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2001 V6 Camry questions

Hello all just seeing if I can gather any more info into what may be wrong with my ride. Car has 160k on it and has been solid for me. Recently after a cylinder misfire I had the faulty ignition wires changed as well as a routine oil change. Since then my mpg seemed to dip significantly so I was looking into what that may be. After going through two full tanks and clocking out at 25 mpg both times (which I’m very happy with for an old v6) I’m wondering why my gas level is fluctuating as much as it is. The level won’t be less after getting in after sitting overnight, but any drive whether it’s an hour commute or 5 minute round trip to the store seems to make my gauge drop. Anyone I’ve gone to hasn’t really known what’s up or thinks I’m full of bs because I’m still getting 25 mpg. No change in driving pattern and have not had a check engine light since the misfire. Only other noticable thing it has been doing is between 1-2 gear 30-40 mph there has been some engine vibration that simulates going over several small bumps while driving

The gas gauge may be malfunctioning. What was your gas mileage before? The drop might be due to the winter gas formulation, which does provide slightly lower fuel economy.

Does the Camry’s fuel level start out at one position, then drop as it is driven ? (at least that’s what it sounds like)

My Prizm does that (made with Toyota parts). I suspect it has to do with the gauge returning to a neutral position when the car isn’t on - then slowly going to the correct reading when the car runs.

I hadn’t clocked it in some time but it had to be around the same because I drive 80 percent highway I’d say. There’s no way I could maintain that mpg with a leak somewhere?

Capri yes that does seem to be the case but after a normal 40 minute round trip drive that I do regular I was starting to see it use around a quarter tank, when it usually would move maybe a half inch

If you have a leak, you should smell gasoline.

“Only other noticable thing it has been doing is between 1-2 gear 30-40 mph there has been some engine vibration that simulates going over several small bumps while driving”

what do you mean? do you watch your tach? is rpm at 2k or so at 55mph? trans issue may affect mileage

There are a couple of things that could cause a sudden drop in fuel mileage.

One is a thermostat that’s stuck partially or fully open.

If the thermostat is stuck open, the engine doesn’t get up operating temperature. This will causes the engine to use more fuel.

Another is a faulty coolant temperature sensor the computer.

If this sensor is telling the computer that the coolant temperature never gets to operating temperature when it actually does, the computer will think the engine is still cold, and this will cause the engine to use more fuel.

Tester

On the other hand, winter blend fuel will deliver worse mileage. The other thing is every time you start the car will suck up a lot of gas. I can go through a quarter tank just 50 miles around town starting and stopping for short trips taking a while to fully warm up.

I’m confused- is your problem poor mileage or inconsistent gauge readings?

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It sounds from OP’s posts the mpg is as expected, car runs well, just the fuel gauge is acting weird. That’s likely either a faulty fuel gauge sender unit, faulty fuel gauge, or faulty gauge voltage regulator. You car has 160k miles? Probably the best bet is to just ignore it until there’s another reason later on that requires to remove the gas tank or the dashboard. If OP wants to do something as a diy’er, OP could verify the voltage at the battery is behaving ; i.e. 12.5 volts before starting the car after it sits overnight, 14-15 volts after starting the engine, slowly dropping to 13-13.5 volts as the engine warms up and the battery charges.

The shuddering at 30-40 mph may be a problem with the lockup function on the torque converter assuming OP’s car is an automatic.