I have recently been getting really shitty gas mileage, less then 200 per tank. I been unable to find the problem. I did the full-tune up with all OEM parts, even the plug wires and spark plug (NGK plantinum). Pour a bottle of Chevron fuel system cleaner, still didn't fix the problem. Did the compression check and 220+ on all 4 cylinder. The engine is bone stock with 120k miles, it's a 94gsr, no check engine lights and it idles fine.

I thought it was the 02 sensor but I pulled the spark plug and looked at the tip and they all looked fine. A dark brownish tan look on all of them, so I need the air/fuel mixture was correct, thus meaning the 02 sensor is still good. The only thing I havn't done is the valve adjustment but I bought it to a mechanic near my house but the guy said I didn't need one because the valves weren't tapping.

I am pretty freaking pissed at this point and clueless as to what may be the problem. Any help will be appreciated.

 

is your tire pressure ok (35psi)?

 

You might still want to check the O2. I have a universal one that I can sell to you for 50 shipped.

If its not that, check your brakes and make sure they arent sticking. I know the rear calipers have been known to stick.

I had the same problem as you did with my 96, i did everything possible to fix it except the o2, but i totaled it before I could replace the o2.

 

do you redline it in everygear or somethin?

I use to get between 240 miles on a tank in my LS. i checked the air pressure in my tires and it was 18 in the front right and 22 in the front left, rears were both at 26. i changed them to 33 on all 4 and now i get about 320-345 a tank with the occasional 1st or 2nd gear redline.

-Ryan

 

my R gets only about 200 per tank...actually really low 200's so your not alone...it sucks especially with gas prices the way they are.

 

oh yeah, and my mileage was with 3.5k-4k shifts, hitting vtec maybe once a week

 

u may have dont this but it wasnt mentioned, the fuel filter.
i have a 94 rs with 130k miles. i usto get about 240 a tank, changed the fuel filter and now i get about 300 a tank.

 

Air pressure on tire is ok, I always check them once a week and have them on 32psi. I DON'T DRIVE LIKE A MAD MAN, I rarely put the car into v-tec and shift around 3.5-4k. Idle fines and at 800rpm, I check the timing and it's 15degree, so that's fine. The car's engine is bone stock.

I did the fuel filter, did the full tune-up with all OEM parts.

Spark plug wires
Spark plugs (NGK plantinum)
dis. cap & rotor
fuel filter
air filter

-also used a bottle of Chevron fuel system cleaner.

-Also changed my coolant and inspected it for oil to see if it might be a blown headgasket but no oil in there, so that's fine.

Did a compression check and got 220+ on all 4 cylinders

According to my local mechanic, I don't need a valve adjustment because there wasn't any "tapping noise". I highly doubt it's the 02 sensor because I don't have a check engine light and my spark tips were all good, they were a darkish brown/yellow color. You tell the if if your 02 sensor is bad or not by pulling out the spark plug and examining the tip.

Pretty f@UCKING pissed off cuz I can't traced the dam problem. And gas prices are CRAZY at $2.39-$2.49 for superunlead.

 

seeing as everything else is fine, i would check somewhere along the line of a fuel preassure regulator. smell the exhaust when the car is warmed up, does it smell like to much fuel?
or some other part that controls fuel, maybe the fuel pump is dumping to much fuel, have you noticed the car to be faster, as in larger fuel injector upgrade?

 

check for leak's?

 

do you avoid highways? do you turn your car on and off a lot?