Hi again

[upnsmoke]

Hi everyone. I haven't made any posts in about a year, so I figured I would re-introduce myself. I have been reading through the forums occasionally, just haven't had time to post. I have been working on my father's 99 Ex during the past week. Sadly, it is the only Civic in the family right now, though I do plan to acquire one of my own as soon as finances allow. I painted and installed a set of 15x6.5 junkyard wheels, amongst other things. As I have been driving the car around over a number of days, I noticed that the fuel mileage is disturbingly poor. I measured it as low as 19 mpg in the city. After driving, the engine oil smelled of gas, which is a bad sign.
What I have done so far:
changing oil frequently to prevent wear on engine as a result of gasoline contamination
replaced O2 sensor- upped mileage to around 24
checked map sensor, throttle position sensor, and intake air temperature sensor- all in spec
checked fuel pressure- in spec, changes quickly with changes in vacuum and does not leak down after engine is shut off, which would indicate to me that no injectors are leaking and fuel pressure regulator is functional
replaced plug wires, cap, rotor and coil- didn't change plugs as they looked fine, but did adjust gap to spec
cleaned air filter

The car has about 80k miles on it. It seems to run well. It idles smooth, the engine feels responsive and pulls hard, never stumbles or bogs. I don't think it is leaking gas anywhere, as I can't smell it nor do I see any on the ground. The check engine light is not on, though it does function. I would much appreciate any thoughts on what else could cause such a drop in fuel mileage. If I should post this elsewhere, feel free to let me know. Otherwise, I just wanted to say hi, and I look forward to talking to you all again.

 

[R3dline]

changed the plugs and wires? any other basic tune up parts, filter, fuel filter etc?

also what brand gas do you use? if you use cheap s**t gas, that will hurt the mpg, iv noticed a difference on my last car from when i would use say raceway, over using bp or chevron. the cheap gas didnt last nearly as long as the better brand gas

thats just my 2 cents

 

[upnsmoke]

R3dline, I have done all the basic tune up stuff. I also have noticed some weirdness with cheap gas. I witnessed a test of the alcohol content of several samples of gasoline. It has been several years and I don't remember exact numbers, but there was a significant difference between some brands, and between winter and summer blends. Some of those claiming to be "in the know" also say there are significant differences between different brands of gasoline other than alcohol content. In, fact they convinced me not to run 87 octane. Ever since, I have run 89 in all my cars that are rated for 87. I don't even remember what was bad about it, but I don't run it any more.

 

[mymmeryloss]

Have u tried lighting the changed oil on fire?

U might have a leak in your gas tank.

I also suggest a seafoam treatment!


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[upnsmoke]

Have u tried lighting the changed oil on fire?

Would this be akin to proof testing alcohol? I would think by the time you make a flammable mixture you are really in trouble, though I certainly don't know for sure. I do know that it doesn't take much gas in the oil to start wearing bearings out quickly.

I'm going to check closer for any leaks I could have missed tomorrow. I'm thinking it almost has to be running rich though. Besides the bad mileage, the plugs looked a little dark, and there is some black soot in and around the tailpipe. If I don't find any leaks, I think I am going to pull the catalytic convertor and put in a test pipe, which I was planning to do anyway, and use a wideband O2 to find out just how rich this thing is running and under what conditions.

 

[mymmeryloss]

Take a small amount and put it in a lid of a water bottle or something and see if it ignites


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[upnsmoke]

Well, I left the fuel pressure gauge on overnight and saw no significant leak down. That rules out a leak, unless it is the tank itself. If the tank was leaking, wouldn't it throw a code for evap emissions? I'm going to take a close look anyway, as soon as the rain lets up. It is becoming apparent to me that there will be no quick fix here. I think I will start a thread in Engine/ Drivetrain tech.

 

[mymmeryloss]

Ya start a thread with a more descriptive thread title...


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