Engine is idling rough, especially with AC.
 

I have not spent too much time in the Phoenix area and I have mostly driven Dad's Focus SFE, which probably explains how I managed to drive 1,200 miles without a repair. Chorizo mostly sat for two months. When I was home, I needed to park the Focus in front of the Civic, and I did not take the time to shuffle my cars around to take the Honda for a drive.

So, as I mentioned, the engine seems like it idles low, for a moment it sounds like it will stall, but it revs, so at stops, it keeps going from 4-600 RPM. Then I realized that my registration expired while out-of-town, at the worst possible time! We do not have any idea where that notification went! Apparently, it expired after nine months because the previous owner's emissions ran out, even though I registered it with my parents' address, where they do not do emissions testing.

Yes, they can ticket you for that. Fun.

They towed my car, I got a temporary registration, got my car back, and passed emissions even though my car was idling rough. Halfway through my three-day registration, I register for two years, giving Mom's address, because I was about to drive up, but it says it will take five business days.

Print off receipt, put in car, load up, and I have a check engine light.

The guy at O'Reilly checked the code and said my downstream oxygen sensor was faulty, but it could be the fuse.

There is not any relevant fuse.

The guy at Autozone prints me off something and shows me on the computer that it could be the sensor or a loose connection. Mom had my socket set and I hate jacking up my Civic, so I go to a place called U-Fix It, where you can rent a bay and tools. He reads the code with something that looks far more expensive, and it says that my upsteam sensor is bad. He gets another reader, which also looks expensive, but does not show any codes. He turns off the light and tells me to drive until it turns back on.

A hundred and sixty-five miles later, I am at Mom's house, without the light turning on again.

Do you guys have any idea what could be amiss? I always appreciate your help! :)

Sounds exactly like my civic. I haven't gotten CEL's but I suspect my o2 sensor is going and that's why I can't get into lean burn anymore. Actually it pissed me off so much I pulled the insurance off that car and just have the Mustang insured and have been driving that. 1/8 Of a tank in 34 miles feels weird, but it's much more enjoyable to drive due to the car not pissing me off.

If you still have the codes posting them might be helpful for others trying to assist.

You have the information already. It is in the upstream O2 sensor circuit. Either a bad connection or the sensor itself. You were able to drive N miles without a light because it takes three failed cycles (starts) to trip the MIL for an O2 sensor.

From countless threads on EM, use only a Honda original sensor as ALL others have incompatible resistance or fail again too quickly. But before you drop the money on a new sensor, follow the service manual test procedure to look for a faulty connection.

Also heard of people having success with this o2 sensor. I believe this is the exact one, even same company and everything that the dealership sells. NGK is what's used for stock plugs and wires so, yea.

NGK 24300 Oxygen Sensor - NGK/NTK Packaging:Amazon:Automotive

The guy at O'Reilly did not tell me the code, just his interpretation. The Autozone guy gave me a printout and I will share that if I see it again, but it was definitely the downstream sensor, but the U-Fix It guy got upstream with one reader and nothing on the other. I have driven my car at least three times since.

One guy at Autozone said that you test O2 sensors with torches and digital multimeters. My torch is down in the valley and hopefully my meter is in my room somewhere.

Following the O'Reilly guy's false lead, I looked for fuse check lights, but did not see any sold separately. I thought that my digital multimeter would work, but I could not even remember its name, let alone find it. With everything else going on lately, I did not want to deal with that, so I mentioned it to a friend and took a nap. When I awoke, I tried to get her to tell me the name of the digital multimeter, but she just ranted about how she knew what a meter was and how to use one, she was an electric engineer.

"Okay, but what is it called?"
"Don't use a meter, just pull it out and look at it!"
"Right, but what type of meter is it?"
"I know what a meter is!"

She really did not seem to be paying attention. She called me, apparently angry about all of this. I thought that I found something relevant, but she was ranting and I needed to focus, so I asked her to stop giving me attitude so that I could read.

Three times.

Then I tried to tell her something about my car, but she started talking over me, so I asked her to stop.

Three times.

Then I told her she could argue with herself, I was getting off of the phone. Yes, three times.

She hung up on me.

Then she sent me several angry messages about how I disrespected her. Someone must have soaked her underwear in barracudas.

I will go and look for the code, but it contradicted the others.

Careful in assuming an O2 sensor fault code is actually a faulty O2 sensor. It may be, as they do have a "life", but other things can cause the O2 sensor codes to set.

Maybe check the basics, like 'plugs and leads, engine mech. condition (comp. test?), clean the IACV/throttle body, exh. leak ahead of the sensors, vacuum leaks in hoses and gaskets etc..

Oh bother! I found the code, but now I do not know where it is!

Ever since I replaced my oil pan, which required removing my exhaust manifold, I have heard a rattling when I accelerated. Someone told me that I had a cracked manifold and exhaust was hitting the heat shield, but I took it to a welding shop and the guy said that it was not cracked, although it was not square. One mechanic told me that he always had manifolds ground back to square while another said that bolting them down flattens them out. All of the bolts seem tight on the shield, but if there is a leak somewhere, could that cause a problem, or would it just cause another problem?

I was thinking you had an ultragauge, no?
Either way, I'd get the code next

I do not know how many of you read the thread where I replaced my friend's oil pan. If not, no worries, I am not linking it, please do not waste your time. If you did read it, well, all of us wasted our time.

