93 Civic VX -only 38 MPG HWY- Do I needd steriods for 50+ MPG?
 

I think I posted this in the wrong location the first time.

I just got a little red VX. 320k miles. The 2nd owner said it was getting 45mpg. He lied- I'm only getting 38!

Tune up: I've changed the plugs (NGK,) wires, cap, rotor, manual tranny fluid (honda grade stuff), air and fuel filter. Seafoam in the intake manifold. Filled the tires with air to 32psi (they were at 12-15psi) Car went from 36mpg HWY to 38MPG-!!??

Cleaned the IACV and TB: https://www.honda-tech.com/showthread.php?t=1575913
Now I'm having idle problems.
-On start up it goes to 1500 rpms then after 2-5 minutes it goes to 1000rpms.
-Once warm 650.

Brakes:
If I'm at a dead stop with the brakes depressed hard and I release the pedal my rpms go up. I've done a break test and everything seems fine.


Compression test:
Cylinder 1- 189
Cylinder 2- 190
Cylinder 3- 191
Cylinder 4- 193
-That's good right?

I haven't checked the timing yet:
I want to get this done, and get the valves adjusted.


Transmission:
-2500ish rpms @ 73-75 MPH 5th gear
-2000ish rpms @ 60-62 MPH 5th gear.

QUESTIONS:
How do I know when the engine goes into lean burn mode and what does it feel like?

Lean Burn?:
-When I'm driving at about 65 miles per hour it feels like I'm getting a sudden boost of power, but it doesn't really go anywhere. Smooths out a little, but it's almost like a loss of power. I know that's contradictory sounding.

I might be imagining things but, on my drive home I disconnected the O2 sensor. (hoping that the rpms wouldn't go to 1500 when I started it, but they still did) However on the drive home it seemed to have lower slightly lower RPMs in high gear and I didn't get that strange surge thing that I mentioned just above. (lean burn mode?)
Check engine did come on, and shifter light went away.


Thanks for reading this and I appreciate your feed back!

By the way, 320k miles and it still has the original clutch I paid $1150 for it. Has a little rust. Did I get hosed on the price? It's all original a far as I can tell.

Re: 93 Civic VX -only 38 MPG HWY- Do I needd steriods for 50+ MPG?
 

THAT DEPENDS HOW LONG YOU OWN IT - IF THE ENGINE BLOWS UP NEXT WEEK - BAD DEAL. IF YOU DRIVE IT FOR FIVE YEARS - EXCELLENT DEAL

Re: 93 Civic VX -only 38 MPG HWY- Do I needd steriods for 50+ MPG?
 

15% difference in MPG with a new driver and a new route? That is not unexpected. If he said it got 45mpg and you got 20mpg then I'd think something was weird.

Now, that said...a lot of people do way better than 38mpg with a VX.

Re: 93 Civic VX -only 38 MPG HWY- Do I needd steriods for 50+ MPG?
 

I have had six manual-transmission Hondas, including two '95s, and my '95 VX took me the longest to get the best mileage out of it. Shift sooner than you want to, using the shift indicator light. Keep the tires inflated to 40+ (the stock springs and shocks are soft enough that the ride will still be OK). Don't make short trips; consolidate errands so that you don't waste fuel by warming up and cooling down time and time again. Whenever the engine and catalyst are cold, it will not go into lean burn. If your car is lacking, a valve lash adjustment, clean spark plugs, good plug wires, and a functional wide-band O2 sensor will make a world of difference.

My VX was getting 60+ mpg regularly, and I got as high as 77 mpg with no body mods. Some folks on the site have had good luck with grille blocks and lightening their cars (by pulling out the A/C, etc.). I never got around to it.

I wish you luck with your high-mileage VX. I sold mine to my uncle with 234,000 on it, and it's still going strong. If yours is half the car mine was, you'll love it.

Re: 93 Civic VX -only 38 MPG HWY- Do I needd steriods for 50+ MPG?
 

Wait, so it's normal for the VX to have the RPMs at 1500 for the first few minutes? It takes about 10 minutes to reach 650rpms. I thought that the IACV was going bad. That's what a lot of other people told me.

If I pump the brakes the rpms surge. (Dead stop, push two or 3 times and the rpms will go up about 400-500 rpms. If that's normal that I'm not worried. However if its a safety issue then I'd want to get it fixed.

The rpms also go up and down if I'm in neutral coasting. Up and down from 700-1200. I've checked for vacuum leaks but I can't find any.

Last but not least the rear wheel is bent and causes a lot of wobble. I'd think this would hurt the mileage. Does anyone have a spare silver VX rim?

As for tires. I've got 4 different ones. Each wheel is a different make/model.
I want to get a new rim and 4 new tires.
Any suggestions for tires? It's going to snow here soon and the winters in MN are pretty bad.

Thanks!

Re: 93 Civic VX -only 38 MPG HWY- Do I needd steriods for 50+ MPG?
 

