92 VX Seeking 50+ MPG

[sokdo]

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.

[Lovemy92vx]

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

[sokdo]

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

[94VX]

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.

[silverHX]

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

[Lovemy92vx]

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.

[user removed]

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

[Lovemy92vx]

Can that be remedied?

[Lovemy92vx]

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?

[Lovemy92vx]

What about Restore products?