92 VX bad milage

[noender]

i just bought a 1992 VX and the gas milage seems pretty low around 30ish. i just did a spark plug change to the original since it had the wrong ones, also replace the pcv valve. im about to replace the fuel filter around this week. also the car needs and alignment i dont know if that affects the mpg alot. also tire pressure set a 34psi all around. any ideas or tips?

[vxdude]

change oil and air filter, plug wires okay? Valve Adjustment is a must!! The pcv valve should be hollow. Tires should be max sidewall pressure. How many miles on it. make sure you have oem transmission. I shift at 1500rpm. I have never been over 2k

[theholycow]

Misalignment can certainly reduce fuel economy. I'm not sure it would have a huge effect, though certainly measurable.

Is it the Federal or California VX? IIRC the CA one doesn't have a Shift Indicator Light and the Fed one does. If equipped with the SIL, do you obey it?

Having the wrong plugs implies one of these potential scenarios:
- Carelessly or cheaply installed whatever plugs were around; what other careless shortcuts/cheap-outs were taken?
- Trying to modify car for performance; what other modifications were attempted?
- Trying to compensate for another problem; what is the problem, what other damage might it have done, and what other problems/hacks might exist?

I'm not saying that one of those scenarios must be the case, but it's something to consider when you're looking at a severe loss of fuel economy.

How is driveability? Does the engine run well and feel as strong as it should?

Do the brakes drag? Jack the car and spin each of the wheels (in neutral for the front wheels).

Do the wheel bearings drag? I don't know how to test this. The usual wiggle test only detects one failure mode.

Of course you can do all the usual things that improve FE on a car that's working right (increased tire pressure, driving techniques, etc), but it sounds like something's probably wrong.

[add|ct]

Originally Posted by vxdude

change oil and air filter, plug wires okay? Valve Adjustment is a must!! The pcv valve should be hollow. Tires should be max sidewall pressure. How many miles on it. make sure you have oem transmission. I shift at 1500rpm. I have never been over 2k

This has been found to be incorrect. There is a separate location for the actual PCV valve itself, not the hollow elbow as previously was believed.

It's located, and accessible to some with smaller hands(me), from the driver side by reaching underneath the intake runners where the 'elbow'(which should be hollow) is and there is the actual PCV valve mounted sideways inside of a breather box.

To be clear, this is the end of the tubing from the intake manifold which includes the hollow elbow in question(between the runners for cylinder 1 and 2), following down below that onward towards the passenger side of the vehicle; underneath the intake runners themselves. The newer VX models; 94/95 IIRC, may have the hollow straight line pipe version at this breather box location and an actual valve at the suspected 'hollow' location. If you have a hollow elbow, it's probably correct and you need the straight, in-line, PCV valve located at the breather box.

In either case, only one PCV valve should be installed. One for either location only. On my vehicle, the hollow elbow was along the intake runners and following the pipe below that, I found the actual valve itself seated into this breather chamber/box. Covered in grime and hard to see; as well as get to with easy.

[imzjustplayin]

Originally Posted by vxdude

change oil and air filter, plug wires okay? Valve Adjustment is a must!! The pcv valve should be hollow. Tires should be max sidewall pressure. How many miles on it. make sure you have oem transmission. I shift at 1500rpm. I have never been over 2k

Wrong.. He should use a normal PCV valve and give the car a regular tuneup. There is no such thing as a 'hollow' pcv valve.. instead this is a confusion that arose out of a misinformed poster on ecomodder.com who confused a vacuum hose joint with the pcv valve itself.

As for op, redo all electrical grounds, scrub the bolts/washers/eyelits thoroughly, blow out the holes the bolts screw in since there will be dirt there, get a multimeter and measure the ohms value of each ground to the battery ground cable, trying to get the ohms down to zero. lightly scrub the threaded hole for the o2 sensors since there is likely rust in there. check the ohms value of the body of the o2 sensor to battery ground to see if it's zero or near zero ohms, adjust valve lash, clean EGR box, clean/repair clutch switch which is also used to adjust pedal height, replace ALL FLUIDS, check for dragging brakes/wheels, clean throttle body thoroughly (little passages like under the idle screw, etc.), clean IACV (for bouncing idle), replace PCV valve and frankly replace all vacuum hoses, check the ohms value of the ignition wires, maybe check whole ignition system to make sure that you're getting strong spark, replace ONLY with OEM recommended parts...

Remember this rule, use Japanese parts on Japanese cars and European parts on European cars.. So Denso=Japanese, Bosch=European, etc.

And finally....
Read this entire thread: http://www.gassavers.org/showthread.php?t=12045

[benfrogg]

Yes, your thread title and situation is much the same as mine was when I first bought it. It's a LONG read, but you will hopefully learn a lot from it about why your FE is not stellar. These cars are actually very sensitive to problems, modifications, etc. They are among the most difficult of the hondas to get the best FE out or, but have the greatest potential for the best FE of all hondas when they are in top condition. (excluding the insight, other hybrids)

http://www.gassavers.org/showthread.php?t=12045

If you have any questions afterward, please feel free to ask. Check my gas log as it corresponds with the discussion.
Good luck!
B

[bowtieguy]

Originally Posted by vxdude

Valve Adjustment is a must!!

i'm thinking this avenue in my disappointing LX.

[noender]

Originally Posted by vxdude

change oil and air filter, plug wires okay? Valve Adjustment is a must!! The pcv valve should be hollow. Tires should be max sidewall pressure. How many miles on it. make sure you have oem transmission. I shift at 1500rpm. I have never been over 2k

oil, air filter and wires look new. valve adjust i though it since the motor isnt making any ticking noises or misfires. ill adjust my tire pressure more hopefully it helps. the car has 200k + but the guy said he rebuilt the engine and it sure does no oil leaks or any funny noises .

[noender]

i have the CA version also the oem transmission i dont have the shift indicator. also went i went to smog it didnt pass it. the guy at the shop it could be cat converter could be plug. would this affect my gas milage?

[imzjustplayin]

Originally Posted by noender

i have the CA version also the oem transmission i dont have the shift indicator. also went i went to smog it didnt pass it. the guy at the shop it could be cat converter could be plug. would this affect my gas milage?

do you have the smog reports? Maybe you could post up your results so we can interpret them.. But if I were you, I'd just take the advice given in this thread and many other civic vx threads and run with it. Mechanics love to suggest the catalytic converter because it's an easy job and will always let a car that fails smog pass smog so it looks like a job well done.. I don't believe in that philosophy and think one should get a car in tip top shape before replacing the catalytic converter for a few reasons. If you can get the car into good enough shape, that might be enough to squeak by on the emissions test despite a bad catalytic converter, giving you more time before you have to replace it. It's better to spend $600 getting a car into a proper tune and operating condition than to spend $600 on a device that will do nothing for the longevity, maintenance or reliability of the vehicle just so you can pass a test. Replacing with a new catalytic converter before anything else could mask a problem the car has but you now don't know about because the new cat does its job so efficiently.