My car suddenly went from getting ~24MPG to 14MPG almost overnight. I've been through 3 tanks of gas now from 3 different gas stations and it's still 14MPG. As verified by how many gallons I actually put in, not just what the navi trip computer says. I haven't changed anything (how I drive it, where I drive it, etc).

I took it to the dealer for them to look at it but they won't help me much until I can provide them with 3 receipts for full tanks of gas... at the rate I'm driving now it will take probably 3 months to do that.

There are no codes coming up, no check engine light, nothing. Tire pressure is fine. My worry is that after 3 months and I give them the receipts, there will still be nothing to go by.

So, I plead to use oh Acura gods, do you have any suggestions?

 

14MPG is horrible. This is a 2.4L i4 cylinder.

If your repeated tests were consistent, ask the service manager to hop in the car with you (when you're tank is full) for "14-20 miles". Then fill up to see how many gallons go in. If he still refuses service, I guess your best bet is to drive around to get those damn receits.

 

I spoke with him and he agreed to drive the car through a quarter of a tank and see how it goes. He said he can probably get this done by Friday....... ugh. Don't want to be without my car for that long.

I'm still worried though that after that, all we have is the dealer believing me when I say it gets 14MPG. Still no codes, check engine lights, etc... what *mechanically* could be causing this?

 

maybe someones syphoning gas from your tank

 

O2 sensors or map sensors would be my buest guess.


Sort of unrelated but my mileage has gone down a bit since I got my summer tires. I think the tech that did my alignment dialed in too much negative camber and toe.

 

I would agree except a bad O2 sensor would light up the CEL and throw a code. This is puzzling.


And, WTF do they need receipts for? Its not like your lic. no. is on the receipts. You could get receipts anywhere.

 

An 02 sensor could be responding within the acceptable range but not relaying the correct information which could cause the mixutre to go seriously out of whack.

It may be worth having some else drive yoru car while you follow and get on the throttle hard to see if you blow out a bunch of black smoke

 

What is the estimated time per tank displayed on Navi Trip Computer? Try keeping track of the etimated time per tank.

 

cleaning/replacing the fuel injectors might also help the issue.

 

Do you also notice a large hesitation and lack of power? I had a problem like this in my old car. I had a broken temperature sensor, overheated but didn't know it and damaged engine internals. I was getting about 9mpg, serious engine hesitation and lack of power. Soon enough, black smoke out the exhaust. If you notice engine problems, take it in ASAP and have them drive it with you in the car.

 

with this kind of milage, I guess you may see black smoke coming out from the tail pipe.

 

I've heard of this happening in my neighborhood recently.

Do you park outside at night or in a well-hidden area during the day?

 

No, there's no way they could get to my gas tank

 

You check your tire pressure?

 

First U Have To Ck Your Air Filter, Tire Pressure At Hot Is 35 Psi, Did U Leave Your Engine On While Car Is Idling And Enjoy A/c?.

 

I Get About 23-26 Mpg. Base On My Normal Driving, Not Heavy Take Off On My Foot.
No Hard Corning, Etc.

 

5AT? Torque converter not locking?

 

i used to have bad mileage on my 4banger accord and it drove me nuts how i was getting 18mpg avg when i should be getting in the 20's... the rest of the cars in my family's garage have V6 engines and they got over 20mpg.

i tried to have the dealer check on it but all he gave me was the same "depends on different factors" BS regarding air temp, pressure, the way i drive, type of gas...etc.

switched to the TSX...been averaging 23-26 mpg...pretty good for 50% city driving

 

Okay, here are some ideas:

1) Take your car to an inspection station and have an emissions test done. If it does not pass, proceed directly to the Acura dealership with a COPY of the test report.

2) Jack up your car and ensure that all wheels rotate without much drag. A brake that is dragging (or emergency brakes out of adjustment) can cause a sharp drop in mileage and a related rise in wheel temperature.

3) Purchase a digital infrared thermometer and check the wheel temperatures after driving > 10 miles. If any one of them is elevated, then suspect either brakes or a wheel bearing.

4) Pull, and examine, the spark plugs after letting the engine run for 1 minute from a cold start. They should be dry and clean appearing. If they are wet, or black, or covered with carbon, then you have a O2 sensor, ignition, or computer (mixture control) problem. The engine is running much too rich. A disconnected vacuum line can cause rich mixtures on some cars.

