I'm getting bad gas mileage so I started to change plugs, wires, fuel filter, pcv, etc. Changed the plugs(NGK) and now when accelerating the car seems like it has a misfire. Never did this before? Didn't hinkk you needed to gap NGK plugs, so I didn't. checked the gap the other day... Looks good(.44). At a loss here???

Also, the 98 civic hx, 5-speed according to everthing I've looked at as far as EPA goes should be doing 29-30mpg in town and around 39 on the highway...

Gas Mileage of 1998 Honda Civic

My car is and has been doing 25 on the interstate. what the hell???? Don't expect it to do factory specs due to the age and having 134K but, come on. My Evo does 23-24 on the interstate. should I go get a compression test done? Any ideas would be greatly appreciated.

 

lol yeah that does suck...what is the code on the
check engine light??

 

If it just started to misfire, try putting your old parts back on. Start with the wires, as some aftermarket sets are junk. Could also be a dud cap or rotor. The gap should be .044 but it's not absolutely critical.

Wrong timing will ruin gas mileage. You need a timing light to set it. An old car can still get good mileage unless the engine is completely worn out. You'd notice that by it burning a lot of oil.

 

also make sure the plug wires are all the way on... bought a cheap set when i first got mine, and the damn things liked to pop off... took them back to get "the next step up" (as far as price goes) and they worked great

 

for gapping spark plugs look under you hood there should be a lil chart telling you what to gap your spark plugs at..

 

I don't think the engine is worn out... Not burning oil and seems to run really good besides the new misfire problem. Getting a compression test done Thursday, will have the timing looked at also. I will put the old parts back on one at a time and see what happens.

 

also, no CEL light is on.