98 Q Terrible Gas milage

[QFourFive]

I am experiencing terrible gas mileage with my 98 Q45. When I got the car the gas mileage was pretty decent, but last month I got a new fuel filter put on at the dealer (it was a Wix fuel filter) and since then the gas mileage has been terrible.

I filled the tank up and it only went about 180 miles. The estimated city fuel economy is 16mpg, and I'm only pulling in a little more than 8mpg.

Please, I need help with this because its killing my wallet.

[maxnix]

I seriously doubt the dealer would use a Wix fuel filter. But who knows?

We need a maintenance history to help you.

Ethanlolized fuel?

[tfvesquire]

I know this sounds far fetched, but it is possible your mechanic installed the fuel filter backwards and/or kinked on of the gas lines when then installed the filter. If that is the only thing that was replaced when your MPG suddenly went down, then I would start there. The choice of fuel cilters probably won't cause a dramatic decrease in mileage per tank.

Good luck.

[Victor]

Getting less gas to the engine wouldn't make gas mileage go down would it, just make the car perform worse. More likely a gas leak from an improperly tightened connection, do you smell gas? Or maybe the mechanic broke something or loosened an electrical connection while working on the engine.

[tfvesquire]

Getting less gas to the engine wouldn't make gas mileage go down would it, just make the car perform worse. More likely a gas leak from an improperly tightened connection, do you smell gas? Or maybe the mechanic broke something or loosened an electrical connection while working on the engine.

Good point. I guess I was thinking about decreased performance levels with constricted gas flow versus lower mpg. Possibly KS or coil problems or even injector problems if you don't find any leaks. Faulty injector could be dumping gas into the cylinder. Hope you find it out fast. Gas prices are too high to waste any 93 octane!!

[Skibane]

How well does the car run? Have you noticed any drop in power or smoothness since the filter was replaced?

[QFourFive]

I bought the Wix filter myself and took it to the dealer. Is Wix a good brand?? Since I got the filter changed the car feels pretty much the same, a slight loss in power/ acceleration, and the gas pedal felt softer. Had to press it harder than usual to accelerate.

[QFourFive]

Come to think of it, I was cleaning my car today and when I was cleaning the back rear wheel (near the fuel filter) I did smell gas. I kind of dismissed it because I thought I was being paranoid because my gas problem.

[QFourFive]

Oh, and I don't have the vehicle history past May 2009. Since then I cleaned the throttle body, put in an K&N Air Filter, new rotors and brake pads

[maxnix]

K&N filter could well be your problem.

Putting an oiled filter element in front of a hot wire MAF sensor is not a very wise thing to do.

All Infinitis have a dealer performed service history. It is the owner's responsibility to obtain it, preferably prior to purchase as part of the pre-purchase evaluation.

Substituting after market parts for OEM willy nilly is a guaranteed to have a short but painful and expensive Infiniti ownership experience.

Read the previous posts here first and save money, improve performance, and enjoy your car.

[QFourFive]

Thanks. I just finished reading up on past posts and I think I'm going to replace the K&N with a new OEM air filter. Is the brand of the fuel filter ok, if not which type should I get?

And are there any modifications I can do to increase my acceleration because my car accelerates embarrassingly.

[maxnix]

No, not really except to rehabilitate it.

Read Skibane's excellent post on auxiliary ATF cooler hose routing.

It's more of a cruising car. Honda V6 will hand you your lunch all day from a standing start. But your top speed is 145 mph.

[QFourFive]

What performance change would I experience by installing an ATF cooler?

[qship96]

None. Possibly LONGER transmission life depending on operating conditions.

[BadQ45t]

You did not mention how many miles you have on the car. That is your first thing you need to post.

Second, stop going to the dealership, this is way too old of a car to being dealing with them. You need to find a good aftermarket mechnic in your area that knows Nissans/Infiniti's and get him to spend the time on figuring out if you've had a 60k service done. You would need new plugs, flush all fluids, etc. If in fact you do not know this history, I would give the car a full check over by having the mechanic examine all the fuilds and if there is any doubt flush everything. It might cost you 1200-1500 bucks at the end of the day to flush transmission, rear end, brake fluid, power steering fluid, and coolant. Get new stock NGK spark plugs (no aftermarket Bosche or anything like that, these cars hate those) and see where your at after that.

If your over the 60k mark your also probably going to have to look at your tension rods, they are usually shot by 60-70k and make the car have much more front-end play and shocks/struts replacements. I used KYB SR Specials which rock in comparison to stock.

Find yourself a good well recommended mechanic locally, you cannot afford the dealership for anything but oil changes and an occaisional over-the-counter part.

Post up where your living and somebody on the board will probably have a line on a local good independent mechanic.

[maxnix]

http://www.jerrytucker.net

Go there!

[BadQ45t]

Looks like the dude lives in Virginia, that might be a long drive to San Diego

[QFourFive]

My car has 90,300 and I'm located in Richmond, VA.

[maxnix]

Looks like the dude lives in Virginia, that might be a long drive to San Diego

Oooops, I thought it was El Granada. What happened to Half Moon Bay?

For the poster, try T-3 in Atlanta.