My advice: Get rid of those plugs ASAP!

Those are NGK Iridium ZFR5F-11s, they are not meant for a lean burn motor and can potentially damage the D15Z1 combustion chamber.

The iridium tips are too small and the combustion temps gets pretty high when in lean burn, this can melt the tip off and cause damage to piston rings, valves, and cylinder walls.

Go get yourself some NGK V-Power Spark Plugs No. ZFR4F-11 copper plugs, no iridium, or any plugs with more than one ground terminal, lol.

Bring 'em home, let the head cool off if you drove your VX to pick up the plugs, pull out the iridium ones, clean them off and sell them back to the ricer that owned the car before you and thought that they do anything good for the car. That way you can probably pay off the cost of the NGK V-Power plugs. Install the V-Power plugs and you should be good. Double check the condition of the spark plug wires. If they aren't the stock ones (i.e if they are aftermarket or "race" plugs, other than the NGK Race plugs) save up and get some OEM ones from the Honda dealer. Also check the condition of the cap and rotor. Replace if worn.

Doing that should help along with making sure you are using the proper driving technique for the VX.

And also check out the links in my signature and CivicVX.com for more info than you can shake a stick at for the Civic VX.

Good call. I just changed the ECU to the Fed one on my Cali VX and I didn't check the spark plug range. I just ran outside, everything is OK!

TomO,

I already got rid of those plugs and replaced them with the right ones from the info on your vx thread. Already did the cap and rotor, and it has new NGK wires. Atleast the previous owner got the wires right.

I would love to know what you think of my O2 readings, and what anyone else gets as their readings.

I am currently up to 38mpg.

Background info:
90% highway driving, 100 miles a day
Average speed is 55-65mph
I don't drive like a hypermiler, but i do get passed alot
No CEL on
It is a california car, has the l00 ecu but has a 5-wire o2 sensor. Apparently this happens sometimes on the 92 models.

We do the exact same driving, with the exact same car ('92 California VX). I've owned the car about a month. My first tank netted me 51.7mpg, my 2nd tank was 53.2. I try to stay at 60mph on the 2nd tank. I don't do any key off coasting, hit traffic occasionaly, with some hills. I don't know how many miles are on your car, but the compression numbers look good. Timing can greatly affect mileage, so I would look at it. Only thing I can think is how are you figuring out your mileage? Is there anything on the car that is not stock? Like headers, or maybe a transmission swap?

Also, did you check vacuum?

I wish i had those mpg numbers.

It has around 200k miles on it.
As far as i can tell it's the right vx transmission.
It is lowered and has an aftermarket rear spoiler, picture posted above somewhere.
I will check vacuum.

You can tell from rpm if the trans is right. At 53-55mph the tach is right at 2,000rpm in my car. I'm really curious as to why your car gets lower mpg. Someday my mileage might fall off and I don't want to be scratching my head for a month.

At 2000 rpm I'm around 55-60, which from what I've found is normal.
Hopefully this weekend I can get some more figured out. I leave for work in the morning when it's dark, and i get home when it's dark so working on it is a little hard.

Timing was retarded a bit, set it back to normal, no change in mileage. I'm still at 35-38 mpg.

What was the vacuum reading?

The last few tanks have been about 41-43 mpg, getting closer...
I'm going to take off that aftermarket spoiler and see if it helps, i know it can't be doing me any good.

I've seen the write up for cleaing the egr ports on the intake manifold, but mine look to be soldered up. Is that normal?