Realize the full Performance/Economy Potential of a Honda Civic VX

[monroe74]

Originally Posted by *************

I'm going by the old EPA numbers.

That's obviously your choice, but you won't get very far, because they're not realistic.

The old EPA numbers have to be obtainable

They are attainable. They're just not attained very often.

The EPA's estimation for MPG on older cars for their new testing system is definately not perfect, if not flawed.

It turns out that the new EPA numbers for the VX correspond well with real-world results. The old numbers do not.

Here is an example: Official EPA MPG on old sytem for a toyota FJ cruiser is 17/21, they estimated its MPG under the new system as 15/19. However, this is for the 2007 FJ cruiser, a new model, if you look at the 2008 which WAS tested under the new system, its MPG is 16/20.

Every vehicle is different. I'm not intimately familiar with the vehicle you're mentioning, and the numbers you posted are only 1-2 mpg apart. It's hard to draw conclusions from numbers that are so close together. I'm not sure what point you're trying to make by mentioning that vehicle.

I'm not making any general claim about EPA numbers. I'm not saying they are generally reliable. I'm not saying the new system is generally better than the old system. I'm only saying that the new EPA numbers for the VX correspond well with real-world results. The old numbers do not.

So I want to know why people aren't getting the MPG based off of the old EPA numbers, is it because it's truely not obtainable or is it because they just don't care enough to eek out that extra MPG.

As you would expect, the garage shows a wide range of results. Some people care about FE more than others, and are better at getting it. That's why you do indeed see some results that match or exceed the old EPA rating.

Shouldn't the D15Z7 get the same mileage as the D15Z1 if you keep it below 2500rpm and drive it the same?

It would be pretty pointless to install a D15Z7 if it was your intention to drive it the way you suggested.

[GasSavers_topher]

Originally Posted by suspendedhatch

I don't want to use special driving techniques to get the best possible mileage. I don't think that's a realistic figure that you can compare to other cars. Some of those techniques are dangerous or just annoying. I want to get the best possible mileage w/out "cheating". By driving like a normal person and close to the way they drive when the determine the mpg to put on the window sticker.

FE alone is not my goal. When FE is your goal, that also means that saving money is your goal. So almost no modifications are justified because they take too long to pay off. Well to me that's just boring. Having a gutless car is also boring. Having an impressive mpg figure is cool, but not when people can dismiss your car as being gutless or looking like Flight Of The Navigator. I'm not dissing anyone. I'm just stating my personal interests.

Thats exactly how I feel. EXACTLY

[imzjustplayin]

You use it when you need it. Just because I have a 130HP engine, it doesn't mean that I don't want to get good fuel economy all other times. Also if you're saying that the fuel economy numbers are correct for the VX due to the new EPA numbers, can the same be said for the HX? Because if that's true, then it would make the HX no better than an accord or a nissan 240sx.

[monroe74]

Originally Posted by *************

then it would make the HX no better than an accord or a nissan 240sx.

'96 HX. EPA ratings under the new system: 33/41/36.
'96 Accord, stick. EPA ratings under the new system: 22/29/25.
'96 240sx, stick. EPA ratings under the new system: 19/26/22.

So you're absolutely right, assuming you consider 36 mpg (combined) "no better than" 25 or 22.

[thisisntjared]

Originally Posted by monroe74

'96 HX. EPA ratings under the new system: 33/41/36.
'96 Accord, stick. EPA ratings under the new system: 22/29/25.
'96 240sx, stick. EPA ratings under the new system: 19/26/22.

So you're absolutely right, assuming you consider 36 mpg (combined) "no better than" 25 or 22.

dude hez just playin

[imzjustplayin]

Originally Posted by monroe74

'96 HX. EPA ratings under the new system: 33/41/36.
'96 Accord, stick. EPA ratings under the new system: 22/29/25.
'96 240sx, stick. EPA ratings under the new system: 19/26/22.

So you're absolutely right, assuming you consider 36 mpg (combined) "no better than" 25 or 22.

The thing is, the 240SX and the accord CAN achieve the old EPA rating with out a doubt. I don't know how you drive but I do and others I've read or know have achieved the old EPA ratings for MPG. The question is, can the same be said for the HX and the VX or not. I have no idea if you're one of those who mash the pedal or push on the gas despite there being a redlight up ahead or those who drive conservatively but at the same time aren't extreme like a hypermiler.

