I just picked up a 1992 VX HB, a bit over 183K on it. Car runs well, now,and power as well as gas mileage has doubledfrom the time I first purchased it; with a little work after learning thatthe timing had jumped two teeth and it hadthe wrong distributor installed. I have since replaced the timing belt, water pump,brand new distributor, distributor cap and rotor, plugs andwires, fuel filter, oil and filter, cleaned carbon out with 44K, and new coolant. One naging problem remains, however. I've noticed that the car runs great--right up to the very second that it reaches operating temperature (OPTEMP). At OPTEMP it develops a shutter, especially under light gas pedal pressure--as if it's runningtoo lean. Not too noticable upon acceleration, mainly at cruise speeds and light pedal pressure. Before it hits OPTEMP, no problem. No engine check light. Any ideas? Thanks!

 

I have a '92 VX as well that has the exact same problem. We brought it to a shop, they thought it was the O2 sensor so that was replaced (expensive on this car) but that wasn't the problem. I believe this problem is causing the car to run rich rather than lean. I remember prior to the problem existing that I could average mid to upper 40mpg on the highway, and after a recent trip only was able to average about 36mpg. Also the exhaust smells like it's running rich. I am going to check plugs tonight to see what they look like. They should indicate if the car is running rich or lean.

Additionally since the problem only occurs once the engine has reached operating temp, it tells me that it is most likely a sensor. As far as I know, when the car is cold (below operating temp.) the emission system is running closed loop(not using sensor outputs), but when it reaches temp switches to open loop and starts taking info from sensors andadjusts things like fuel/air mixture and timing advance to achieve proper operating perameters. I have a manual for the car and I am going to begin checking sensor tolerances and update with my progress.

In the mean time, if anyone has anything to add it would be greatly appreciated.

 

Thanks for sharing your experiences, very much the same at this point on my end. Considering what you said in your post yesterday, I decided to try replacing one of what apparently are three heat related sensors--though there may be others. Since the problem appears to betemperature related, I started by narrowingit down to perhaps a few related heat sensors. I was told by my always trusted OEMparts guy at one of the local Honda dealers that one sensor exclusively controls the gauge on the dash; another is exclusive tothe cooling fan's operation; and another--which he agrees may be a best guess--is something Honda calls the "TW Sensor."

The TW Sensor apparently provides engine coolant temperature information directly to the PCM, which in turn decides fuel and other distributionsneeded to make these babies do what they do. I'm taking a chance that this is the problem and ordered one yesterday. You can find them at local parts stores under the title ECT (Engine Coolant Temperature) Sensor for about $28 with tax; Honda sells for $34 and some change. This little sensor is located screwed into the head/engine block near and to the right of thedistributor--if looking at the engine compartment from the passenger side fender. I'll have mine later today, give the engine a chance to cool down, and try replacing it before heading home from work today. Will update the findings.

 

Well, save yourself $30... replacing the TW Sensor may have beena good guess but didn't solve the problem.

 

You beat me to it.I was going to tell you that mine had just been replaced as well and that wasn't the problem. Is your check engine light on? Mine is not, andhas not come on since I have been having this problem. It came on while the O2 sensor was bad but has not come on again since the O2 sensor was replaced.

I was told of a shop in my area that specializes in Honda's, and the owner is the type that is willing to talk over potential problems rather than just taking the car and charging for extensive diagnostics. I am thinking of running over and giving him a try and see if any light can be shed. I will keep you posted.

 

Nope, no light here either;which is something that baffles me, since most things that negatively affect the vehicle's operation are monitored by the computer--is whatI'm thinking. I talked to a few folks, largely generalist,and have been given very good suggestions, which run the gamut. Everything from the Throttle Position Sensor (TPS) to the Engine Control Module--to “man, that’s just the way Civics run!” I haven’t given up. I too need to find a specialist maybe willing to share info or someone that experienced same problem.IfI happen tohit uponthe fix before you find something, I’ll be sure to post.

 

Okay, now I'm 'bout to just give up! I ordered and installed a new TPS but the hesitation/surge problem continues. Here’s something strange that I discovered as I try to make a diagnosis of the possible source of the problem… I decided to go with the TPS replacement because when I unplug this or the old TPS, I get a glowing CEL (Code 7) but the hesitation goes away completely. Of course without the TPS connected, the car has little to no power, not as if it has a lot to begin with, and gets horrible MPG. Plug it back in and hesitation returns the very second the engine reaches operating temperature. The hesitation still only occurs with slight pedal pressure at cruise speed. At idle or standing rev, everything seems to bejust fine, no CEL.

Anyideas? Thanks.