edit: just realized how vague my thread title is, sorry about that

Hello guys

I've been asking around about this but nobody I know has been able to pinpoint a solution.

I drive a 2000 Honda Civic EX. (not the main problem, but possibly related) For a while now, the car has been having trouble during heavy rain where it would stutter and have a hard time accelerating (would also throw a CEL which would go off after the rain stopped). Ran perfectly when it wasn't raining. I also had a lot of trouble getting the thing to start when the weather was extremely cold out (where I live the temp would occasionally drop way below freezing). Both of these things still happen, but nobody could give me a good answer and ultimately I never figured it out.

Fast-forward quite some time and the car has been driven rather roughly. Most recently the muffler was ripped clean off after hitting some mean train tracks with some heavy baggage in the trunk.

Main priority right now: CEL came on a few weeks later and has stayed on (albeit intermittently). Code P0420. That makes sense after the train track incident but I don't know for sure because I've heard so many different things about possible causes.

Symptoms:

- acceleration problems, car "hesitates" a lot especially in lower gears/rpm, shakes, stutters, etc. After the car has "warmed up", the problem goes away. No problem once it's been driven for about ten minutes.
- acceleration problems during rain; the more rain, the worse the problem
- o2 sensor code P0420
- hard to start during extreme cold (not sure if this is related)

Someone suggested that it could be a MAF issue, because those are supposedly known for throwing o2 sensor codes, but as far as I know 2000 Civics don't even have a MAF. It could obviously also be the o2 sensor but I'm not sure that this would cause the rough acceleration. And I'm not sure if trouble in cold weather and rain is related to the recent problems. Could just be the cat too but I have no idea and I don't want to get a new cat installed just because some other minor sensors are screwing up. The only reason I don't think it's necessarily the cat is because of the other underlying problems (cold weather, rain, etc).

I truly appreciate any advice

Thanks

 

is water getting to/into the distributor cap somehow?

 

This.

 

That makes sense while it's raining out, but would it be a factor with the acceleration problems I've been having in general? Thanks for the help.

 

The main issue is whatever's resulting in the p0420 and causing acceleration problems early in the day (even when there's no moisture etc). Could that still be a likely cause?

 

When was the last time you did a FULL tune up?

 

if it doesnt fully dry out and if the distributor is holding water, itll still run like crap

 

20k ago give or take

 

Not to sound like a smartass but would it hold water for days or weeks? I only ask because it's a consistent problem every day and seems to be unrelated to weather/atmosphere

 

Pull the cap off and find out. It is possible. Especially if it isn't sealed properly by the O-ring.

 

under the right circumstances it probably could, there doesnt have to be much moisture in there for it to run like crap

 

I'll check it out. Last bit, would it result in a code like P0420 at all? (Catalyst System Efficiency Below Threshold (Bank 1))

 

if its not sparking when it should and its not burning all the fuel going into the cylinder and its dumping raw fuel out the exhaust i guess it could, ive never had this problem on a honda before though so i cant really say for 100% sure if it is or not.

 

def sounds like a dizzy problem to me

 

I would replace O2 sensor first. Clear check engine light. If you get p0420 after that, then suspect converter problem.

 

Don't know who you've been talking to that can't pinpoint these small issues but maybe you should start talking to someone else.

 

im just going to point out the obvious but if there is a CAT on there check it as it might be clogged

 

^^ Check the dizzy first before replacing/inspecting an expensive *** cat. There are a few people on this forum that are certified honda techs and will give you the best advice. Just because your having this issue regardless of weather, your dizzy cap could be rusted to hell and not making a strong spark... And x2 what grumble said... This would be the first thing to inspect, and if your mechanic suspects otherwise, he obviously doesnt know what hes doing.

 

On my car it get pretty hard to start during rain, or after the rain, and I did notice that my fuel pump does not turn on/prime at that time. Couple of try, the fuel start prime and start like a baby, so on my issue probably water getting into relay somehow, but i park in the garage so It don't bother me that much to chase it down.

 

P0420 Code could be the secondary O2 or the actual catalytic converter.

As for the stuttering in the rain, check the dizzy seal. Also, what intake are you running?

 

Vague title edited.

 

I just recently had this problem (p0420) and I just replaced my cat along with a new exhaust system...car is running smooth and strong now. Good luck.

 

Thanks everyone!