Something about this sounds just like the problem I had when I first got my 93civic. What I sugest you do to save A LOT of time: is just pull the main relay(right above your left foot near the fuse box), take the cover off of it and examine the solder points. If you look closely you'll see small rings in the solder when the pins come through. The Relay warms up with all the current running through it and what happens is the pins actually expands/gets longer (thermodynamics: warm objects expand) and breaks contact with the solder and circut board. So you wait while the car is off/won't start for a small amount of time and then it starts again. The solder points have cooled and made contact again!

This is a know problem with the older model civics. If you go to a dealer they'll sell you the main relay for the CRV(not sure if the new civics use the same one) to replace it with. However it's plug and play so no wire changes. OR you can fix it yourself by heating the solder contacts and wicking the lead away and resoldering the whole thing with new lead. This can be time consuming and may not work if it's another part of the relay that's shot.

So check it out and see if you have some broken contacts, it could save you some time and money.

 

would this cause it to run rich? I pulled my plugs and they were black. I just changed them about 3weeks ago, along with the wires, ignition module, coil, distributor cap and rotor.

 

I don't believe that a bad relay would make your car run rich. My plugs were clean when I pulled them when I had the problem. Spent a couple hundred dollars on parts I never needed. But the car runs much better because of that. You may have some clogged injectors, so I would sugest you put some injector cleaner in tank. Seafoam I hear works wonders. Someone else here might have a better idea on what is causing the car to run rich like that.

 

I just did the seafoam thing today. Hope that will clean it up a bit. The main relay that your talking about, do you just unplug it? or is it like a circuit board on a computer?

 

The relay is a little grey box with a single plug full of wires going to it. It's held on with a 10mm bolt. Simply unplug it, take the bolt off and it's in your hand. Then you can pop the cap off of it and check the circut board solder connections.

Oh and do a good highway burn with the seafoam in the tank, 200-300km should be good. I find if the engine is spinning at a good rate for awhile, the cleaner running through it does a better job by blowing out anything that is being removed. Then I let the rest of the tank go as I drive it around town.

But again this might not solve your richness problem, that sounds more like a fuel management issue that is way out of my league! You might have a bad MAP, O2, TP sensor. So many things could cause that. Only way to know for sure is to test your voltages against a shop manual. If only the computer would throw a code for that!

 

May have some fuel line clogged or the fuel filter can be clogged also...change it, see what happens...less than $12...

 

A worn out 02 sensor might also cause the car to run rich, but it should throw a CEL though...
You'r supposed to change them every 60,000 miles I guess even if its not throwing CEL's...expensive though...

 

I have a new 02 sensor and fuel filter. I tried to see if it would throw a CEL, but it didn't, which was weird because sometimes the check engine light would come on just before it cuts off. Could the charcoal canister have anything to do with it? I see a vacuum line hooked to it, but didn't notice any air flow when I unhooked it.

 

Charcoal canister??? What kind of aftermarket mods do you have on your car if any? I've never seen one in my car, is it part of an A/C system, which I don't have. We know that your Fuel/Air Ratio is not in balance, that's for sure. It just may be your Throttle position sensor, it's telling the cars ECU that the throttle is wide open when it actually isn't and it's dumping fuel into the engine. Does your exhaust smell like unburned gas? OR Did the car have a different set up before you owned it, such as a turbo or some heavy tuning where the ECU may have been modified to deal with a few pounds of boost?(ie: more fuel for the extra air) You need ask/answer these questions. Tell us about your car it's current set up and/or past set up, and it might give us some clues to the issue.

 

Yeah the canister is part of the EVAP system. As far as Mods, I have cold air intake, header, hight flow cat, catback exhust sytem, 10.2mm spark plug wires, O2 SENSOR PERFORMANCE CHIP. Just did a tune up, changed the plugs, rotor, distributor cap, ig module and coil, fuel filter, O2 sensor.