Fixing a misfire during acceleration in a 1992 Honda Civic

I took some packages to the post office today, and was surprised to find my 1992 Honda Civic was having a very bad day. It was misfiring during acceleration at low-mid RPM. Idle was smooth and cruising was fine, but any normal amount of acceleration from a stoplight or stop sign produced an extremely loping, uneven amount of power. The car was drivable, but just barely.

I took out a couple spark plugs, and was surprised to find the gap had become huge -- around .075"! The plugs appeared to be worn out. I figured this had to be problem. I got some new NGK plugs, and unfortunately the problem persisted. I checked the compression in each cylinder, and they were all 150 psi +/- 5 psi. After a short consultation with my dad, I decided to replace all of the common ignition parts with real Honda replacements: distributor cap, rotor, and plug wires. This did the trick! The car was back to normal, and running strong. The original cap and rotor were Honda parts, but the plug wires appeared to be aftermarket (Prestolite). Dad and I agreed that aftermarket plug wires should be avoided altogether. Just bite the bullet, and buy OEM wires. They'll last much longer.

Even though it is difficult to see in this photo, the old plug (right) has a gap almost twice that of the new plug (left). This too-large gap in all four plugs might have contributed to the destruction of the plug wires.

Replacing a Honda Civic condenser fan without draining the freon

My 1992 Honda Civic recently developed a strange problem where the engine would idle badly and sometimes stall when the air conditioning was being used. Oddly enough, the problem turned out to be a non-functional condenser fan. Presumably, the compressor would pump the high side of the system up to an abnormally high pressure because the system was unable to dissipate heat from the condenser. Eventually the mechanical load from the compressor was so great it would cause the engine to stall. I would have guessed there was a high pressure limit switch that would deactivate the compressor, but maybe not.

In any case, this is an R12 system, and I did NOT want to open any of the freon lines. It had been working great ever since I bought the car (until this recent problem), and I did not want to mess with it. Luckily, it's possible and not too difficult to change the fan motor without opening the freon lines.
The fan shroud is bolted to the condenser with two 10mm bolts near the top facing into the condenser. There is also a small bracket on your left that has two 10mm bolts to hold the bracket to the condenser and shroud. I removed all four of these bolts, two bolts that held the shroud to the car's frame at the top, a bolt that holds a freon hose to the shroud, and also a bolt that holds a relay to the frame (on your right).



The shroud can be lifted up and out of two pockets that are formed into the metal of the condenser. It cannot be fully removed from the car because there is a freon hose in the way, and the hose cannot be moved. Instead, I removed the plastic rock guard on the underside of the car, and slipped the shroud out through the bottom. There are a few wire-guides and connectors on your right that need to be removed before the shroud will clear the car. I didn't even need to jack the car up.



Once the shroud (and fan) were out of the car, I switched the motor with the new one. Do NOT forget to also move the tiny washer from the old motor to the new one, which tends to stick to the old motor shaft and fits so tightly it almost looks like part of the shaft itself. I made this mistake and it nearly ruined my day. Without the washer in place, tightening the nut will cause the metal hub of the fan to be pushed in a bad way so that it is no longer engaged with the shaft. Since there is no other way to grab hold of the shaft, you are left with trying to get the nut back off and no way to stop the shaft from turning. After fiddling with it for a long time, I remembered my dad recommended the use of a pneumatic impact wrench in situations where a nut must be removed from a free-turning shaft. The idea is that the impact wrench hits the nut so hard and so fast, it is able to back it off while the inertia of the shaft holds the part still. Lo and behold, it zipped the nut right off. Thanks, dad!


The rest of the job was pretty straight-forward, and now my air conditioner works like a champ and doesn't stall the engine.

The old motor appears to have died of old age. There aren't any catastrophic problems, but the brushes and commutator show heavy wear. The motor case was full of carbon dust from the brushes.