5) Take the engine out to a fast road. like an Interstate, and stomp on it about a dozen times. WTO is what you want -- not necessarily speed. For example, if the speed limit is 65 MPH, find a safe area, drop to around 25 MPH, switch to Sport Shift, go to second gear, and then push the throttle to the floor board and shift at 7,000 RPM's. How does it pull? Weak, strong, or does it want to buck and backfire. If weak, it is likely a mixture problem (as in step 4 above). If it wants to buck and backfire, you likely have a timing chain that has jump timing. Do this several times if it does not buck and backfire. Otherwise, proceed directly to Acura.

6) Ask the dealership to check exhaust mixture (if they have the instrument), check ignition coils for strong spark, and check timing with a timing light.

7) I don't think it is possible to do it on the TSX, but having two plug wires crossed on cars that have plug wires can cause a sharp drop in mileage; as well as power.

8) Is it possible you have a small hole in your tank or fuel lines? Is there a fuel filter than could be leaking? Can you smell gasoline fumes inside the car.

You should have noticed a very sharp loss of power, especially when accelerating. But, your post made no mention of it. If there is a noticeable loss of power, then take that approach with the dealership rather than the mileage approach.

 

Dealer called me today. They filled the tank and drove until they had about 1/8th left. I forget exactly how many miles he said he was able to drive but it was over 400, and even if the tank was empty, 400/17 = 23mpg. So basically they're not getting 14MPG when they drive it.

Maybe I got a bad tank of gas, 3 times in a row? Seems pretty damn unlikely to me, especially since I went to different stations...

Anyway, they didn't charge me for looking at any of this, they even paid for the full tank of gas they drove. The car is at about 18.5k miles and I hate taking it so I'm having them do the 20k service too.

 

Check your Advanced Trip Computer's History for your last fill up. It will tell you your average speed and estimated time the engine was running. I do a lot of city driving so I typically get anywhere from 19 to 20 mpg, but that is also with an average speed of 20 mph and 11+ hours. Sitting in traffic or waiting at traffic lights are going to kill you average mpg.

A gas tank used on 100% highway driving ussually gets me around 29 - 30 mpg.

 

Got the car back, the navi trip meter said 32MPG! Holy crap, I've NEVER had any MPG that high before...

I guess I'll drive it some more and see what happens...

 

My car is weird.. I drive mostly city so I barely average 18 to 19mpg.. (no matter how light footed I drive)...but when i do a lot of highway miles I would get 30+mpg. When I went away to PA for the weekend, I averaged 35mpg. I wish I could get higher in the city.

 

So I've had the car back for a day now, and I get really shitty mileage with city-only driving.. like 19MPG or less. Highway driving gets high 20s.

So less than 19MPG city driving, no matter how light footed I am, is normal for this car?

 

In just one day, how many miles have you put on it in the city? On the highway?

Why do you now get 19 MPG, but only 14 MPG before taking the car to the dealer? Did the dealer put some air in the tires? Did the dealer adjust the computer to lean the mixture? I would be interesting in knowing -- just what did the dealer do to improve milage by 5 MPG? That is a significant increase.

In any case, 19 MPG is poor, unless you spend a lot of time in traffic that is stalled (i.e., a slowing moving parking lot). I have not seen anything less than 25 MPH with my TSX.

In any case, I suspect you are on your own. I don't think you can expect the dealer to do anything else giving that they have already established that the car is preforming as expected (at least, in their minds).

 

What grade of gas did the dealer put in for the test, 91 octane? When you got your car back, was the tank empty and what grade of gas did you put it?

 

The deqler did absolutely nothing except wash my car (they do that every time you bring it in). When I first got it and drove home it got 21.3, now its getting 19, so it's slowly dropping just like before. I wouldn't be surprised if it eventually reaches 14 again. This is just city driving, mind you. I thought this car did better in city driving.

Oh, I almost forgot, I asked them to do the 20k service, too. So they rotated the tires and changed the oil and inspected some stuff. But this was all after they did the mileage test.

 

The dealer filled the tank with 91 octane and drove it until the warning light came on. I haven't put any gas in it yet. I just drove hom from work one day (about 6 miles) and went to get a pizza today (about 6 miles). Before I went home from work, I reset the trip computer.

I've never put anything in other than 91.

 

Wow! I am gonna go wash my car -- right now.

irq, you absolutely can not check milage with a 12 mile trip. The only way to check mileage is with a fill-up and then another fill-up with a significant number of miles in between.

I can not make any sense out of your experience. You get 14 MPH and the dealer gets 30 MPG -- without changing a thing. And, you report no loss of power.

