Two 1998 Civics - inexpensive improvements?

[MamaBear2015]

Originally Posted by Ecky

VTEC is essentially having two cam profiles optimized for different rev ranges, and usually the switchover is 4-5,000RPM. It wouldn't surprise me if most VTEC engines had better fuel economy (all else being equal) than their non-VTEC counterparts due to the lower-rev-range cam profile being tuned for lower revs, rather than aiming for the middle as is the case with a lot of Honda's non-VTEC designs.

As firehawk618 said, most VTEC engines (aside from the ones in the VX/HX models) are geared much shorter though, which probably accounts for most of the mileage differences.

I read a thread somewhere, saying that the best thing you can do for your MPG is to keep the RPM below 3000, and better yet below 2000, the latter of which aint so easy. But I can pretty easily stay below 3000, except in rare cases when I have 100 feet to accelerate onto a 65 MPH highway, or face a concrete barrier with no pullover lane. ( Yes, we have one like that near here - thanks Denver! )

Where did that little chart you posted come from?! That would be phenomenal!

[MamaBear2015]

Well now this is a mystery to me. I just went out and looked at the engine plates in front ( thanks for the locations ). The Teal car that we got first, is a Y7. The Silver car has a filthy engine and I had to use a napkin to TRY to wipe it clean enough to read, but THAT ALSO appears to be a Y7. BOTH are 1998 Civics. So WHY would the Silver car be SO much more assertive and smooth than the Teal car? Remember, the Teal had 94,500 miles when we got it in January and the dealer said they got it from the first owner. The Silver car was bought from the second(?) owner and was the one with the opaque blackened air filter and plugs that were nearly down to the insulators, and even then, before I changed them, it was more assertive and smooth than the Teal. Now I'm really curious.

Would photos of the engine compartments help?

By the way, a local car wash says they can wash the engine for $20 extra but don't guarantee not harming sensors ( they have people sign a waiver ). Is it very risky to sensors or are they just doing CYA?

[MamaBear2015]

I just took a look in the glove box and found the original window tag.

[Ecky]

Which chart, the one in my signature with my MPG stats?

I personally wash my engine bay now and then. If you're going to do it, it's probably a good idea to put a plastic bag over your alternator and air intake, but so long as you don't take a very high power pressure washer to it, washing should be alright.

I can think of a few other possibilities on why Teal might not have as much power. Dirty injectors, clogged EGR or PCV valve, not sure D series engines had EGR valves? Possibly some crud buildup in the intake manifold. Does it burn any oil?

[MamaBear2015]

Originally Posted by Ecky

Which chart, the one in my signature with my MPG stats?

Yeah.

I personally wash my engine bay now and then. If you're going to do it, it's probably a good idea to put a plastic bag over your alternator and air intake, but so long as you don't take a very high power pressure washer to it, washing should be alright.

Ahh.

I can think of a few other possibilities on why Teal might not have as much power. Dirty injectors, clogged EGR or PCV valve, not sure D series engines had EGR valves? Possibly some crud buildup in the intake manifold. Does it burn any oil?

Not really. I checked it after the first 3000 miles and it was down about 1/4 quart.

As far as injectors, I have some BG44K here, but the Toyota Nation people used to say that it wasn't recommended by the manufacturer, so not to use it..

Use it?

I think PCV valves are a 5 minute job. Not sure about EGR's.

[Ecky]

To make a signature like mine, follow the instructions here:

http://ecomodder.com/forum/showthrea...ure-20941.html

You'll also need a fuel log, which you can create for your car(s) in the "Garage" section linked at the top of the page (next to Store, Wiki, Home).

~

After some google'ing I'm still not able to tell for certain if your car has an EGR valve or not. Does it run rough at all? I'd probably replace the EGR for good measure anyway since it's so cheap.

I'm pretty sure the 98 still had a mechanical distributor. You might visually inspect both to see if the spark advance is roughly the same. Retarded timing could cause lack of power too.

Anyhow, I recommend starting a fuel log and reading the tips here:

100+ Hypermiling / ecodriving tips & tactics for better mpg - EcoModder.com

Perhaps someone else will come along with some more ideas related to your lack of power.

[MamaBear2015]

Originally Posted by Ecky

To make a signature like mine, follow the instructions here:

http://ecomodder.com/forum/showthrea...ure-20941.html

You'll also need a fuel log, which you can create for your car(s) in the "Garage" section linked at the top of the page (next to Store, Wiki, Home).

Thanks, but I just meant that it was impressive. I wouldn't get into it unless I could do as well.

After some google'ing I'm still not able to tell for certain if your car has an EGR valve or not. Does it run rough at all?

Maybe a teensy bit, at random? No, it's just not as assertive and smooth ( for lack of better terms ) as the one we just got last week. That was why I thought, at first, that the Silver one we just got, might have been a Vtec. The difference is significant enough to really notice. Same year and apparently same engine.

I'd probably replace the EGR for good measure anyway since it's so cheap.

Easy to do?

I was just looking up the PCV, which has been easy in previous cars over the years, but it seems they made it hard in these cars.

I'm pretty sure the 98 still had a mechanical distributor.

Yup. I replaced distributor cap & rotor ( and plug wires ) in the Teal one already. Made no real difference.

You might visually inspect both to see if the spark advance is roughly the same. Retarded timing could cause lack of power too.

Not sure what you mean. I'm not a mechanic or auto tech, so I don't have equipment or much knowledge of this.

[Ecky]

Sorry, meant PCV valve.

When you mounted the distributor, you probably noticed that there was some "play" in the bolt holes. That is, it can be turned a bit clockwise and counterclockwise. Turning it more counterclockwise (toward the firewall) advances ignition timing. Turning it more clockwise (toward the front of the car) will retard the timing.

Advancing ignition timing generally results in increased power and economy (and moves the torque curve, I believe?), but going too far advanced can cause detonation. It's generally advised to use a timing light when replacing a distributor to get it back to factor specs, but you could probably just eyeball it and make sure it's really close to the same position as on the other car.



^ In this image I've circled one of the bolts. If you compare the two very closely there, you'll be able to see if Teal's is advanced or retarded relative to the other one. This isn't the "right" way to adjust timing, but it'll do in a pinch.

[MamaBear2015]

I didn't mount the distributor, just changed the cap and rotor.

[firehawk618]

Originally Posted by MamaBear2015

Thanks. That IS interesting. I'm thinking of mounting it right on the dash, and it would need double sided tape, I suppose.

The absolute best device for trying to optimize MPG is the MPGuino though. It's a 4 wire hook up, not plug and play.

Constant 12v+, ground, one injector and one speed sensor.

If this interests you I can send you a link to the pre assembled one I purchased online. The only real down side is you must make your own enclosure for it.

Once installed there will be a couple tanks of dialing it in to be accurate for your car but even when it's not totally dialed in the refresh rate and sensitivity of it cannot be beat by the Scangauge or Ultragauge.

The SG and UG are fairly slow on our cars due to the communication protocol our cars use unfortunately. Don't get me wrong, either one is better than nothing by a long shot.


Here's some youtube videos of them in action.

https://www.youtube.com/results?search_query=mpguino