I just want to know that if I were to drive conservatively but not extreme like a hypermiler, would I achieve the EPA ratings for both of these cars or not. Because if I have to be a "hypermiler" just to achieve the old EPA ratings, then I'll be annoyed. I want hypermiling to be a thing you do that improves your MPG PAST EPA rating, not TO the old EPA rating. Has anyone driven 55mph in either of these cars and figured out what their MPG was?

[DRW]

Here's a list of members on this forum who get better than epa. www.gassavers.org/garage/viewall/epa
It's not hard to get more mpg than the epa rating, you don't have to use extreme methods either.

[suspendedhatch]

************* why don't you go ahead and start your own thread since your questions have nothing to do with mine.

[fibonacci618]

hello and congrats on your hard work and perseverance! i have had a similar obsession with the tripple stage vtec myself ever since i read about it a couple years ago at this site: http://asia.vtec.net/article/d15b/

i noticed you put the vtec-e disengagement at 2500 rpm to keep with where the d15z1 is set. however, according to that article the d15z7 disengages at 3000 rpm. i thought that seemed about right being that that engine is mated to the tranny that has the same gear ratios as EX/Si (and yours) and thus needs a little more rpm to rev. have you tried setting it to 3000 instead? maybe then you could shift right at that point and see increased city driving as well as try to cruise right below 3000 rpm during interstate driving.

a little about myself. i did own a 92 VX but sold it months ago as it had this musty odor when i bought it and i am sensitive to mold, thus i am very picky about owning older cars and cannot handle any car that has been rained and molded. too bad b/c i liked it a lot and its lightness prevailed and even handled very well for a totally stock car with 13" Michelin's.

as a side note, in talking about getting old cars so we can save money and get better gas mileage than newer ones, i think it is worth mentioning i did find out where the water leaks in the back of the EG hatches come from: the window struts getting old and putting more stress on the nut that secures it to the window.

you can get new ones at Advance i think and get nuts from your dealership and have a leak proof hatch once again. too bad no mechanics or honda-tech guys ever told me why they leak but i finally found out b/c i HAD to replace the stripped out nut that broke on that VX soon after i bought it and then low and behold the water puddles ceased.

anyway, i talked to one guy who delivered pizzas and used to have a VX and he missed it greatly, especially as he delivered in his turbo WRX! he said he did get close to the 55 mpg. he also took a power steering wrack from an Integra and gave it ps. i thought if i was ever gonna convert a VX, then a Type R wrack would be awesome since it has the quickest steering ratio--nice wrack!

ok, so i got as low as 39 mpg around town but usually got 42 mpg. my record, on interstate where i kept it right below the vtec diseingagement of 2500 rpm (close to 75 mph), was 45 mpg. i never knew why i couldn't get better than that and if i needed a new O2 sensor or not.

but that brings me to a good question. does the d15z7 use 1 or 2 "LAF" (lean air fuel) sensors? and if they need replaced, what kind is it? is/are it/they identical to VX LAF sensors? if not, is there a supplier that can fetch it from Japan w/o raping us? you gotta understand that i have not known a single person to get this engine and it is hard to find info on it even in the forums. you not only getting one but putting it into an obd1 car makes you a true pioneer and with tuning and all, i have great respect for you.

i had this same idea too but i thought if i get the motor i'd first test it by putting it into an obd2 car, for which it was designed. yes, the 96+ sedans are gonna be 250 lbs or more than a VX, but that's life. after i saw my 93 Si B16 hatch get stolen, i got kinda demoralized about the whole EG h/b thing, despite my former love for them. they just attract too much attention!

so i bought a boring sleeper set: a 95 LX sedan and a 98 DX sedan. the 98 DX is totally stock and i have been getting 36 mpg for the last several fill ups now that warm weather is here and even 37 the last time!

i noticed you have a 37.83 mpg sticker posted. is this about to be updated with a higher #? i may be totally wrong about this but i thought i read that the wide band 02 sensor is more tuned into the lean burn operation, and thus when one is operating their VX above the vtec-e range, they may actually get worse FE in that higher rpm range than a standard non vtec-e d15 (using the same VX tranny) that would still be optimized above the 2500 rpm zone, using a normal 02 sensor. i'd like to see what you got just maintaining a cruise right under 2500 rpms (unless you do move the vtec-e disengagement up to 3000 rpm and keep your cruise below that).

