92 VX Seeking 50+ MPG
 

Hey guys and leety in California. I am "manning up" and starting my own thread.

I love my 92 VX. I Know I don't know it's real history, but it is all original, in great shape other than the paint on the roof and the hood: Tahitian Green Pearl (hence her name "Pearl"and I've never named a car)
Found it on eBay and bought it sight unseen. 255,000+ miles, bad paint and all. ($2,500 if you're curious).

Flew to One of the "villes" in North Carolina (Outside Asheville).
Put on new tires and drove it 1,500 miles back to elevation 5280, Denver CO!
Despite the conditions (wind, 18 wheelers, hills and mph 65-75), I got mpgs from 44-48. I was on the road all day long in the late August heat wave (w/little to no a/c!

Since then I've had immediately necessary maintenance done:
Major tune up (ran like a whole different car)
Fuel filter
Valve cover and gasket
Thermostat
Three oil changes including a couple of BG's products to clean the dirty engine
Two radiator flushes (not standard Honda stuff in there)
Cleaned injectors
Plus some minor brake work, replaced an axle.
The best mpg I've gotten is 48.6.
The "worst", 37.17.
I am using Road Trip (app) and have confirmed my odometer and trip meter against a mile marker. Yay they match! Boo odometer is right!!

The thing is that there is often up to ten mile variation per fill up is interspersed--a couple of 47 mpg results then a 37 and a 40 show up. Some known variables allowed for the low numbers, side wind at highway speed, cold weather...when they stayed low for three readings, we discovered a inoperative thermostat.

Now that I've replaced the broken thermostat and had the injectors well cleaned, I can't wait to see the results. I also set the tire pressure to the manual suggestion. Of course, since my commute is only 14 miles a day, it will take a while to reach half a tank so I can refuel! (Bummer :-)

Tires also make a massive difference in MPG. Going from my old set to my RE92's I saw a minimum of 7mpg boost. RR makes a huge difference apperantly.

I'll add those to my wish list. They seem to be $ and hard to find for my car. Advice on that? (Thank you)

*I had Falken Sincera 828 175/70-13 installed before I left Asheville.
They were a great price, but I wasn't thinking RR at the time. Maybe. I made a lucky choice?
I have Defenders on my 97 HX (which surprised me w 54.6 highway over 160 miles.)

My MPG took a big dip right after I got my HCH back from an alignment; I found out (over halfway through the tank) that the shop had politely set my tire pressure back to the manual's recommendation: 30psi! And one side was actually more like 28.

When I got the car the tires weren't new, and I immediately pumped them up to about 45psi all around. Mileage took a big jump, and I got another 20,000 miles out of them. If higher pressure adversely affects tread life, I haven't seen it yet. Do note, however, that it will affect your tires' grip.

Try this for more consistent tank fills. Left rear tire on top of the 2X4 will raise that corner of the car and get the air pocket out of the tank. Two clicks on medium speed of the pump with a few seconds of wait between them.

regards
mech

http://ecomodder.com/forum/attachmen...3&d=1418049897

This was posted with the main point left out.
I stopped at a tire store to raise my front tire pressure. I decided to double check what they had done and one tire was set to 45 the other 38. Some favor...�� ...
My tire sidewall says 51 max psi. What is best?

Do I remove the gas cap when on the 2x4? Is there a wait for air to move?
Then I drive to the gas station. Do I remove the nozzle?
Could an air pocket explain overspills at the pump?
Thank you very much. :-)
Michelle in Denver

I drop the 2x4 out in front of the tire, before I get out to refill. Gas cap off after I get out. I like to run the pump on low speed (first click) until it shuts off automatically, then wait a few seconds and top it off.

If you are spilling fuel, then you might just listen to the gas level rising in the filler neck and shut it off when it gets to the top. I don't think I have spilled any gas in a very long time at a gas station, years at the least, maybe a decade.

You don't want to fill it to the top of the filler neck, about 4 inches below keeps the evaporative emissions system from being flooded with liquid fuel which will destroy the charcoal cannisters contents. You can probably see the small vent hole in the top of the filler neck very close to the restrictor for unleaded fuel.

Always fill when you have somewhere to go that will use enough fuel so the chance of the fuel expanding into the evap emissions circuit is eliminated.

