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DSMHondaGuy 01-11-2018 08:17 PM

Base line results for 322,000 mile 98 Honda HX 5 speed

Not a bad start. First goal, 40mpg, should be doable, will make a few small changes this weekend, top it off and see where this next tank of fuel puts me. I'll post pictures and details in this thread later this week.

jcp123 01-11-2018 08:17 PM

What's your commute like?

DSMHondaGuy 01-11-2018 08:34 PM

A good many elevation changes and corners the whole way just about from my rural location into the city of Athens. It's mostly "highway" miles. I'm very good at timing lights properly to keep momentum as well.

With winter weather, wet roads and unknown tire pressure, the accelerator pedal issue, possible coolant sensors reading low (gauge seems to anyway not sure the engines actually over cooled but I have my suspicions given the amount of time it takes to get hot air from the heater seems a bit longer than it ought to be) indicating that perhaps the thermostat has either been removed (that's stupid) changed to a lower temp (also stupid) or stuck in a open state and a few other very minor things I think that number can easily come up some, especially this summer.

Stopped today at the local parts store and had them scan the ECU for codes, clean no codes. Excellent. (there was no CEL but sometimes minor codes don't seem to throw a CEL so I wanted to check anyway)

California98Civic 01-12-2018 12:07 AM

Very nice. I have a 98 DX with 255,000 miles. You'll get wy higher numbers than 38 if you keep to it. Great little go boxes, these old Civics.

Xist 01-12-2018 03:09 AM

Do you have a Fumoto Quickvalve? My oil pan stripped the first time I changed the oil. I replaced the pan and installed a Quickvalve. I can pull the filter from above and drain the oil without tools. I cannot imagine oil changes being easier.

Replacing the oil pan was a chore, though. The torque specs of aluminum is not much lower than steel, but I have stripped two aluminum bolt holes while trying to be careful. I have not stripped any steel holes.

The oxygen sensors are prone to failure. Everyone says that only the factory sensors work and they are expensive, but you can find them for less than Honda charges.

I do not know that it is common with Civics, particularly HXes, but mine has low compression, and as far as I know, it did when I bought the car at 170,000 miles. That is pretty easy to check.

We always encourage instrumentation, which is more difficult with lean burn, but a $5 bluetooth OBD-II dongle and an old phone, or a cheap pre-paid one, can give you a wealth of information, plus you can read your own CELs. If you want to monitor your fuel economy, you need an MPGuino.

At some point I recommend removing the power steering belt, driving a tank, and then putting it back, so you can see if there is any difference. I removed my power steering and the extra effort when stopped does not bother me. It is supposed to provide a barely-measurable increase to power and fuel economy.

I love the HX wheels, but it would benefit from smooth wheel covers. Other members favor coroplast circles or pizza pans. I think pizza separators look better, but I did not like my attachment method. You could also put fiberglass resin on a cardboard circle.

I screwed a rolled-plastic air dam and grill block onto my front bumper, but I like Metro's air dam for his Miata better. He figured out how to attach it without putting holes in his car.

At what speed do you drive? If lean burn works, you should get better fuel economy at 65 MPH than 55. For some reason, I did not think my lean burn worked, so I drove 55 for a year or two. Then I drove 65 for a tank and had a definite improvement. Talk about regret! :)

I also saw a big improvement cleaning out my EGR passages, although my long-term data was confusing.

Daox sells shifter knobs with built-in kill switch buttons. He has different versions with more buttons, too.

Welcome and good luck! :)

DSMHondaGuy 01-12-2018 05:45 AM

I didn't know one of the criteria for it to go into lean burn mode was vehicle speed, I just figured it was based on throttle and engine load. Well I guess I may get to work a little faster today.

I have a compression gauge so I may get around to checking the compression this weekend as well, I have a Haynes manual for the car which shows for the SOHC D16Y5 engine "standard" compression (new) should be 184psi, minimum spec is 135psi.

Xist 01-12-2018 10:01 AM

I am sorry, I cannot find the information now, but as I recall, lean burn requires the engine be a certain temperature, and a certain RPM range.

DSMHondaGuy 01-12-2018 10:09 AM

I'll have to look into that.

Considering looking for a wideband capable of reading very lean mixtures, that or one of the scan tools that can tell me when the cars in lean burn mode.

California98Civic 01-12-2018 04:34 PM

Two good threads on how HX lean burn works:

DSMHondaGuy 01-12-2018 06:45 PM

Thank you for posting that, the first one gave most if not all of the information I was looking for.

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