At first it seemed like it was too bad that I had so many difficulties replacing my own pan, but I did it, and then I was able to help a friend! Then, while I was driving her around, she was able to diagnose my car by the sound!

She said that I had a vacuum leak. She still has all of my tools, so I was going to need to borrow or rent someone else's. I watched:
http://www.youtube.com/watch?v=9CPqbaSgcok and
http://www.youtube.com/watch?v=L788jKEVblY
However, I did not know where to check. Laugh if you will, but I do not even know which hoses are for vacuum, so I went to O'Reilly, where I found little help. I drove to U Fix It Automotive - Do It Yourself, and Do It Right!, and when the mechanic pulled my car in the bay, he explained how my AC was kicking on, and described the exact reason that I brought it in. While my last shop pulled vacuum and charged the AC, apparently they did not notice a bad valve, which he replaced, and then put in another several ounces of refrigerant. However, when he started my engine, the AC compressor still turned on and off, so he said that my expansion valve is bad, which is a 3-4 hour repair, and would cost $5-600 dollars.

Majestic has Valve Assy., Expansion (10n) (Fuji Koki America) for $54.53 Honda Automotive Parts
They said that would need to be replaced as part of a kit. What else needs to be replaced?

My repair manual intentionally omits AC service. The service manual seems to skip the expansion valve. I am not finding very clear instructions anywhere for my car. So far, the best that I can find is http://www.youtube.com/watch?v=RkKry31lk1Ewhich is for a Camry!

U-Fix it will evacuate the system and then recharge it afterward.

Then I need to replace my timing belt in a few thousand miles!

By the way, this had great information! Summer A/C Guide, How it Works, and When it Doesn't - Honda-Tech

Finally, while I was there, I decided to replace my rear brake cylinders, which leaked. The mechanic started telling me how to do it, but just took over, and I learned once again not to eat Super Nachos, especially with a pint of hot sauce, and then walk 1.9 miles in twenty-five minutes.

Man with all the money you have been spending on repairs you could have bought an ok condition insight like I did. I got tired of fixing the Black Mamba's problems.

Oil pan: $85
Alternator: $142
Replacement visor: $75
Replacement dome light lens: $6.11
Door lock: $85
Purge and recharge AC: $100
Fix AC leak, top off AC, and replace brake cylinders: $139.26

Anything else? That totals $659.58 and I have had the car eleven months.

Thats not too bad, $59 a month , thats some cheap car payments. Plus you might be over the hump of repairs where none might not be needed for a while. When I work on car like that I chalk it up to education, exercise, hobby, and gaining a practical skill that might can help others or myself in the future.

I accept responsibility for all of the AC work, we will just classify that as education. The problem is that it is still not working right, and it keeps turning on and off when I am idling, which is why the mechanic said that I need to replace the expansion valve. I understand that when you do that, you also need to replace another component or two, and had read that you should replace all of that any time that you have a leak in the system.

So, unfortunately, I am not over the hump yet, need to replace the timing belt in 3,500 miles.

I went thru something similar with my car but it was just when starting it would it die. I cleaned the MAF, throttle body, pcv, egr, replaced all the vacuum hoses, cleaned iac, went thru procedures to setting timing and idle. Now it is pretty much fixed only does it every once in a while, but at least it only does when starting and not running. Luckily I found message board articles doing a run down of fixing issues with my particular car. Maybe you do the same with your car? Not familiar with your type of car sorry, but the in general things I listed may help, I know mine was a combination of things.

One trick I do know that I have used in the past(wastes a little gas if you idle alot) is set the idle higher where it might not die when you drive it, then when you have more time to work on it lower it again, try a fix if it works you are done, if not set the idle higher so you can drive it without dying then next pay day try another fix, if that works your done, etc. Might get you by until a permanent fix, kinda a work around.

At stops, I use the accelerator to idle higher. I have not been driving much lately, although I had been driving without air conditioning even when it was well over a hundred degrees, but I always use it if I have passengers.

My first car a 1978 Datsun B210 I had to do that with. I was 16 and knew nothing about cars so sold it, regret that I should have tried to fix it and learn something.

Maybe with it setting it the gas has gummed something up in the fuel system, have you tried running a bottle of techron thru it?

Why don't I just fill up at Chevron? :)

I put a bottle of seaforium into the gas tank a few months ago, my car was idling rough, and I believe that I had a CEL for engine misfire, but I used my Ultragauge, which I keep in the Forester, which had those exact codes after Pep Boys replaced my timing belt incorrectly.

Somehow, my Civic keeps having the same issues that my Forester did.

My Sergeant was a certified mechanic, but said that he did not enjoy working on other people's cars, so he changed careers, at least twice now.

I have not noticed any improvement after filling up at Chevron.

So the check engine light is caused by the ac cycling?

I honestly do not know, once we turned it off, it did not come back.

One shop said that I had a bad AC compressor and another said that I may, but the expansion valve was bad, and I needed to replace everything together. The lowest estimate that I can find is over a thousand, but the mechanic today told me that I can do it myself, eventually.

Hanynes has or had an Automotive Heating & Air Conditioning Techbook. It might be of some help. Covered maintance, troubleshooting and repair.

How does the ac perform otherwise? Techs give you any specific info?

I almost never use my air conditioning, even though I drive a black car in Arizona and have a professional job.

I just rarely have passengers.

My air conditioning works pretty well, although there are some sounds that apparently come from the bad expansion valve.