An example would be filling and immediately parking on hot asphalt in summertime. The fuel in the tank is typically around 60 degrees fresh out of the pump. Heat that to 90-100+ degrees and it will expand and flood the evap emissions vapor line. Repeated events like this could ruin the charcoal cannister that is supposed to hold excessvapor pressure in suspension, to be purged the next time the engine is started.

regards
mech

http://www.aa1car.com/library/evap_system.htm

My 94 federal vx came with the original tires in 2008. The car had been totalled and sat in an insurance training center for 14 years (controlled environment). It had 27,492 miles when I got it with the rear end shoved into the trunk.

The original bridgestone tires were rated for 38 PSI. I ran them at 38 at 14years age until I replaced them after I got the car repaired and painted. Lost 7MPG average with the Michelin X tires I installed!

Best road trip on the original tires at 64 MPH on the Interstate was 300 miles on 4.627 gallons of fuel on the original tires.

regards
mech

Thanks folks. I drove 232 miles (100 mi with my cleaned fuel injectors) and my replaced thermostat. My mpg actually went down to 37.
I refueled today, topped of the tank while positioned on the board as shown. Hope i burped her gas tank okay. I will do this again next fill up to make sure i get it right.
I used and have been using 85 octane and was getting in the mid to upper 40's before we started doing maintenance!
In the meantime, i raised the front tire to 38 (the cheap Falken Sincera rated at 40 psi) and the rear to 35-36.
I am now wondering about what else might be wrong.
Tune up, new fuel filter, well functioning injectors...
Could the engine cleaners be kicking up crud causing some other issue?
I've been reading about PCV catch cans, o2 sensors, MAP sensors, sticking EGR, air filters, fuel pressure regulator...i am trying to learn be researching others threads before I reach out so I dont waste Too much if your time.
i am trying to communicate w my trusted mechanic who is new to the potential of the VX, but is willing to listen and learn.

I have a massive headache, and am not in the mood to read, but are you sure you have the D15Z1 engine? The MPG your getting looks like a non- V-Tech-E engine MPG. Also tire pressure has a big impact, go 45-50 PSI. My RE92's are rated for 44PSI sidewall and I run them at 55PSI cold.

Hi. Thankfully confirmed the engine d15z1 at least.
Previous mpgs were in the mid to high 40's (High speed cross country and around town) This with tires set to the manual's psi. (35f, 33r)
I would love to inflate them 40 sidewall max if you think they'll still provide winter traction.
Trouble shooting-wise, better to wait until we figure out why mpgs are suddenly down.
Hope your headache is better. Thanks for helping...

I always try to listen for when the fuel starts coming up the neck so I can beat the auto shut-off but it is very difficult to do anymore because of the constant buzz of activity or the station has the outside radio cranked way up or there is an open-exhaust ****tard blasting by. :mad:

Understand, the first time you use the board it will give you a more complete fill and that will mean you will show lower mileage, but only for that single fill. Next fills should show you more realistic and consistent mileage.

regards
mech

Excellent note. Waiting between fuel ups tests while trouble shooting tests my patience. Should I let it get at least 1/3 down by the indicator or is it better to wait until I can do a more complete fill?

Did you consider getting a Mpguino ? I consider it invaluable to see the difference that leanburn, speed, tires, inflation pressures,gearing,wind,temps, driving techniques makes. Once you have it calibrated you don' t need to wait for a fill up .

I'd go at least 200 miles but it really makes little difference in the long term.

regards
mech

Please YES, but thats on my wish list and Im not sure how to install it or whom to ask. I would need patience(right 😊) & guidance.
I was happy w the 40's but am trying to figure out the drop into the 30's.
So many variables, so many miles to go.

Found a perfect pump at my mechanic garage! (and price if i use 85 which most folk say is fine.) having no idea if this happened in the past should that charcoal thing be checked?

Here's the update on my VX Pearl (as in Tahitian Green):-):
She suddenly and silently stopped working a block and a half away from home. I have video of the flatbed action.
So. I now have a new distributor igniter, ignition coil and the replacement cap is coming.
I am happy to give this car what it needs to thrive not just survive. That said. I am Not cash rich. I Need to save for a timing belt/water pump install.
In the meantime and for future reference, What is the cheapest but best way to purchase oem parts? Is there a reliable online dealer? Local dealer?
I expect to see mpg improvement soon!
I Promise to inflate my max 40 psi tires to 40 or higher :-)
Need to ensure air filter and trans fluid is okay.
My mechanic thought he heard slight tapping when he test drove it and wants to adjust the valves. (So many parts i hope i quoted the right one) ?
The questions:
What about installing an oil catch can and the three area Seafoam treatment Ive read about? If we are running the Bgs cleaners, could we be kicking up gunk?
Should I have him check cam timing?
Last for now:
Anyone in Colorado who'd help me install an Mpguino? :-)
Happy travels.

seems like you have a great gas saver but you truly have to start doing your own maintenance to save even more money. it's really not as hard as you think to change out a distributor or change fluids or even a valve adjustment.

