Gas smell after exhaust mod

I'm having the same issue I read about in regards to changing the stock exhaust to a Coffman exhaust and now I smell gas when I've stopped at a red light and when I pull in to my garage. My mpg how gone way down as well. I took it to a regular mechanic but they had no clue as to what resetting the ecm/pcm was. Are Honda mechanics the only ones who can reset the ecm/pcm? Any help would be appreciated.

Bertmcgert said:

I'm having the same issue I read about in regards to changing the stock exhaust to a Coffman exhaust and now I smell gas when I've stopped at a red light and when I pull in to my garage. My mpg how gone way down as well. I took it to a regular mechanic but they had no clue as to what resetting the ecm/pcm was. Are Honda mechanics the only ones who can reset the ecm/pcm? Any help would be appreciated.

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You can get the reset done by removing the battery cables, wait 20 mins then hook them back up. The bike will reset it-shelf. Just note that you will lose the settings for the DCT (if you have one) and the bike will have to re-learn when to swift. Make sure to use reg gas. If you need help I am a nice 60 miles north of you if you want to ride up here.

What mjc said does work.
However, after reconnecting the battery, let the bike idle till the fan comes on-then ride and let the ecm do its relearning.
Plan on a nice ride-an hour is good - and not just at a steady speed.
I had the same issues when I put on a Muzzi exhaust, then stock, then a Radiant, then stock, then the Muzzi again and now back to stock.
I just confused the heck out of the ecu. Got mine reflashed at the dealer (no charge cuz they like me) and a nice chat with the tech was where I got the disconnect/reconnect info.
A reflash is the best way though, only takes a half hour or so.

Oh, and this is your first post-so Welcome!!!!

Thank you guys for replying. I actually tried twice disconnecting of the battery after reading previous posts on this and the other forum (fyi I like this forum better). The only thing I didn't do was go on an hour long ride. I'll give that a try this weekend. Hopefully it'll work. I took half the day off since it was nice out and picked up my CTX from the mechanic I took it to. It's really hard to find a good mechanic in NYC, I had the chain lubed and adjusted, came home to check the work and the lock nuts were coming off and were not tighten to specs. Know any good Honda mechanics outside of NYC?

I took it on a ride and continued to notice the gas smell. I've only been using 87 gas and tried different brands. I only got 85 miles to my last tank of gas before the blinking bar. So I'm hoping it's the ecm reset. If not I'll to start looking for different cause. I did smell it on the right side under the right side shelter. But no visible signs of a leak. Again thank you guys for your help.

my guess, based on my very similar (near exact) experience is that the O 2 sensor is screwed up.
If it's under warranty, put the stock muffler back on (which you never removed anyway) and get to a dealer for a diagnostic check.
And reflash the ecm, The home fix may not work if the O 2 sensor is trashed.
I say warranty because the sensor is pricey. They will not have one in stock, I'm sure.
If you try the battery thing, remember to let it idle till the fan comes on=then a nice long ride at varying engine speeds and loads-i.e.. normal riding.
Keep us posted.

I agree with ofdave there's something seriously wrong and your 85 miles per tank is screaming out loud to you "take me to a dealer". No wonder you smell gas... you should be getting 170 miles! It doesn't seem logical for the ECM to have that large span of control without something really wrong... IMHO.

I think we'd all be interested what the final outcome was?

Bert, In my opinion, if you smell gas and only get 87 miles out of a tank of gas, you have a major gas leak somewhere. Of course I am not on site, but smelling gas is a danger warning. Also, you didn't indicate that the bike ran very poorly which it would if it were an engine or computer problem. I would look closely at my gas lines from the tank to the fuel injectors and I will bet you find a leak. Good luck and stay safe.

I'm going to inspect the gas lines on the bike tomorrow. I'm probably going to take it to a dealer outside of NYC. I forgot to mention that I had a radiant exhaust, too loud but still smelled gas and now have a Coffman. It doesn't seem to be running poorly but doesn't have that pep it once had. I do get a lot of gurgling sound when decelerating. I'll keep you guys posted.