last question i have for you is for the rest of us who aren't brave enough or willing to put your d15z7 into an obd1 car: do you think it is any more difficult to put the d15z7 into a 96-98 Civic DX/LX {requiring the use of the JDM CPU (from a VTi or whatever it comes out of) and running wires for knock sensor and vtec} than it is to put a d15z1 into a civic EG that was non vtec?
thanks

[suspendedhatch]

If you have a musty odor (or even if you don't) you should open up the heater box behind the glove box and vacuum out the leaves and crap that accumulates inside. You should also pull up the carpet and check the mat for mold or moisture. 15 year old carpet should be replaced anyway. Whenever I buy a car, I remove all the seats and most if not all the paneling besides the dash, headliner, and pillars. You will be amazed by all the bobby pins, french fries, coins, expired credit cards, dirt, and melted candy you will find. The sides of the front seats, the center console, and the rear seat cushion are especially disgusting. I also remove the bumper covers and pressure wash underneath them and underneath the car and in the wheel wells. Then steam clean the engine bay.

The JDM D15Z7 uses a standard one-wire O2 sensor.

Although I have it set for 2500 RPM engagement, there are other parameters that also have to be met. Load has to be above 55kPa and TPS % has to be above 30. So it goes that I often hit 4000 RPM but never go into 16 valve mode. In fact, I rarely get out of VTEC-E in my daily commute unless I'm doing it on purpose.

I don't believe any stated RPM engagement point unless it's an official Honda publication. Even when an owner of a Civic VTi says it's at a certain RPM point, this is incorrect because the factory tachometer is inaccurate and also because there are multiple parameters used to determine it. That's why the RPM point will vary with throttle input. When I have time, I'll tune my engagement point on a dyno.

You should never run VTEC-E based solely on a single RPM crossover point. Hysterisis is required to prevent the VTEC-E solenoid from rapidly engaging and disengaging when you're hovering near the RPM crossover. At the very least, you need a "VTEC-E ON RPM" a couple hundred RPM higher than the "VTEC-E OFF RPM".

I work 3 miles away from home so there are long gaps between fill ups in the garage (which I only started just recently). I'm totally satisfied with 38 mpg mixed driving and I have not made any effort to improve upon it. I regularly rev the engine to rev line and WOT shift. Much of what I do with the car wastes gas and so the mpg reflected is lower than this vehicle's potential.

If you have an EG and you don't have some security on it, you're on borrowed time. You're a temporary owner just keeping it maintained so that someone can come take it from you. If you have a problem with that you do what's on Cause For Alarm. http://causeforalarm.thecarthing.com...6/version6.EG/

DEI GPS tracking devices have come down in price. By the end of the year I'll update my website with a Viper 210C install and the alarm will be swapped out for a Viper 5701 for manual trans remote start (vs adding a module to my current 5900). And I'm going to remove it from behind the cluster.

Someone tried to steal my car and actually got the hood open only a week after I moved in to this neighborhood. Other Hondas/Acuras have been broken into on this street. I plan on using my car as a bait car to catch them.

What you are saying about the O2 sensor is incorrect. It is just as accurate rich as it is lean. O2 sensors are not "tuned". O2 sensors are a feedback device. The calibration is in the ECU. Once the ECU is tuned, you can throw your O2 sensor away. They are only useful to monitor the engine in case something goes wrong, or to allow the ECU to make small alterations to the injector duration to make up for real-world variables such as engine wear and deterioration of sensors and wiring. If I disable my AEM wideband O2 sensor I get the same gas mileage.

It would be MUCH easier to put a D15Z7 into an OBD2 car than into an OBD1. Running a couple of wires for the VTEC-E solenoid etc is no concern for me. I don't know what is so difficult about wiring that it intimidates people. With the right tools, the right supplies, and a little bit of practice, wiring is the easiest thing you will do in an engine swap. And yes, you absolutely need the P2J ECU. Although a D16Y5 ECU could conceivably work if you didn't mind not using the 3rd VTEC Stage.

I've never had a water leak in this hatch or my previous hatch.