Thanks for the encouragement. You Have read the progression of events? Mpgs in the high forties, tune up, then high 30's, replaced dead thermostat etc? :-)
I have since pumped up my front tires to 48 and the back to 44. Discount Tire r&b and their advice on psi based on the winter weather and our wide temperature swings.
I like my mechanic, but actually I was thinking if I had help with diagnostics, and a shop manual maybe I could try some things. I found an original shop book on eBay for $109. I'd rather spend that $ on parts or tools, but wouldnt it be good to have?
I don't have many tools, any experience repair. Patience is not usually my strong suit.
BUT I do have the motivation to learn the specifics for this special vehicle. I want my mileage back. Maybe there are settings that are off due to the maintenance done so far?
I did get one 47 after the tune up.
Sorry for all the words. Thanks for any thoughts. Michelle

A factory manual will save you money in the long run if your willing to do simple maintenance. A simple tool set at costco is less than $100. Or get a craftsman set when it's on sale.

Find a friend who knows how to work on cars and learn

Michelle,

I've found YouTube EXTREMELY helpful with basic and even more advanced maintenance procedures. There are many videos on just about any job you need to do on a Civic and since the Honda engines are so similar, you can get the basic idea by watching them. I have a Haynes manual but haven't looked at it much because I find the videos much easier to understand.
EricTheCarGuy is a mechanic and has many videos with Civics.

hi, i just need to make 5 posts so i can post a pic lol

Since my last post:
Bought an original shop manual and will find a buddy.
Previous maintenance appeared to have worsened gas mileage by 10 mpgs.

New dealer parts:
Timing belt/water pump
Fuel filter
Air filter
Valve adjustment
Oil change with MOA
Miscellaneous belts, o rings, oil pan gasket
Motor mounts, left and right
Set ignition timing with timing light
New air filter

I already had these:
The major tune up (I actually had one 47 mpg tank after)
Re-built distributor
New thermostat

I began to have trouble with the idle. After several attempts to adjust it I took her in for a dealer diagnostic.
Here's what they did:

Adjusted timing belt tension
Checked timing
Checked idle speed
Removed and cleaned throttle body, removed and cleaned idle adjust screw, adjusted per service manual procedure
They recommended that I replace the idle control valve.
I did but still had fluctuating tachometer readings, bottoming out even with lights out(factory tach, still need mpguino).

More new parts and cleaning with Seafoam
VSS (the speedometer went haywire after an undercarriage wash)
Thermo unit and thermo
Sensor assembly
Five wire o2 sensor (NGK 24300)

I took it back to the mechanic at the dealer tech for more diagnostics as suggested and to adjust that darn idle.

Here's his work and "verdict":
Checked EGR operation
Checked A/F sensor
MAP sensor
T/P sensor
ECT (TW) sensor
Set base ignition to spec (VX spec I hope)
Performed compression test (#1-128 psi, #2-129, #3-120, #4-130)
Re-set base idle 75 rpm higher than spec
Monitored PGMFI dat list with PGM tester and 3 pin data link adapter. All values within expected range
Ensured that PCM is getting A/C request signal

After all of this, he concluded that an engine with nearly 270,000 miles on it couldn't do better. Even though I drove it across the country and for two months in Denver getting 45-48. A quick drop from 47 to 37 leads me to think there's still something else going on.

I changed to Conoco gas and will run a couple tanks of 87, but am working through a tank of 85. Which by the way, I was getting the better mileage pre-cleaning, pre-maintenance on 85, but I will upgrade to what my book says. I don't know if that accounts for 10% ethanol, but the power was better and I got 44 mpgs over 350 miles, 2/3 at 60 mph, 1/3 short highway trips and city commuting.