Winter in Minnesota, eh? Got to be worse than lower Michigan. I just bought used winter tires on steel wheels. I hope my winter driving becomes easier with them because I HATE driving my VX in the snow with all season (really three season) tires. I have had several sets of all season tires and none were any better than the others. So you should consider two sets of wheels. You can get by without winter tires - 14 winters without them in my case. I'll let everyone know how much better my VX handles with them. I really don't care what the mpg will be from mid December to early March.

Re: 93 Civic VX -only 38 MPG HWY- Do I needd steriods for 50+ MPG?
 

So did you get 4 tires? Or can you get away with just 2 in the front? If so, do I need to get 14in or 13in front tires? What did you get and how much was it?

Re: 93 Civic VX -only 38 MPG HWY- Do I needd steriods for 50+ MPG?
 

I had Michelin Destiny tires (175/70R13) on the VX rims. My VX was unstoppable in the winter. Last winter, I was able to push snow with the front bumper, and never had any issues.

The Destiny tires have large tread blocks on the edges of the tread, and they are not connected by a thin strip of rubber, which a lot of tires have to reduce noise. By not having that strip, they are MUCH better in the snow than most all-season tires.

Granted, I do not have Michigan-quality winters here in Indy, but I've driven with 4"-5" on the major roads and up to 7" on side streets, with no traction problems.

After being on the car for 40,000 miles, the tires were less than 1/3 worn (and I am not easy on the tires). They technically are not Low Rolling Resistance, but I consistently got mileage in the high 50s and low 60s with those tires on the car.

I would recommend those tires to anyone with a VX.

Re: 93 Civic VX -only 38 MPG HWY- Do I needd steriods for 50+ MPG?
 

I have been told that you should use winter tires on all four wheels. In addition to handling snowy roads better, the tire compound is softer so will be more flexible than standard tires when it's really cold out - like Minnesota.

I bought four 14 inch wheels/tires. Two are Yokohama K2 720 and the other two are Firestone Winterforce. They are 185 65R14 so they are considerably wider than the two sets of 175 70R13 I currently own. I would say they have about 60% of tread life remaining. I paid $125 for all four.

I have three sets of wheels with tires and another set of alloy wheels without tires. I bought my current VX with the OEM Enkei's but have bought the other sets of wheels for $125 per set or less. In case I'm unclear, that's 12 tires and 16 wheels for one car LOL!

Re: 93 Civic VX -only 38 MPG HWY- Do I needd steriods for 50+ MPG?
 

The problem with using winter tires on the front and non-winter tires on the back is that the combination of good traction in the front with poor traction on the back makes for squirrely handling and a loose rear end as the back comes unglued well before the front comes close to losing control. You want 4 tires that have about the same traction and handling characteristics unless you like doing uncontrolled 180's and 360's on snow or ice.

The easiest way to handle snow tires is to keep a set of 4 wheels with snow tires and another set of 4 wheels with summer tires and then just swap them out seasonally. Both sets of tires last longer than normal since you are only driving on each set for part of the year, so your main added cost is for the extra set of wheels. You can get steel "take-offs" wheels fairly cheaply from performance tire shops as these are the OEM wheels that people trade in when they get a set of fancy alloy wheels. The 13" and 14" OEM wheels for 5th and 6th gen Civics will fit the VX. I got a set of 14" wheels and mounted Insight-I Bridgestone Potenzas on them for my car and mounted some Hakkapelitta winter tires on my stock set of 13" wheels.

Re: 93 Civic VX -only 38 MPG HWY- Do I needd steriods for 50+ MPG?
 

Stock size tires (or at least same overall outside diameter) is important. If they aren't the right size, your MPG estimates will be off potentially dramatically.

Why are you coasting in neutral?
The VX has DFCO that is immediate. The engine is effectively off so long as you are warmed up, in gear, above 1100 rpms, and everything in the car is working correctly. The injectors actually shut off entirely. It pays to downshift and keep it in gear when decelerating.

Erratic idle could still be issues with the IAC, so you could try cleaning it again. My volvo wagon needed to be cleaned and re-cleaned 3 or 4 times before it worked well enough.
The vx will waste more fuel idling in neutral when coasting than if you downshift. The rpms should be above 1000 if you are traveling above any speed but a crawl. This way when you put it in gear your revs are closer to where they will need to be. When you slow to a stop the rpms drop.

Dropping rpms when braking is common. That's a small motor. Any load will cause slight idle changes. Even a brand new IAC and new sensor still wont make it totally stable. Newer technology in newer cars makes their idle more stable than your VX will ever be. Your braking puts a load on the booster as well as your altenator for the brake lights. Both affect idle.

If the car will idle at 650 once warm without loping up and down, you're good to go.

Driving technique is what comes to mind here. Sure, matching tires is what you need. Low rolling resistance will help. A lot of little things will help. Your baseline suggests that driving technique may be your culprit. Accelerating to stoplights/signs is a bad one. There's a lot of helpful info on this site about driving for MPG's.
Weight could be a factor. Are you hauling lots of passengers or ballast?

Learn to feel the change from lean burn to not lean burn. It's at about 1/4 throttle. Shift when the up indicator says so. Sometimes climbing hills it isn't practical, but on a flat plane it should be no problem.

