1994 Honda Civic Stumbling

"Alan" wrote in news: snipped-for-privacy@z34g2000cwc.googlegroups.com:

Considering that Honda/Acura autos are known for failing ignition coils,this would be a good place to start.

.......A bad O2 sensor will not necessarily set off a CEL on a

1994 Honda (pre-OBD2). Since the problem occurs after warmup, that makes me especially suspicious of the O2 sensor. has the bestprices I've seen for OEM O2 sensors: About $69 altogether. Ihave used them. Good, prompt service. Maybe not a badinvestment for a car this old. Elle, I went to this site, & an O2 sensor for my 94 VX is $289.99. Before I spend this much money, what symptoms would I be seeing?

.....Purge cooling system thoroughly of air. Follow the manual's instructions. Getting the fan to come on may take as much as 40 minutes of idling. If various ECM sensors aren't cooled properly, then this may cause erratic behavior.

I'm following the manual for a 92 Civic, & reference a 95 PDF which is identical. I've pulled & cleaned the reservoir, then replaced. It appears the radiator drain plug turns counter clockwise. Any hints on how to get it to move without breaking it?

I started the car, put the heater temp control lever to max heat, then shut off the engine. No mention of whether or not to have the fan running while I purge the system. Any ideas? I'll top up the fluid today, then once I can get the drain plug to move, do a complete refill.

I've tried bleeding before, but had the cap completely off. Manual says to put it on to the 1st stop. I was still getting the erratic idle at a stop with this approach.

Oops, sorry. The 94 Sensors seem to be far less for any Civic that is not a VX.

Still, this price beats

, at $340 + s/h.

If after performing a tuneup (new plugs, possibly new ignition wires, new distributor cap and rotor, new air filter, new fuel filter, check timing), the stumbling and/or poor gas mileage continues, I would consider a new O2 sensor.

Yes it does. The usual rightie-tightie lefty-loosy threads.

IIRC sometimes it's very tight. I have used a pair of pliers on its end to get a good grip.

Might be a good idea to buy a spare from your dealer in advance in case it does break. Though I haven't heard of one breaking.

Leave the passenger car fan off.

I would perform (and do perform) the bleed with the cap completely off. I too noticed a similar discrepancy between what's in my Chilton's manual and what's in my owner's manual for this procedure. I see the service manuals at the site below say to leave the cap completely off for the CRX. (I think the Concerto manual has a typ-o on this point.)

It makes more sense to me to have the system under the lowest pressure possible so as to encourage air to escape it.

Try the Concerto manual at

under "Fuel and Emissions" then under "Idle control system," for other things to check, especially the Electronic Air Control Valve. This group gets a few reports of this failing every year (assuming the air purge above doesn't fix the problem). Can you clarify: Is the car both stumbling while accelerating and has an erratic idle?

"Elle" wrote

I meant the "passenger compartment blower" should be left off.

Elle wrote: ..... Can you clarify: Is the car both stumbling while accelerating and has an erratic idle?

Acceleration is fine for a VX. It's sitting at a light, or stop sign with all accessories off. The car doesn't die, but the idle tends to drop low enough that I think it will. Turning the fan on to it's lowest setting stops this, but thats just masking the problem.

I bought it in August. So far, I've replaced the plugs & wires with OE. Put on an after market fuel filter. Honda dealer replaced the timing belt & water pump. I've added an after market cruise control. Not sure if it would cause any trouble. I've had them on all my other 3 Civics. Just passed 200K on a trip to Texas. 40+ MPG since I bought it.

I went ahead & replaced the Antifreeze today. Careful use of some water pump pliers loosened the drain valve. I'll keep a close watch on the overflow reservoir this week.

30+ miles each way to work, so hopefully any remaining air will be purged.

This doesn't sound like the oxygen sensor.

It is worth checking the ignition coil, especially if this occurs after the engine is warmed up, like after 20 minutes of driving. An older ignition coil will be persnickety at idle, especially at warmup. Ultimately it will fail completely.

See info on checks you can do on the coil at

I would replace the cap and rotor, too.

Put on an after market fuel filter. Honda

I'm not sure that's the same as getting the car temp up high enough to get the fan to come on twice, with the rad cap off.

I changed my 91 Civic's thermostat in March 04 and did not do a proper purge. I started having idle problems around July or so. I found the cooling lines to the EACV empty. It seems to be a high spot. A proper purge fixed the problem.