Poor Gas Milage help

[miksax]

I have a 91 lx that has 120k. Its all stock except for a K&N filter, flowmaster mufflers, and the timing was raised to 14. I have been driving the thing like a grandma and getting horrible gas milage (11 MPG). I took the car in to be diagnostic tested and they recommended a service that involves high-pressure cleaning of the throttle body and fuel injectors. They said the air filter, and cat-converters are fine and no codes came up on the diagnostic test. Are these people feeding me BS or is this a plausable fix? The service costs $130. Thanks for anyone's help, I'm kinda new to this forum thing.

Thanks,
Mike

 

[tjm73]

Is the car modified at all? You should easily pull 20+ mpg. Are you city driving all the time? Or are you highway driving? Or, is it a mix? What kind of mix, if so?

I got a bunch of mods including 3.73's and get a combined mpg of about 18-19 mpg.

 

[desertdog]

My gas mileage took a sudden dive last fall,down to about the number your at right now.Changed the O2 sensors,and it returned to my current mileage of about 19-22 mpg.Hope this helps.

 

[darthcual]

Barryman B12 will clean the fuel injectors out. If not, time to get new ones. Do you have new spark plugs and wires? New fuel filter? You'd be suprised what a little maintenance will do for your gas mileage. Has your K & N been cleaned in awhile? Just some suggestions. Dont give money for that service! These are all things that can be done with some patience and a few hand tools. Good Luck!

 

[mob]

grrr, i have bcam, o/r h, and advanced timing and im getting 12.7mpg, how much would a k&n filter help? is it the cam?

 

[dkins419]

ahhh bad gas mileage. I just got my car, filled up 4 days ago, and went 100 miles and i am a line below the half tank. Recently did an air filter, spark plugs and wires, and today im changing the o2s. Hopefully thats what it is.

 

[NakedRaygun]

You can't clean your own TB? NEW 19lbers would be cheaper at that price. Try getting a new IN-LINE fuel filter/ getting the rails cleaned. See if the MAF sensor is all gacked up too.

 

[machfelon]

I have a 2004 Mach 1 and my gas mileage is bad too! At 200 miles Im on fumes!! Sometimes dont even make that!!

 

[mob]

You can't clean your own TB? NEW 19lbers would be cheaper at that price. Try getting a new IN-LINE fuel filter/ getting the rails cleaned. See if the MAF sensor is all gacked up too.

i cleaned my t/b and maf and set my tps and car was running better but that was before my 12.7mpg so i dont htink it helped much unless i was at like 8mpg

 

[sunil6784]

Sorry for interrupting, but how do you know when you're O2 sensors need to be changed ?

P.S I did a full tune up, plugs, wires, cap and rotor, fuel filter, cleaned throttle body, cleaned K&N, a bottle of injector cleaner, and my mileage went from 16 on the highway to 20, and from 13 in city to 16.5 in city. The little things do matter.

 

[NakedRaygun]

Sorry for interrupting, but how do you know when you're O2 sensors need to be changed ?

P.S I did a full tune up, plugs, wires, cap and rotor, fuel filter, cleaned throttle body, cleaned K&N, a bottle of injector cleaner, and my mileage went from 16 on the highway to 20, and from 13 in city to 16.5 in city. The little things do matter.

Most over the counter injector cleaners are as strong as old coffee.

 

[Slo 5.0]

i only get 12 mpg... i hate it, i cant afford it!

 

[Retro10]

My 93 gets 11 mpg in the city and only mods are K&N and BBKhigh flow hpipe with cats and the flowmasters. Now when I drove it to KC for a show I was getting nearly 26 mpg....so yeah that big of a difference
11 mpg city and 26 mpg highway...no clue as to why that big oj jump?? then I noticed on the way back its starting to burn oil..great!! I wonder why that started all of a sudden?