I am currently running rich, and I tackled my CELs first. It was running rich and was getting p420. Using an infrared thermometer, and it was 100 degrees hotter going in to the Catalytic converter, than going out. This proved the catalytic converter was not working as it should. I replaced cat this week. Upon removal, the cat was internally destroyed, even the O2 sensor was broken. There was a noticeable performance improvement, which I originally thought was a slipping transmission on my 219,000 mile 1997 Honda Accord LX(automatic, stock). Now seems to shift better. I checked for exhaust leaks after replacing the Cat, it looks great.

Seems better, but theres still a problem. It's still running rich. Not as rich as it was before the new Cat was installed, but it's still rich. The CEL is gone now, and exhaust rattles now, but not the reason why it's running rich...

After warming up, the car likes to sit at about 800-850 RPMS. Normally, I believe the car should be at 650-700RPMS. I'd love to know where to look next, or what could be causing a rich condition.


I would love to know what needs to be looked at there. There isn't a whole lot on Hondas running rich. I will say, the car seems to idle fine. No surging or rough idle.

I've checked all the basics. Air filter and spark plugs are new. Wires aren't too old, (i think, may have been replaced at 100K) but are factory wires, do not appear to have any issues. I swapped a new set of wires on, just to confirm and the issue hasn't changed. The fuel filter is old, I will be replacing that soon. New cap and rotor will be ordered soon too. Coolant has been bleed and filled to spec, to ensure there is no air in the coolant.

What do you guys think? What am I missing? Where should I look next? I'm not interested in throwing parts at it without a good logical reason.

 

The primary O2 sensor is a possible suspect contributing to the running rich condition.

 

I should have mentioned that in the first post. I replaced both 02 sensors at the same time. Issue still remains. Thanks for the suggestion though.

 

Do you have a scanner that can read the fuel trims?

Have you tested the injectors to be sure one is not leaking.

Can we assume this is a stock set up on the car.

 

Poorman. I have a cheap scanner, it doesn't read fuel trims. Just CELs.

I have not tested the injectors. Would a leaking injector cause the idle to be higher and run rich? Every once in a while I swear I can smell fuel in the engine bay, but I don't see anything leaking, and I'm in a garage where chemicals are abound.

Yes, the car is completely stock. This is my daily driver. I try to keep it as original as possible. I'm more of a, I want save money and not have a $350 car payment, and bank that money towards buying a house with a nice garage where I can work a nicer car one day in the future, kinda guy. I'm hoping to get another 100k miles out of this accord.

 

Well, you have no codes yet say the car is running rich. So we are going on "smell". I asked about "mod's" as there have been reports of hot air intakes causing a rich running situation - can't verify but what I have read.

The idle, well that can be a number of things.....usually a good cleaning of the IACV and the TB will take care of that - assuming someone hasn't messed with the idle screw (last resort IMO) or the throttle cable (too tight holding the butteryfly open a slight bit).

I only went with a leaking injector for the reason of either too much fuel, which with injection and computers is kind of hard to do, or lack of full combustion.

I wish I had a better answer for you. Solving a "no code" yet running "rich" is not that easy. I'm more trying to give you things to think about or test that might lead to a solution.

 

Remove the snorkel to the throttle body. When the engine is at operating temperature with a stable idle, cover the lower port on the throttle body with your finger. Does the idle return to normal?

 

Thanks Poorman, I appreciate it. I have a stock airbox with a stock air filter. No rich CEL codes, and it is strictly from smelling it in the exhaust.

I haven't really messed with the throttle cable. I'll take a look at it to make sure it's not catching on anything. I've never messed with the idle screw, and at your suggestion, I'll avoid that. I have been wanting to clean the throttle body, so I may grab some carb cleaner and give that and the IACV a shot today.

I'll take a look at the injectors too to see if there is any leaking there.

 

So it sounds like you may have messed with the throttle cable in the past which is no big deal as long as there is around 8mm deflection when it is slack. The other thing that you can try is using throttle body cleaner clean the exterior pulleys at the body where the throttle and cruise cables connect. Once clean you can lubricate with ATF.

Do not use carb cleaner when cleaning the throttle body/IACV if the car is running! Use a cleaner that is for a throttle body as you run the risk of ruining the cat converter if you use carb cleaner. If the engine is off you can use most cleaners as long as you just let it dry for a few before reinstalling the intake hose. Note for those reading the previous is not true for cleaning MAFS.

As far as running rich goes I would be listening to each injector for proper clicking. If one injector sounds quite then I would suspect an injector is sticking. As far as cleaning injectors goes there are plenty of products out there from direct injector treatments to fuel tank treatments. Obviously the fuel tank treatments are the easiest way to go. If you can find some BG 44k add that to your car when it is around 1/4 tank or simply get a couple bottles of Chevron Tech and do the same. Either way add the injector treatment when the fuel tank is low and then drive the car until the car is near EMPTY before filling up. The more potent the better.

It could also be that the injector resistor is failing or has failed. Good luck!

 

never heard of a honda running rich with out a check engine light...if smell is all your going on,,,,have you pulled the new plugs to read them??? i would also look into replacing the muffler if the cat was bad,,,good luck