Hello All,

I'm have problems with a 1992 Civic VX I bought for my son. A quick history, it had a blown head gasket when I bought it. That's been repaired properly but when I went to get it smogged here in Ca. it passed the 15 mph test but not the 25 mph test. It would hold the 15 mph in 2nd gear but wouldn't hold the 25 mph in 3rd so he tried it in 2nd gear.

The smog tech told me to replace the O2 sensor and do a tune-up on it and to look for vacuum leaks as the oxygen on the test data was high. He said that driving it after the blown gasket probably contaminated the sensor and after doing the work to drive it for a while to allow the ECM to recalibrate to the new hardware.

When I drive the car it has great acceleration, it idles perfectly and runs great except at low sustained rpm like on freeway 4th or 5th gear at speed. It seems like it's running fine then feels like it's slowly dying, if I press the pedal it'll pick up with a jerk and take off but then just do it over and over.


Some of the things I've done to the car are, I placed the O2 sensor, I did a tune-up (cap, rotor, plugs, fuel filter, air filter) set timing, idles at 610 rpm. I've checked the following sensors for function, speed sensor, throttle position sensor, Idle air compensation valve. I've removed and cleaned the idle air compensation valve. I've searched for vacuum leaks and found none. There are no codes in the ECU and I've disconnected the battery to clear the the ECU and have driven it to "teach the ECU. Nothing seems to work, I need HELP PLEASE!!!!

What I'm looking for is, is there anyone on this forum that has some knowledge of the VX drive train and driveability that can help me do some trouble shooting or point me in a direction to head!!! Thanks for any help!

Take Care
Troy

 

Clean out the EGR system, if it has one. The passages under the plate on top of the intake manifold get clogged with carbon. Mostly you just fail smog (high NOx) because of that.

 

Thanks for the help, my son cleaned it while it was apart but I'll give it a check myself.

 

Does anything change when you unplug the O2 sensor? A CEL will come on, but my issues (when I had the VX last year) went away once this was unplugged. How many wires are in the replacement o2 sensor you installed? J/w

 

I haven't tried unplugging the O2 sensor, I didn't think it would run! I'm new to these imports. The sensor has 5 wires, it's the $300 one. I'll try disconnecting it and driving it. Thanks for your help it's very much appreciated!!!

Take Care
Troy

 

Well we unplugged the O2 sensor, and the car runs great! I just put a new o2 sensor into it a few hundred miles ago. If I didn't need to pass smog I'd leave it like that and just drive it. Does this seem to indicate that the O2 sensor is bad or is there something else that could cause this problem? Thanks for any help anyone can give us!!!!

 

see post #6 Can anyone explain this to me. Is it a bad O2 sensor? Or does it point to something else?

 

Sensor unplugged makes it run "open loop" where the mixture is generally richer than it should be. This generally runs better but it wastes gas and increases HC / CO pollution.

 

But is there a fix for the problem when the O2 sensor is plugged in? I'm trying to get this thing smogged and I can't with the O2 sensor unplugged.