Then I noticed hesitation when I let off the pedal and re-accelerate around the time the shift indicator light comes on.
It seemed to be worse when the tank was below 1/4. It also took a little longer to turn over. Next part:

New fuel pump.
Checked the clutch (it's fine)
Checked the oil (it's Much, Much cleaner)
Set the tire pressure to 44/40 (I can go higher if you advise)

What about trying this procedure to set the idle speed for 92-95 Civics I found? It involves resetting the ECU to VX spec under load (test load w lights only) 650-700 rpm, no load 550-650. Or does it sound like this was already done? This procedure is at garageninja.com:

Full tank.
Any advice before my next experiment?

Thanks folks. Sorry if this is overload information.
This same car here was for sale here in Denver. It was for sale, all stock, Tahitian Green Pearl, just like my car with only 67,000 miles. It sold for $9,000. It is getting average 52.

Those compression readings are very low for that engine. Throttle wide open cranking compression with all plugs out should porobably be close to 180-190.

regards
mech

Can that be remedied?

Just want to say I've read lots of your posts. You're very knowledgable.
Also Chrysler Kid recommended using Marvel Mystery Oil in a different post.
I have read that too much engine cleaners can damage the rings.
Could this be related?

What about Restore products?

Make sure the compression test is done with the throttle wide open and preferrably the plugs out of the other 3 cylinders. Cranks faster and gets full atmospheric pressure for the test.

If it's still that low you need the rings replaced and other work done depending on the condition of the cylinder walls.

regards
mech

I will have it re-tested. Why is one so much lower?
I just read your comments on "simple ring installation".
Best case/worst case what might that ring job cost?

Done right it's a big bill, been out of the business, In my old shop we were at $26 per hour when I bought it (the shop) and $65 when I left. Get a quote from someone trustworthy.

regards
mech

$3,000 engine rebuild sound "normal" or necessary?
Given the compression numbers, is this critical?
Would it explain my fuel drop?
Could the BG's cleaners have cleaned so well, they removed the gunk that made things hold together. (Removing the "glue"?)
I can drive my HX and save $ for VX.

"critical"as in continuing to drive it would damage the engine and all it's new parts and maintenance...

ATTENTION

I MESSED UP WHEN, I forgot about your altitude. 120-130 would equal 150-160 at YOUR altitude compared to sea level.

Forget new rings at this point, I don't think you need them.

No additive would mess the rings up unless it was VERY improperly administered.

I would suspect the O2sensor or clogged egr ports in the intake manifold.

There has to be good Honda specific tech in Denver and many members here have Honda specific knowledge far superior to mine.

regards
mech

http://www.healey6.com/Technical/Nom...20pressure.pdf

The chart on this linked page shows compression pressure asa function of compression ratio.

I think your engine is fine compression wise.

regards
mech

Get a couple fuel fills with the board under the left rear tire. you mileage calculations should be much more consistent.

The temp gauge needs to be just below half way up the gauge within 1.5 miles after a cold start or the engine is not getting warm enough. If it is working right, get a MPG reading from a couple of fills and run a can of chevron techron through the fuel.

Maybe a little road trip before the next fill and lets see what the mileage is.Try to fill consistently at the same station-pump.

regards
mech

As low as 100 will drive, but I'm at 4500' elevation, and up here we consider 140 as low and around 190 as normal for a high-mileage LSx V8. A new crate 5.7L V8 from Chevy cranks around 205-210 at sea level, so 120-130 is giving up an awful lot.
Go to Harbor Freight and get a $20 cylinder hone, go to RockAuto.com and order gaskets and rings, do the whole job yourself for under $300.
Also research the correct cranking compression for your engine back when it was new. If it wasn't near 200, then you'll likely also need to figure out what your engine takes to have earlier intake valve closing. Possibly adjustable timing sprockets, possibly much more.
Actually, research that first. Doing a re-ring is a good chance to swap in higher-compression pistons, possibly have the heads shaved, whatever.
10.0:1 static compression at this elevation gives the same results as 8.5:1 at sea level, so running 11.5:1 up here is no problem, and is better for MPG.

Thank you for the quick correction! I've been chasing down a chart I could understand and confirmation of the compression new and lower tolerance.
At coloradoevo.com-forums/showthread.php?t=4683
Dividing the test results by .853 confirms your figures.
What about that "120" though?
I will re-test at least that cylinder. Can it be improved?
I will also re-do your fueling as instructed. I didn't get the part about operating temperature.
Lastly, next time I fill up, should I switch to 91 octane?
I thought I saw that in the manual and the dealer tech advised it.