I purchased a 91 q45 because my Nissan Altima was hit from behind and totaled. Of course I know that the Q45's gas mileage wouldn't compare with the Altima, but I think this one is still using way too much gas. For example, I filled up the tank on Monday. I always reset my trip odometer to "0" so that I can review my miles. Well, today after traveling 213 miles between Monday afternoon and this morning, I am on empty again. In other words, it looks like I am only getting about 12 miles per gallon..OUCH!!! I did notice that the trunk area up from my exhaust pipe keeps getting this black soot on it coming from the pipe. I am not an expert on these things, nor have I ever worked on fuel problems before. I was just wondering if anyone could tell me what could be causing the high gas usage. Also, I need to know if the black soot coming from the exhaust pipe has anything to do with it. I only use 93 octane gas in the tank. I use either BP or Chevron gas.

Any incite on the fuel problem will be greatly appreciated. Thanks in advance to all that respond.

new to the car = heavy footmay need o2 sensorsblack soot is just that the car is running Rich

Welcome to NICO, you should be able to find anything you ever need to know about a Q45 on here.

Check replace the MAF, plugs, knock sensor and o2 sensors and you may see some improvement, but mid to low teens for city driving (especially with winter mix fuels) isn't really that far out of line.

Do you know if the (plastic backed) timing guides have been replaced? If not, you may want to find out before you start the car again. Sorry if that sounds alarmist.

Or before you spend money on other parts.

Chain guides explaned.zerothread?id=25201

And yes, NICO is your one stop shop for all the info needed. It has helped me keep 2 Q45's on the road now. Welcome.

Chevron > BP

Calculate your actual mileage adjusted for tire size.

Please also post a maintenance service history.

Q45 owners know never to run their tank below the ¼ level.

Welcome in and start reading.

Save up about $4~5,000 along with a six pack (to ease the pain) and take it to T3 Auto Mechanics in Atlanta. They will do it right the first time and tell you exactly what you need and don't need done.

May want to check the ECU (computer) for any codes that may indicate something may need attention. BTW - I usually get 400-420 miles from a tank (not all easy miles either). Hope this helps

Dale

Thanks Dale. Matter of fact, thanks to all that have replied so far. Please forgive me for being such a novice at this. But how do I check the ECU computer? Also, most of the miles that I run are essentially highway miles.

Stop by T3 Automotive LTD in Decatur [2346 lawrenceville highway 3 miles inside I285] they will check codes for free with Consult.Tell them I sent you. 404 633-7722.

I not sure using fuel gauge is at all [anywhere near] accurate what was full to refuel amount/vs mileage.

Black soot on bumper usually means MAF connector problems!

I put a little over 18 gallons in on the initial fill up. When the "low fuel" display came up, I put a little over 19 gallons in. Im not of the full capacity of the tank. I think its listed at 22 gallons.

Just go to home page and click on Infiniti ECU Codes under the article section. It will help you.

Or... do the smart thing and accept Q45techs invitation. You will not receive better more honest advice than that which T3 will offer you. If Dennis says stop by... you should do so.

Also... welcome to NICO from a fellow noob. I promise you, you will find everything you would ever want to know (and probably some things you don't want to know) on these forums.

i agree,,,,,do what dennis (q45tech) suggested and stop by T3. as a noob you will probably be like i was and overwhelmed by all the possible causes of every little thing. reading the codes will narrow things down in a hurry and one of their tech's can probably poke around under the hood for a few minutes and let you know about the general shape of things. if you plan on keeping the car for any amount of time (and it sucks giving up a Q!),,,,,check into the chain guides. that was my first "upgrade" when i bought my 90Q. WELCOME,,,AND YOU FOUND THE RIGHT PLACE FOR ALL THINGS Q!!!!!