sucky mpg =[

[cvc7chris]

i checked my mpg using 93 and 87 oct gas. heres my results
(CITY Driving)
87 octane = 20.3918 mpg
93 octane = 23.0821 mpg

and i just replaced my spark plugs (ngk g powers) / wires (autocraft)/ dizzy cap / rotor earlier and i'm going to re-check it. although my spark plugs weren't THAT old. my tire pressure is at 35 psi on all 4 tires. i have ran the gumout fuel injector cleaner before i start checking my mpg. i'm probably gonnna seafoam it to clean it out gooood.

so my question is. does it really help to run 93 octane? or not. and what else can i do to improve my gas millage i do have 3 10's in my trunk too . and i don't go past 3 or 4k when i'm shifting i drive slow all the time and chill. but i wish my mpg was at least 25-30mpg

[LeeForget]

the increased MPG with the higher octain could simply be because it has many cleaners in it compared to the cheaper gas.

[foamypirate]

Change your fuel filter and do a valve adjustment. These two steps are often overlooked, and can result in a decent fuel mileage increase.

[cvc7chris]

Change your fuel filter and do a valve adjustment. These two steps are often overlooked, and can result in a decent fuel mileage increase.

fuel filter was done in like april of this year

and i do need my valve adjusted just don't know how to do them myself

the seafoam might help since my cars got 293k on it

[illestatus]

clean your egr, intake filter, and iavc(how ever you spell it) im getting not so good mpg myself, i think i need another tune up soon since i been driving my car often

[mtnbikaah]

leak in a fuel line?

i have a leak in my air return line from the tank to the filler. when the tank is full, or filler neck leaning downhill, it leaks...

but im still getting 25+mpg...

[h22sparkle]

You cant expect the car to give you alot of mpg if its old. If you want more mpg for your dollar you got to get a newer car. The one that your driving is dated. The choice is yours if your really trying to save money.

[Losiracer2]

how old is your o2 sensor? Even though the CEL isn't on, the O2 sensor is also considered a wear item and should be replaced, prob. every 90k I'd assume. The CEL only comes on when its completely broken and not functioning, but the parts can still wear out.

[anythingfast]

You cant expect the car to give you alot of mpg if its old. If you want more mpg for your dollar you got to get a newer car. The one that your driving is dated. The choice is yours if your really trying to save money.

I would have to disagree with this. Just because it's "old", high miles shouldn't cause this drastic of a difference. And the valve adjustment is super easy. If you can change a valve cover gasket and you have a decent mechanical understanding you should have no problem. Both of my CB7s had over 200,000 miles and both got the same mileage (23-32mpg)

OP, how many miles are on your car? Auto or manual?

[jdm_inspired]

how old is your o2 sensor? Even though the CEL isn't on, the O2 sensor is also considered a wear item and should be replaced, prob. every 90k I'd assume. The CEL only comes on when its completely broken and not functioning, but the parts can still wear out.

This guy read my mind.

[accordkid16]

my cb7 was getting around 32mpg and i bought a cheap shortramair intake from matrix off of www.summitracing.com and now getting about 36mpg, nice sound and a good acceleration punch

[Shag Wagon]

Yea I am getting 24 mpg but I run a delta 272 cam and a gas guzzling tune. I wish I could get at least 28-30 but I know that will never happen with a 3000lb 4cyl auto. I would definately replace that fuel filter if you havent done it recently. I probably need to do mine since it has been in there a while. Also an OEM O2 sensor could be in order for ya.

[HondaFan81]

Full tune-up should be regular maintenance (cap & rotor, wires, plugs, fuel filter). Your engine should have base idle set properly and base ignition timing. I just created DIY stickies for that, many people do not have it set properly. Set your valve lash adjustments every 15-25K depending on motor.

Make sure your TPS is working and set properly. Replace the IAT (intake air temp) sensor, as they are old and critical to ECU. Make sure your O2 sensor is working properly. Make sure of no fuel leaks, this should be very obvious and cause for extremely low gas mileage.

Is your clutch (manual tranny) obviously slipping or not?

Keep up with your oil changes. If you are burning oil excessively (1 qt+ every 3K miles) and while engine is running you notice smoke coming out exhaust, smells like oil, then you need to recondition your head (avg. $150-250). This includes cleaning, resurfacing, new valve seals, valve job. The valve job and valve seals are KEY for good gas mileage.

Also, consider if you have oil in your spark plug tubes, that should be fixed (O-rings under rocker arm assy, refer to DIY).


Real World Example:

My brother has 1990 Accord EX sedan manual/5-spd that I've done ALL tune-up/maintenance on the motor, even a fresh timing belt job, water pump, valve lash adjustment, front engine seals, changed all fluids, etc. His motor has 368K miles and runs smooth and great. The clutch was new OEM and is only like 1-2 yrs old. I drove his car a few days doing maintenance and studided it. It gets 27.2 MPG, mostly HWY driving. I do NOT consider that to be top notch either (high standards)!! However, it BURNS 1 qt. of oil every 400 miles!! I have my wife start the car, engine was cold, I watched the exhaust. It smokes constantly while running and it smells like oil.

My bro just purchased the necessary OEM replacement parts (headgasket, intake & exhaust manifold gaskets). I'm reusing other gaskets, as they were just replaced. We are getting his cylinder head reconditioned (cleaning, resurface, valve seals, valve job) and I'm doing the reinstall. I will obviously redo the valve lash adjustment as well in doing so.

I guarantee it will get better gas mileage, watch. I predict 30+ mpg with 368K miles!! If I remember, I'll post back.

[cvc7chris]

i got a 293k and i put a new o2 sensor in about 4 months ago.

so that couldn't be it. i just seafoamed the car yesterday and we'll see what the mpg is now.

[Losiracer2]

i got a 293k and i put a new o2 sensor in about 4 months ago.

so that couldn't be it. i just seafoamed the car yesterday and we'll see what the mpg is now.

I'm gonna have to put the blame on high mileage. 293k is quite a lot of miles especially if you haven't done a rebuild to the head like Hondafan81 said.