NGK plugs that are listed on the timing belt cover? Those are important.
B

Re: 93 Civic VX -only 38 MPG HWY- Do I needd steriods for 50+ MPG?
 

benfrogg, DFCO is great if you intend to decelerate but neutral coasting is a more effective strategy for certain situations. The situations are generally cruising on level or slightly descending road where you intend to keep approimately the same speed.

Re: 93 Civic VX -only 38 MPG HWY- Do I needd steriods for 50+ MPG?
 

True, coasting in neutral is handy for certain situations. I tried coasting in neutral all the time and not downshifting and lost MPG's. I assumed 1sthonda had been doing the same. I realize that coasting in certain situations is better than decelerating.
Anyway, all good info.
B

Re: 93 Civic VX -only 38 MPG HWY- Do I needd steriods for 50+ MPG?
 

Wow, this is all great to hear. Thank you so much. I started driving differently. a few days ago. I can tell when lean burn kicks in. I shift when the light tells me, even when it doesn't make sense. 25-35 mpg and in 5th gear, while slowing accelerating didn't make sense at first, but the light tells me it's okay so I guess so right?

I still want to get the timing checked. I think that will make a big difference. I guess I could try cleaning the IACV again. It would be for a 3rd time. (it's really clean looking. The plastic inside it bright white.) I was going to buy another one for a junk yard, but I haven't gotten around to it yet. Is there anyway to tune the IACV? I noticed a little allen screw. Looks like a 4.5mm.

Someone also told me that there's a chance that my RPMS being high at start up was because of a bad coolant sensor. Is this possible?

Also, I have a bad rim on the rear passenger side. It makes the car shake a little. I figured that was causing it to lose MPG.
-Any ideas?

Re: 93 Civic VX -only 38 MPG HWY- Do I needd steriods for 50+ MPG?
 

Shifting at low RPM and making use of the VX's relatively plentiful torque by opening the throttle is probably effective for some or all of the following reasons:
- Reduces energy spent sucking air through a closed throttle
- Reduces reciprocation loss (don't forget that the pistons change direction twice per revolution)
- Reduces engine friction, which reportedly rises exponentially with RPM
- ...and whatever else I forgot.

I get my similarly torquey 2008 Volkswagen into 5th at 1000-1200RPM, 25-30mph, and get very good results. Its fuel economy over 35mph is held back by the lack of 6th through 10th gear...

It is common, after discussing fuel economy on internet forums, to think that RPM isn't as important to fuel economy as you'd assume, and to think that the "gas pedal" is what matters...but it's by far the opposite. The "gas pedal" doesn't cause the engine to dump in more fuel than it needs; it just removes an air restriction. Misguided people spend lots of money on less restrictive intakes hoping that they can then restrict it more at the throttle.

Re: 93 Civic VX -only 38 MPG HWY- Do I needd steriods for 50+ MPG?
 

I agree with theholycow. Low revs and wide open throttle plate for climbing hills instead of downshifting to 3rd and running less than half open. All good points.
I must say, my vx is sluggish at best during this kind of driving. Sometimes I'll get up to 60mph (in a 50 or 55 zone) to try and keep the car in 5th gear all the way up. I also make an attempt around town to accelerate slowly and keep lean burn in all gears once the car is warmed up. I make it to the speed limit, just not as fast as everyone else. This is sometimes not safe but most of our major roads are two lane roads. People can easily pass if they dont like my speed.
The timing on my car was way off when I got it. It was like 1 degree above TDC. Who knows for how long or why. If you DIY, get a budy who knows how to do it. The timing marks are tricky to see on the casing; you line up two marks in the plastic (like aiming a gun) to the spinning harmonic balancer. I marked with a paint marker the grooves on the harmonic balancer before hand.
I went to the most advanced side of factory specs, which is printed on a label under the hood. I can't remember what that number is right now.
This also changed idle speed, which I had to then adjust via the flat head screw on the throttle plate. The more advanced the timing, the faster the idle.
High rpms on start up is to get that engine warm and prevent stalls when cold. It is possible that the coolant sensor could cause problems, but its more likely to cause problems once the car is warmed up. This would cause a CEL and cause the ECU to go into open loop mode which would also likely diminish your fuel economy a lot.
That rim cant help. I don't know about FE, but driving comfort and safety are needed too.

Here's link to my similar quibble. I had the same problem you do when I first got the car. This may shed some light.
https://www.gassavers.org/showthread....ht=vx+horrible

Re: 93 Civic VX -only 38 MPG HWY- Do I needd steriods for 50+ MPG?
 

I have some Kumho Power Star 758 on them 175/70/R13. What's the best tire for gas mileage with this car?

Re: 93 Civic VX -only 38 MPG HWY- Do I needd steriods for 50+ MPG?
 

When you guys mentioned tuneup, you forgot the replacement of the PCV valve and the valve lash adjustment.. Also I recommend cleaning the throttle body thoroughly since it'll likely be covered in gunk in all the little passages and under the idle screw. Last thing I can think of is to redo all of your electrical grounds, check the ohms value of them from the ground point to battery ground, getting them to near zero ohms, and replacing your vacuum hoses because by now they're probably rotten and need replacing.