Stock idle speed is 600 +/-50. You need a diagnostic tach because the stock tach just isn't accurate enough.
Any small vacuum leak or bottleneck under the hood of the VX will cause a driveability problem ranging in severity from a slight hesitation to serious bucking. It's a result of Honda pushing this car and it's technology to the ragged edge for maximum economy. That is why the VX got very low reliability ratings compared to the rest of the Honda lineup; which in turn motivated Honda to perfect it's system with the introduction of the HX (lots of backup strategies and self diagnosis).
The O2 sensor was stamped NTK L1H1, and seems to be working fine. The sensor appears to have been repackaged by a domestic company out of Long Island City (can't remember the name and I don't have the package with me). Thanks for the confirmation on the idle speed, I will confirm it with a diagnostic tach and double check for vacuum leaks.
I'm not as tech savvy as some of the others on the site are, but I can tell you that I had similar issues to what you've described with my 92 VX for a couple of years before I found this site. The guys chimed in with the "replace the O2 sensor" proposition. I followed their advice, changed out the sensor (even though I paid more than I should have for it), and the car behaved much better immediately. The moral of the story for the VX is that O2 sensors on these cars do tend to go bad after several years, and the device is a major part of the VXs outstanding fuel economy.
Another device that can affect how a VX engine runs is the Electronic Air Control Valve (EACV), which sits at the top of the engine between it and the firewall. The EACV can get clogged or dirty, and this can impact idle rate or make the engine idle rough. There are links on the site as to how the device can be removed for flushing out with brake cleaner. You can also get replacement screens, etc. From OEM Honda parts websites such as Bernardi Honda.
One more thing: make absolutely sure you have the correct spark plugs installed in your VX: they are not the same as those used in other Civic models. Use NGK V-Power Plug #ZFR4F11. If you use others your car can run much worse than it should.
Simplicity is the glory of expression.-Walt Whitman
you can also slip your finger under and into the egr valve and manually open it to check that it moves freely and evenly...
holding it open at idle will make the car stall
but you can play with it a little...
Hi i'm a new member from Qu?bec city in Canada...same problem...my car is ultra clean, but i still have iddle problem...up and down...between 900 rpm up to 13-1400.rpm...and goes down...and when try to accelerate seems to loose power...i have to press more...and feel a kick and accelerate...???parts changed..NEW...EGR, AICvalve, oxygen sensor, intake gasket, temp.sound(gauge)new tps...only the throttle body is change but for another used...so maybe? by the way my VX is a 92, with 207,000 KM...yes we are ine kilometers...please help...thanks
almost 300k kms on my original engine. did all the tune up stuff but still has the slight hesitation.
the power does not come on smooth when the engine is warmed either. like if i go 20% throttle to slowly speed up, there will be a flat spot in power... then, power will kick in. it's quite annoying.
the emissions tester did say that i have a little exhaust leak... and that can cause a/f ratios to fluctuate due to incorrect o2 readings. i think i will tackle this first. PITA to remove hot parts though!!! ughh.