My car has burnt almost a half a tank of gas in 60 miles (2002 Nissan Maxima)

I have a 2002 Nissan Maxima SE (Automatic) it just started to run rough and has been drinking gas at an alarming rate. Almost 1/2 tank in about 60 miles. The car doesn’t seem to be running slow or smelling of gas. I was told it was fuel injection issues and have added some cleaner but I am shocked with how bad it go so quickly. I had two motor mounts replaced in the car recently (the front one a day before this started). Would they have knocked something out of wack?


I would take the car back to the shop that replaced the motor mounts

Explain the situation and politely ask them to recheck their work

Check engine light on?

Could have a problem with the engine coolant temperature sensor . . .

Some sensor is way off and not operating and causing a way too rich fuel mixture. You need to have a computer scan done ASAP to determine the issue before you wreck the converters.

hmm … if the tank holds 12 gallons, that would 6 gallons of gas used in 60 miles. 10 miles per gallon. Was this a lot of stop and go driving, a lot of idling? If not, I’ll bet some sensor wasn’t re-connected, or the connections were swapped, as part of the engine mount replacement. Usually that would turn on the CEL though. If this happened right after the prior repair, doubt fuel injectors are the problem. As mentioned above, the coolant temp sensor is a likely culprit. But it could be the MAF/MAP or the O2 sensors too, among others. If something isn’t found by a visual inspection – good idea as mentioned above to ask the prior repair shop to take a look – then you’ll probably need to find a shop who specializes in this make/model and has the appropriate scan tool for the engine. It might be a good idea to check the valve clearances, if that is part of the routine maintenance suggested by Nissan and it is over due. There’s a good chance in any event it will be relatively easy to fix once the cause is determined.

Thanks for the responses, I decided to stop driving the car - for all of the obvious reasons. Right before I stopped I burnt 1/8 of a tank driving 6 miles…

I am surprised but it isn’t throwing up any “check engine” light even though I would think it would.

One of the factors is that I replaced one of the engine mounts that had a sensor with one that doesn’t have a sensor, though no one can seem to tell me what the sensor does. The non-sensor version was suggested as a replacement. My mechanic didn’t know either so he installed it.

I would agree with your statement GeorgeSanJose - I should have started with a mechanic specialized in my car. I liked the guy I went to but in the end it might have been better to go with someone who knows the “idiosyncrasies” of Nissan.

Thanks to all.


Not all fault codes require the check engine light to turn on

Even if you go to a non-Nissan mechanic, if that guy uses genuine Nissan parts, chances are you’ll be okay . . . as far as straight-up repairs and maintenance goes. As for diagnosis, it might be a gamble, depending on the guy’s competence level and access to service information.

That “sensor” changes motor mount stiffness to reduce idle vibration:

What is not clear to me is…
Is the OP basing this amount of gas consumption on the gas gauge, or is he basing this on an actual calculation of his gas mileage?

If the OP is basing all of this on the reading of his gauge, that is not a good way to approach this situation, and a coincidental problem with the float/sensor in the gas tank or with the gauge itself could be to blame for his belief that the car is consuming gas at an astronomical rate.

I agree with db4690, check the coolant temp sensor. Some older cars are not smart enough to time the engine warmup and set codes. They stay open loop as long as sensor inputs tell them to and so don’t set codes. Not sure if true here but a scanner should reveal what the computer sees and is doing to cause excessive gas injection. Other “leaks” are possible but rule out intentional reasons first since it’s easy…

Good call across the board…

It is true I am noticing the gas gauge and not checking the MPG any other way.

I appreciate the link for the sensor, as it seems that no one I talked to seemed to know what it did. It does concern me a bit as the car is running so rough after the replacement so I am not sure what “broke the camel’s back”.

At the end I will have to bring it back to the mechanic and see what he says, though this thread has helped me ask questions I don’t think I would have normally.

“It is true I am noticing the gas gauge and not checking the MPG any other way.”

First, calculate your gas mileage, by dividing miles traveled by the number of gallons that it takes to refill the tank. Preferably, this should be done over the course of 2 or 3 fill-ups to get an accurate real-world figure, but, if you come up with a really dismal number on the first try, then you should probably go to the mechanic right away, before you do more potential damage to the catalytic converter.

On the other hand, if the actual rate of gas consumption is normal or near-normal, at least you will have a better idea of what you want the mechanic to fix.

Anyway…the moral of the story is to never assume that your gas consumption has changed, simply because of what the gas gauge is indicating.