Please Help Civic VX MPG

[robertsvx]

Hello,I'm new here and I have a 94 vx. It's 100% stock except vacuum gauge, proper size tires, runs great,clean egr ports,new 02,no check engine light. I am a mechanic & have rebuilt many many honda motors including this one.It is timed perfectly,proper compression,valve lash ect. I got 55mpg 3 times.Once i was going about 55 on a long trip feathering gas.The other 2 times was hwy/city mix shutting engine off and coasting alot,also watching vacuum gauge to keep in lean burn.Nnder normal conditions without shutting engine off, city/hwy is averaging about 43mpg

My question is for all vx owners who get more then 55mpg. What am i doing wrong to not get more then 55mpg?

[bestclimb]

welcome,

I'm not a VX driver but have a DX and am knocking on the door of 55mpg with it.
have you read the 100+ hypermiling tips?

City driving I suspect makes it very hard to keep the thing in lean burn. Breaking early and coasting to give the light time to turn green may help in your city driving.

Have you checked your odometer/speedometer against a GPS (distance) or distance of a known route? If not you may already be much closer.

instantaneous fuel consumption readouts are nice MPGuino is not hard to install.

[MetroMPG]

Originally Posted by robertsvx

normal conditions without shutting engine off, city/hwy is averaging about 43mpg

My question is for all vx owners who get more then 55mpg. What am i doing wrong to not get more then 55mpg?

I think you answered your own question there.

43 mpg sounds like what you should expect to see from a car like the VX driven "conservatively" (minus lots of driving without brakes, or engine-off stuff). After all, in mixed use, its ace in the hole - lean burn - isn't contributing much.

Highway driving at moderate speeds in continuous lean burn is where these cars really shine.

[redline5th]

Yeah, you're definitely getting above average mileage. Excellent work! You've got a great light weight chassis to work with.

From there you might work on some aerodynamic mods and weight reduction.

[user removed]

Worst mileage for me recently due to local temps exceeding 100 on many days.

AC kills mileage.

VX is superb at DFCO use it to anticipate any unwanted stops. 5th,4th,3rd downshifts to maintain DFCO when slowing down.

Pulse & glide the AC, in particular whenever you are cruising and especially in DFCO, you want to go max air, recirculate, and max fan. It will raise your DFCO threshold RPM but you can compensate by downshifting to keep engine speed above 1300 RPM.

Accelerate briskly (about the traffic flow rate normally) and get it into lean burn cruise fairly quickly. Do not use AC on acceleration.

In some cases it may be better to just bite the bullet and get on the limited access higher speed roads, if you have to use AC. This strategy minimises the time you are using AC, while slower stop a go situations increase the total AC power consumption.

You live fairly close to me and probably have already experienced the extreme heat this summer. At 90-93 degrees I can tolerate no AC, but when it hits 106 here I either use AC in the car or just ride my motorcycle, which gets close to 90 MPG.

regards
Mech

[user removed]

Forgot some things. VX lean burn threshold is 6 inches of vacuum, if you can't feel lean burn engage.

Without AC lean burn acceleration is practical. Remember to accelerate in lean burn in 3rd gear is about the same fuel consumption as no lean burn in 5th.

The VX has very tall gears, 3rd will get you to about 110 MPH at max revs. A balance of under 2500 RPM operational limit and using 3rd 4th and 5th gears for acceleration may keep you in lean burn more, but dragging out the acceleration phase of operation may not be your best tactic.

My VX is a rebuilt salvage vehicle that I bought in March 2008. It had sat in an insurance training facility (controlled environment) for close to 13 years and had only 27,492 miles on the odometer. It now has 58k miles.

Tires can be a huge factor, with rolling resistance and significant part of any mileage penalty. Run the tires at sidewall max to minimise rolling resistance.

When you are cruising keep engine RPM as low as possible, but above 1000 RPM. Even in 5th at 1k RPM you can still stay in 5th gear. This is where the mileage gets really high, probably close to 70 MPG steady at 35 MPH in 5th with no AC. With AC increase your average engine speed by about 25% while still trying to stay below 2500 RPM.

regards
Mech

[Ryland]

The gasoline you are putting it can also play a role, pure gasoline is the only way to go, no alcohol.

[brucepick]

Originally Posted by Ryland

The gasoline you are putting it can also play a role, pure gasoline is the only way to go, no alcohol.

That's easy for you to say! Here in the Northeast, I can't recall when I last saw an alcohol-free pump. At least I guess we can say we're doing our part to keep the corn belt farmers happy.

[robertsvx]

thank you bestclimb,metro,redline,bruce,ryland & old mechanic for responding with great tips and ideas.Sorry it took a while to get back.For fun, because is has been +90F this past week,i tried something different.with a slightly heavy foot and the A/C on full time, i went 200 miles and only got 33mpg.this proved that we hypermilers have to work for high mpg figures.
few questions for old mechanic-my idle is about 22" vacuum, my lean burn kicks in a 6" and kicks out at 3". Does this sound about right? Have you ever got above 55mpg? looks like my dfco rpm is the same as yours because with a/c off, injectors stay off below 1000rpm,and 1300rpm with a/c on.
I'm glad to hear that my vx is getting the milage it should but i still want to get better then 55mpg.i am little disappointed they rated this car 55mpg from the fctory and have yet to get better then 55. one problem is i carry about 150lb of tools around with me because im a mobile mechanic.Also where i live is in the mountains so its hard if not impossible to stay in lean burn up hills(the car really slows down).

few other things,my speedo is right on,tires are correct 165/70/13 summitomos @45psi,gas is mainly enmark 87octane sometimes i put premium,currently i have no aero mods,oil is 5w30,timing 16 degreesbtc @ 600rpm.

thank you all for resonding.please keep it coming.are there any other tricks for this car in particular? one idea i might add is a hobbs vac switch to turn on and off a/c above so many inches.

lets get more ideas and tips up for the honda civic vx.thanks

[Quasimoto]

Putting premium gas in anything but a high compression engine is just a waste of gas and money. I does absolutely no good, since it needs the higher compression to ignite the higher octane fuel. Stick to regular gas and save your money.