mdb20

I have a 1995 Integra LS Sedan with a B18B1 and a 5spd man. I used to get 31-33+ MPG on the highway in my car about a year ago, while using the AC. Lately, I've been getting significantly less than that. Last weekend, I got 28.5 mpg on a 275 mile trip. I was only driving 65-75 mph the whole way as well, but it was all highway miles. It was raining hard for 1/4 of the trip and for 1/2 of the trip I was battling a 20-30mph headwind. I also had the AC on for the majority of the trip and had about 500lbs of people, gear and dogs in the car including myself.

Here is a list of things that I've thought about and/or checked: tire pressure 33-37psi, new air filter, tires balanced, wheels aligned, proper oil weight, newer thermostat and radiator and good coolant level, new distributor cap and rotor, good spark plus and wires, no excess weight in the car, valves recently adjusted and timing belt replaced, 90K and 105K tuneup, fuel injector cleaner used a few times a year, new fuel filter. The wheels and tires are new and the tires may add some rolling resistance since they are Kumho "W" rated and have a "AA" rating for traction. The wheels however are very light. They are 15" Konig Feather's and weigh around 11.5-12lbs each.

I know there are a million things that can cause bad mileage, the most important being driving habits. I've thought about the O2 sensor, but Honda doesn't have a recommended replacement time unless there is some sort of trouble code or check engine light triggered. The same went for the fuel filter, but I replaced that myself anyway, since its a cheap part and fairly easy to do. I've even tried to remove the O2 sensor with the special socket from the auto parts stores and I can't seem to get a good leverage point on it with either a wrench or a ratchet without removing the headers from the car all together.

Any ideas anybody? Any help would be great. I've thought about a compression check or power loss, but the car seems to have plenty of power and doesn't feel much weaker than it used to, if at all.

Sorry for the long thread and thanks for any ideas and or help guys!

Khazzy

octane levels in gas nowadays but could be a car problem, sorry if that isnt any help, but my gas mileage has gone down as well....and my car is clean as a whistle 99integra gs

TheOtherDave™

When was the last time you physically checked the spark plugs?
If you're using the OEM NGK copper plugs, they only have a 30K lifespan.

I had the same precipitous drop-off in mileage last year.
At it's worst, my city only mileage hit 20.25 mpg.

Turns out the plugs were being fouled by an accumulation of oil.
Changing the seals on the spark plug tubes stopped the fouling problem and with a new set of OEM plugs, it solved the gas mileage woes immediately.

Khazzy

now that i know this as well...im going to the auto store haha, thanks bro

Lynxs1981

With a headwind like that, that kinda mileage doesn't sound that far off.

Spec R

yep, i'm with headwind and sparkplug solutions.

lots of mileage threads popping up in all the forums i'm in lately.

mdb20

I just got done checking the spark plugs. The gap is ok and there's no oil or any other accumulation on them. I can't remember when I changed them, but it's definitely been less than 30,000 miles ago. Probably closer to 10,000. They were a little grayish white on the electrode, due high heat and high throttle most of the time, but so are all of my plugs when I change them, instead of the "almond color". The car idles fine, and there is no pinging, knocking or hesitation under acceleration, so maybe the plugs/wires are good to go. When I took the car to the dealership to get the 90k & 105K done, I knew more about cars then the service advisor. Maybe this is because I got my BST in Automotive Technology, I don't know. He was little help when we talked about fuel economy, etc. I've talked it over with a classmate of mine from college and he couldn't think of too many other things that I haven't checked. At this point, I may try to email some of my Auto Tech professors who've been working with mechanics longer than I've been alive. Thanks for the help and any other ideas would be appreciated!

Mark

Khazzy

can i go back to the diluted gas we now have due to high demand for cheaper prices?...to me it makes sense

octane levels in unleaded regular used to be like 87, now they are 81, crappy gas means its well...crappy, just my thoughts

mdb20

I just got done checking the spark plugs. The gap is ok and there's no oil or any other accumulation on them. I can't remember when I changed them, but it's definitely been less than 30,000 miles ago. Probably closer to 10,000. They were a little grayish white on the electrode, due high heat and high throttle most of the time, but so are all of my plugs when I change them, instead of the "almond color". The car idles fine, and there is no pinging, knocking or hesitation under acceleration, so maybe the plugs/wires are good to go.

When I took the car to the dealership to get the 90k & 105K done, I knew more about cars then the service advisor. Maybe this is because I got my BST in Automotive Technology, I don't know. He was little help when we talked about fuel economy, etc. I've talked it over with a classmate of mine from college and he couldn't think of too many other things that I haven't checked. At this point, I may try to email some of my Auto Tech professors who've been working with mechanics longer than I've been alive. Thanks for the help and any other ideas would be appreciated!

Oh, in regards to the octane rating of the fuel, I was reading an article in Popular Mechanics regarding the octane of unleaded fuel. It was stating that the minimum octane fuel allowed to be sold in the US is "85" and that was only in high elevation areas such as the Rockies, etc. Everwhere else has a minimum of "87". Now, individual proprietors could "water down" their gas as many have been known to do. I would notice a significant loss in power, as well as the mileage, due to the ECU retarding the engine timing due to the sub par fuel octane rating. Who know's.

Mark

Fuse

What are you asking? How old is you o2 sensor is it is not reading right it will richen or lean out the mix. Stay of the throttle, over inflate your tires, align the car, get low roiling resistance tires, advance your base ignition timing, loose dead wight in the car, clean injectors or get new ones to get lower mpg.