weren’t legal to use after March. I saw two 7.75 X 14 tires advertised on our bulletin board in our married student housing bulletin board. The tires had plenty of tread and the price was right. I took the tires to the Amoco station where I did business and bought two new Atlas 7.75 X 14 tires for the rear wheels. Money was tight for us but I got s good car and had safe tires. I got the Javelin at wholesale book because the odometer read 33,000 miles but the dealer left the state inspection record in the glove compartment and the car had been inspected 3 months earlier with 55,000 miles. Also, the engine in the Javelin was a 232 6 cylinder. The Javelin was the American Motors answer to the Ford Mustang. It would have been worth a lot more money if it had had a V-8 engine. I actually preferred the looks of the Javelin to the Mustang or Camaro.
It might be that your fuel supplier is using a different winter blend of gasoline.
Maybe the extra-low temperatures this year has to do with it.
Just FYI. I just checked my mileage again after I added Techron fuel injector cleaner and MPG has gone from under 24 to under 26 now.
Where I live this winter, unusually frigid for the past two months +, has been absolutely brutal on my gas mileage. The engine takes a lot longer to warm up, the tranny fluid is I’m sure thicker, bearing lubricants are no doubt thicker, and tires have to roll over roads that are covered with snow, salt, and sand, not their usual relatively low-resistance surface. If you, OP, live north of the 40th parallel, that alone may be the problem. You won’t really know until the weather warms up and the roads get cleaned by spring rains and in many areas street sweepers. A good look at the condition of the streets gives new meaning to the term “spring is busting out all over”.
Bottom line: it’s been an unusually frigid winter. That can easily be the reason for the drop in gas mileage.
It has been cold here in the Eastern US. Not so much out west. Utah has been extremely warm. i looked at the temperature a couple weeks ago, and it was 52. That’s 50 degrees higher than it was at the same time two years ago when I was there for a few weeks.
I’m in the Northeast, and it was 60° this week.
Me too, well, almost. I’m in MD. But it has be quite cold until recently. Northeast Utah is usually very cold by my standards, but maybe not by New England standards.
Where I am, NH, December and January were mostly well below freezing, often below zero. That kills everybody’s mileage. Mine included.