1993 VX ideling questions
 

Just bought a stock Vx and have some issues that i'm hoping to resolve. The idle is slightly rough, and coughs occasionally when accelerating. Also when screw the idle adjusting screw higher and then rev the car the rpms dont wanna come down until i screw it back to the low idle. (btw what should the idle be for a 93 stock VX?). I tried checking for vac leaks (dont really know an accurate way) and cleaned the IACV. Looked for the FITV to clean it and didn''t know how to locate it. Does this car even have a FITV? My other problem is my horn isn''t working, it just makes a click sound; where is the horn located?

a complete tune-up might help the idle

Might need a new IACV. I had bad IACV in mine - idle would go up and down all the time. I tried the usual - tune-up,O2, EGR/IACV cleaning - nothing helped. Then I swapped IACV out of a junkyard engine and now it's good at idle, but still bounces when the the car is coasting in neutral, so a new IACV might be the way to go. Ross

You can't just play with that screw. Adjust it according to the repair manual. Basically, you start the car, unplug the IACV, then turn the screw until the RPMs are within the spec it gives you which is a few hundred RPM lower than normal idle (you need a tach tool that connects to the diagnostic port near the brake resevoir). Then you reset the ECU.

This year Civic is notorious for loping idle. There are some very good topics over at Honda-tech and other forums that cover all the bases.

As for your horn question, go to:

https://www.hondapartscheap.com/southbay/jsp/prddisplay.jsp?hidSwitch=Switch&hidIrno=|008&catcg ry1=CIVIC&catcgry2=1992&catcgry3=3DR+VX&catcgry4=K A5MT&catcgry5=CONTROL+UNIT+(ENGINE+ROOM)&vinsrch=n o&ListAll=&prdrefno=&act=&count=0&quantity=0

You will find the horn is item #8. It appears to be located behind the front bumper on the passenger side.

I also have a similar problem with my idle. It runs a bit rough, with some intermittent puffing. I had an ongoing CE light issue previously; I solved that with a new O2 sensor, which improved my mpg to 46 from 40. However, other VX owners report around 50 mpg on this forum, so maybe I too have an IACV issue.

"other VX owners report around 50 mpg on this forum"

I once did a careful review of all the VX gaslogs here (about two dozen). Typical overall mpg is about 45 mpg. But most owners have at least some tanks over 50, and occasionally you see results over 60.

Here's something very obvious but still sometimes forgotten: driving conditions and driving style make a very big difference. So depending on those factors, 46 mpg might actually be a very good result.

I agree.

I'm a vx owner and at first i couldnt get much more than 40 mpg out of my VX. Once I improved my driving style and got used to the VX power-band and gearing, I improved my MPG in city and highway driving.

I have a friend who had a vx and he could barely ever get 40 out of the car but i would assume this was mostly due to driving conditions and driving style since the car was properly maintained and the previous owner claimed to get high 50s with the car.

I found that the pcv hose gromit tends to dry out and become a vacuum leak, it's hard to get to as it's under the intake manifold, o2 sensor should last 10 years or 200,000 miles and will cause some hesitation.
I get around 45mpg but I also live in a hilly area with alot of stop signs at the bottom of hills and I tend to use my vx as a work vehicle so I haul stuff and people with it and take the electric car for lighter trips, and mine also has 251,000 miles on it but it is still running strong, a friend is currently using it and was blown away by the smoothness and the power.

I am a pretty consistent driver. I always drive with fuel economy in mind; the only time I will push RPM above 3000 is when I need emergency acceleration. My rule of thumb is "under 2000 RPM when cruising, and get to the highest gear possible". This of course makes the engine turn slower, which keeps fuel economy high.

Right after I changed the LAF (O2) sensor, mpg jumped from a steady 40 to around 46-47 mpg for several fill ups. My last tankful averaged about 42 mpg, and I have no idea as to why - I didn't change my driving habits at all.

I would like to do whatever I can (within my financial constraints) to boost my fuel economy as much as possible. Would replacing the EACV (that's what Honda calls it) increase fuel economy, in addition to solving the rough idle/puffing issue?

"My rule of thumb is 'under 2000 RPM when cruising, and get to the highest gear possible'. "

That sounds really good. But you didn't mention coasting (P&G). It can be worth a lot, even if you can't manage to turn the engine off.

Also, your driving style sounds good, but you didn't say anything about your typical driving conditions. 50 mph is a lot different than 75. Also, short trips in heavy traffic will hurt a lot. Likewise for lots of extra weight in the car.

"46-47 mpg for several fill ups"

That's a pretty typical and respectable result. Evaluating it as good or bad depends on the conditions.

I'm also curious about your tires (model, size, pressure).

"My last tankful averaged about 42 mpg"

I'm very suspicious about drawing conclusions from one fill. I think there are too many reasons why the number could be misleading or unreliable.

"would replacing the EACV (that's what Honda calls it) increase fuel economy, in addition to solving the rough idle/puffing issue?"

I don't know. Maybe someone else will chime in with regard to that particular question.