One final suggestion. Fill up the tank with gas from a known brand (Shell, Texaco, Amaco, Exxon, etc.), record the mileage, and then hand the keys to a trusted friend and have him take a trip of not less than 200 miles with the car -- or even better let him drive your car for a week while you drive his car for a week. Tell him to drive as he would normally drive. What mileage does he get? I would be very surprised if his milage wasn't close to what the dealer got.

There are only two things that could be causing very poor gas mileage. And, one of them is the car. The dealer has determined, at least to it's satisfaction, that it is not the car.

You said that no can get to your gas tank. But, right now, that appears to be the most likely scenario.

 

Continued from post immediately prior:

You said that no can get to your gas tank. But, right now, that appears to be the most likely scenario -- ignoring the fact that the trip computer is showing 19 MPG. The next likely scenario, in my mind, would be driving habits. What car did you drive before you got the TSX? Are you accustomed to pushing the throttle to the floor board? Was it a car that produced a lot of engine noise? Driving habits would show up on the trip computer and explain the indicated 19 MPG.

 

I used to drive pedal to the floor all the time when I commuted 60 miles a day down stop and go freeway traffic.. and I got 20mpg then. Now I drive extremely easily 12 miles a day, city-only traffic and am getting much lower. I'd like to blame my driving habits too but you'd think pedal-to-the-floor stop'n'go would be worse than super-casual suburban driving.

I typically use Chevron gas but since I've been getting this crappy mileage I'm trying other places just in case it matters.

I just filled up at a 76 gas station. $3.25 a gallon. I paid over $40

 

I am going to agree with driving habits as the problem. I have never gotten any less then 24mpg and that was all city driving. I am averaging 29+ for all miles driven.

 

I think some of you are missing the point.. especially the last post. 6 weeks ago I was getting 20 to 24 MPG in all city driving. Now I'm getting really low. I didn't change anything, including my driving habits.

 

It is either the car, the driver, or someone taking gas out of your tank. If you allow someone else to put 200-300 miles on the car, then you would have a good idea. Do you know anyone else that has a TSX that you can trust? But sure to give them a copy of your registration.

If they get between 14-19 MPG, then it is the car. If they get 23+ MPG, then it is either your driving or someone taking gas out of your tank.

There is no way that a car that generally gets 25 MPG to drop to 14 MPH, or even 19 MPG, unless:

1) It is driven very aggressively
2) There is a very noticeable loss of power (engine problem or excessive drag)
3) There is a loss of gasoline

What RPM's are you at at 60 MPH? If I recall correctly, you should be around 2200-2300.

I am most interesting in knowing the explaination when it is found.

 

Something must be seriously wrong with my car then because i barely average 19mpg with mostly city driving. I have a little under 6000 miles on my car, and I always put premium gas in my car. In fact, the mileage has gotten a little better because when I first got the car I was averaging 16 to 17 mpg...

My last gas mileage history as per the trip computer was 19 mpg with an average speed of 19.3mph. I'm amazed that you guys can get at least 20mpg with 100% city driving.

My car gets terrible mileage with only city driving.. less than 17 to 19mpg.
With A LOT of highway milage I can get in the high 20's to even 30's.

 

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You can not trust the navi trip.... do the math the navi in my car is always 7-12% higher then actual.

 

It depends a lot upon the city and your driving habits. In Atlanta, drivers tend to race from one traffic light to the next -- as they do in NYC. But, in Asheville, the pace is much slower and you don't have to stomp on the gas when the traffic light turns green in order to keep your place in the traffic flow. It is so obvious after living in Asheville for a year at how impatient drivers are from Atlanta and other big cities. They stomp on the throttle at one traffic light only so that they can stomp on the brakes at the next traffic light.

I do no 100 percent city driving (if you call Asheville a city) and I use SS 99.9 percent of the time. The lowest milage I can recall getting was 25 MPG. However, I am in the mountains and that doesn't help gas milage. But, I also make use of the hills. There are a couple of four mile stretches near me where the car will coast at 50 MPH in neutral -- and that is what it does on each occassion. Now, I wouldn't be surprised to see 19-20 MPG if I was driving in the Atlanta area for the full tank.

The EPA figures are 23/32 and I would expect to see different drivers in different locations getting a variance of plus/minus 3; especially for the city milage.

 

I noticed yesterday when I filled up that my gas mileage was way way off after driving a bit.

I think that it calculates the your mileage by the amount you put in since I filled up way earlier than normal.

 

almost every time I have been into the dealer I say something about it being off and they have no real explination for it..... does anyone on here know how it is calculated?