bc77711

So, I have a 2010 Honda Civic EX-L with 84,000 miles on it. I have noticed a "rich" smell from the exhaust a few different times while idling and on the road. It's not consistent and sometimes it doesn't have a smell at all but the biggest difference I've noticed is my MPG has gone from around 26-29 down to an average of about 24. It doesn't smell "sweet" like coolant. I've noticed an intermittent decrease in power as well but it is very subtle.

The check engine light is off. The problem has been going on for a few months. For maintenance and a possible fix to my problem, I replaced the plugs and added Seafoam to the fuel. This was done a couple of months ago. I'm just not sure what the problem is and hoping someone here can help. I've been thinking it might be the cat. converter but there's no check engine light and when I pulled up the live data, the converter was pushing around 1000 degrees Fahrenheit which from what I read is normal.

Any replies would be greatly appreciated!

DaveSi677

Pull the spark plugs and look at the state of them...

Here is a good reference:
NGK Spark Plugs USA

How does the car perform apart from that like acceleration?

97emsedan

And check your air filter while you're at it...

tamboo

tested your plug wires lately?
if any are over 25k ohms = replace
that was my rich smell issue.
why cant anyone make 100k mile wires???:hmmm:

vtecnique69

i dont think he has plug wires.

Yogster

check the o2 sensor also. typically when they go bad it dumps more fuel instead of making the car run lean ( kinda like a limp mode) sometimes it does not show up on a scan or a check engine light but that's a typical gremlin for a Honda

DaveSi677

o2 sensor if faulty should trigger a code/check engine unless he has other issues with the car that we aren't aware of.