My guess is that 5-10 min. after you stop in your garage you no longer smell gas. If there were a leak you should still smell it.
Try turning on the key without starting the engine. Our CTXes are fuel injected so there is no gravity gas flow. It flows because the fuel pump pushes it. After the key has been on the fuel pump (sometimes you can hear it pressurize just before you start) will pressurize the system. If you have a leak in a fuel line you will notice it then as fuel is being pumped and you should really smell gas. If you don't smell gas at that time, there likely is no leak.
Have the dealer do a diagnostic check-same connection for the ecu reflash-and see what shows up.
It should take no more than an hour. No panels come off, just the seat.
Remember to let the bike idle till the fan comes on after the reflash. The dealer should know that but may need reminding.
I am still of the opinion that will fix your problem unless the diagnostic check shows the 0 2 sensor to be bad.
Put the stock muffler back on before you go to the dealer-and leave it on if the reflash solves the problem.
Low back pressure being sensed from the non-stock mufflers causes the ecu to dump more fuel giving you your gas smell.
Let us know the results of all this. Good luck.

I'm still with ofdave. But just for the halibut remove the sparkplugs in the morning before you start the bike. If they're black you've got a problem in the ECM / O2 sensor fuel control circuit. Sparkplug Check Here.

I've only put 1000 miles on the bike since I purchased with 600 miles on it. I checked both spark plugs. The right side seemed fine, the left looked a bit rich. I reset and took it on a ride. I didn't smell any gas let's see how this holds up. Thanks for posting the details on the reset burdicda.

"Stump the Chumps" (from Car Talk on NPR)

Did you ever take the bike to a Honda dealer? I am hoping for a definitive answer to why you smelled gas and only got 40 something MPG. I can't see that one spark plug being the problem, but it wouldn't be the first time I have been wrong.

I too am interested in a follow up.
What has been done and is it fixed?
What did the dealer find?
Curious minds want to know.

Put me on the curious list also. That one plug sure looks like too much fuel was getting into the cylinder. And the dealer found?

Merlin III said:

"Stump the Chumps" (from Car Talk on NPR)

Did you ever take the bike to a Honda dealer? I am hoping for a definitive answer to why you smelled gas and only got 40 something MPG. I can't see that one spark plug being the problem, but it wouldn't be the first time I have been wrong.

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I should have added that all this time the bike ran pretty well? I filled my bike up today up today, when I wondered that since the poster was new to the bike and didn't have a manual (I think), was he overfilling the tank? That may partially explain the low MPG and would certainly explain the gas smell?

I overfill my tank as a norm all the time. I fill it to the gas cap neck. No gas smell or low MPG. There's still that dirty spark plug that looks like its been running too rich. Even if all is well I'd remove that plug clean it all up and run it 50 miles and pull it out to examine it. SOMETHING caused it.

I'd suspect plug, wire or coil. Plug not firing correctly for any reason can make it look like that and cause poor mpg. Also check the two wires connecting to the coil for good connection.

Yes Randy and Novac, but the poster said that the bike ran well. If it wasn't firing or firing consistently, there would be a performance problem. You wuld know it right off. As per over filling, I'll have to check, but I believe that was discussed on the other forum and it was an issue. Quite possibly, there is no one reason, but multiple reasons?

Sorry I haven't posted sooner. I haven't taken it to the dealer yet because I'm trying to find one outside of New York City I can trust. What I've done to try and figure this out is cleaned the plugs and flashed the ECM/PCM. Filled up and have been riding to work like normal for a week. I didn't smell gas and got 100 miles since I had to refill the tank. Today I was riding in the D mode and smelled the gas again. No visible leaks, and is running alright. Just not making any sense of this. I've also purchased a diagnostic tool to look even further into the issue, will receive it next week. If I can't figure it out I will take it in before the season is over. I definitely keep you guys posted on the progress.

Did you check your valve adjustment?