Found a Civic VX; Great Mileage Starts Now! - Page 3 - Fuel Economy, Hypermiling, EcoModding News and Forum

james · 01-14-2009, 06:50 PM

Congrats on the VX. You will love it, though it can be a bit tempermental. Mine is a fed vx with 130 K on it and when I got it it was lowered and the lean burn hardly worked. I was getting about 45 MPG then. It went up to about 53 once I got the lean burn working. I would definately get the lean burn going. Also, do a partial grill block. The grill block added a couple of mpg. The Lrr tires added about 3 MPG (and I just replaced 2). I would definately recommend the sumitomo htrt4 tires in the 165 size. Mine now gets 52 MPG in the snow and ice 15-20 degrees F, with 3 passengers!
Follow the advise of others on the site on putting the right spark plugs in and gap them correctly. also check valve clearance, air filter, cap and rotor. check ground wires. Since yours is over 300k I would check compression. I would guess that yours would have more trouble than mine getting high MPG just because of the milage on it.

For driving tips: With the lean burn it is more important to keep in lean burn than to keep the revs down on the uphills. Lean burn only works in 3, 4 and 5. Shift down to 4 or even 3 to remain in lean burn. On downhills, coast in N when possible. I have found that my car idles lower when I turn the fan off, so I do this when coasting long distances. I use the fuel cut quite a bit, but only when I dont want the momentum, like on steep hills to avoid using the brakes, or when approaching a stop. Otherwise coast in N for FE.

NachtRitter · 01-15-2009, 02:36 AM

Hey James - Thank you very much for the tire recommendation!!

Didn't realize how difficult it was going to be to find 13" LRR tires in the stock size! Also appreciate all your other tips ...

Looking at the progress of my current tank... ~250 miles at half tank... so target is still looking like ~50mpg...

I think what Clev said is correct... I'm thinking that on my very first ever fillup (back on 12/30), the station fuel pump might have shut off early, giving me a higher than expected first tank MPG result and then a lower than expected second tank MPG result (which is actually true... I was surprised how high the result of the first tank was given that the orig owner drove most of that tank and was claiming only 30 to 35mpg)... and now this tank is more in line with "reality".

Phew, I think...

Clev · 01-15-2009, 02:45 AM

Quote:

Originally Posted by NachtRitter

Hey James - Thank you very much for the tire recommendation!!

Didn't realize how difficult it was going to be to find 13" LRR tires in the stock size! Also appreciate all your other tips ...

Looking at the progress of my current tank... ~250 miles at half tank... so target is still looking like ~50mpg...

I think what Clev said is correct... I'm thinking that on my very first ever fillup (back on 12/30), the station fuel pump might have shut off early, giving me a higher than expected first tank MPG result and then a lower than expected second tank MPG result (which is actually true... I was surprised how high the result of the first tank was given that the orig owner drove most of that tank and was claiming only 30 to 35mpg)... and now this tank is more in line with "reality".

Phew, I think...

Yup, those darn gas pumps. My previous 37 mpg tank (a new high) was followed up by a 33 mpg tank, bringing the two-tank average back down to around my winter average.

I could get more accurate results by always going back to the same station and same pump, but paying less per gallon is more important to me (as is getting the most miles out of a tank so I fill up less often.)

james · 01-15-2009, 02:25 PM

Yep,
the vx is notorious for having large variations in the amount of gas you can get into the tank...which, because of its small tank, makes the MPG calculations vary considerably. All you can do is get FE instrumentation, or take the average from several tanks. I typically see differences of 10 mpg or more per tank. If you get one bad one it could be that the one before was much better and the following one will be better. Just take the avg of several tanks.

james · 01-15-2009, 02:48 PM

I'd get that grill block in right away. The white colored waxed veggie boxes from the supermarket are free and waterproof for a while. They burn hot so dont put them inside the engine bay. I just throw them in and put clear packing tape around the edges to keep them in. Not beautiful, but not too bad, and very cost effective. Be careful not to block too much right away. If you are not using the A/C you can block much of that side of the air intake.

My fed VX with the shift light tells me to shift from 2nd to 3rd at 19 mph, 3 to 4 at 26 mph and 4 to 5 at 30mph under really light loads.

NachtRitter · 01-15-2009, 04:06 PM

Hey James - I definitely will do the grill block (as well as other aero mod things) but not 'til I get a decent baseline of pre-aero mod FE. With the fuel fillup variability (as you mentioned and as I've discovered), it'll take a few tankfuls to get a baseline I can be confident with.

After I have a baseline, then I will do instrumentation to further refine my driving style, and after that I will start with the aero mods. I'm doing it this way intentionally because I know I'll be modifying my driving style regardless and didn't want to throw another variable into the overall FE progress. (I'd like to be able to highlight what changes have what FE impact.)

Of course resisting the urge to do simple aero mod stuff is going to be tough... So we'll see how well I can stick to my plan...

Switching to the Fed ECU is yet another variable, but I really do want that to be part of my baseline as well (i.e. pre-aero mods).

Though I don't have the shift light, I have been shifting as low as possible... most often under 2K rpm, and sometimes even under ~1300 rpm... very impressive how well the d15z1 engine can pull at those low rpms!

james · 01-16-2009, 11:23 AM

I sometimes wish I could have done scientific testing for each change to see what mpg improvement I am getting from it. I haven't installed any instrumentation, and I usually do upgrades several at a time so I dont know what effect each change has.
The VX engine is the only gasoline car that has the low rpm torque of a diesel (well, a really small diesel). It will drive down the road fine at 1,100 rpm!

NachtRitter · 01-19-2009, 02:15 AM

On a biz trip at the moment so not much time to write... but wanted to mention that I filled up just before the trip, and on this tank my mileage was ...

... wait for it ...

... 48.9 MPG!!! Woo hoo!!

Definitely more along the lines of what I was hoping for!! Now the goal is to get close to that (or better it!) for the next 2 tanks.

Then instrumentation...

Then aero mods...

Oh ya, received the ECU and the O2 sensor, so need to set some time aside to raid some connectors from another Honda... I promise, I won't raid yours...

james · 01-19-2009, 12:10 PM

Nice work! Keep us updated on your progress.
You are lucky to be in California, we don't hit ecomodding season till april here.

NachtRitter · 01-23-2009, 03:03 AM

Ya, that is true... though it does get "cold" here, I realize it's no where near the low temps much of the northern parts of the country gets...

Currently at 150 miles at the 3/4 full mark... Looks like I should be getting ~50mpg again if I stay consistent.

Kinda exciting (in a weird sort of way

) being able to repeatedly get this kind of FE without either instrumentation or aero mods... I'm really looking forward to the next stage of this experiment!