I have a 2006 LX 4cyl with 280,000 miles. Over the past 10-20k miles I have noticed a dramatic loss of power and gas mileage in city driving. City mileage has dropped to about 15mpg. The mileage on the freeway remains good.
The loss of power is most noticeable when accelerating from a complete stop. The car has no "pep".
Any ideas would be appreciated..

Thank you

 

Even though I'm not a fan of "thowing parts at a problem," under the assumption you're getting no codes, I might be inclined to swap out the upstream O2 sensor.

 

That is correct. The car is not displaying any codes.
I also forgot to mention, because I believe it to be a unrelated problem.

Every once in a while while driving my radio will shut on for a couple of seconds and ALL the lights on my dash will flash on for a few seconds ( door signals, check engine light, battery light etc) . During this time it feels that the car bucks a little if the gas pedal is pushed.

 

On numerous occasions now I've suggested a new O2 sensor to folks complaining of poor fuel economy, and in many of those cases, the new sensor has put things right, even though no codes were being thrown.

On the electrical issues, I'll have to defer to others more knowledgeable.

 

For all systems to go dark, there must be a temporary open in power supply; battery, battery wires, main bus, ignition switch or connections between these elements.

Some possibilities are cracked battery post, loose battery connection (+ or -), connection to main power bus, loose fuse connection (100A or 50A fuses).

It is also possible that a faulty ignition switch could cause this problem. It is unusual for total on/off problem w/ ignition switch but over the years the ignition switch has been frequent cause of no-start due to intermittent connection in the electrical key switch assy.

An intermittent problem is inherently difficult to locate since most of the time, problem is not presented. You will need to investigate the possibilities looking for damage or looseness. Ignition switch can sometime disclose a problem by wiggling the switch to simulate vibration.

good luck

good luck

 

Thanks for the ideas TexasHonda.

I tried jiggling the key while the car was on and nothing happened.
I cleaned the terminals. We will how that works. There was some corrosion under the clamp.
I will attempt to check the main power bus later tonight.

I have searched this forum as well as the web and have seen a lot of posts stating a similar problem happening with the lights flashing and radio going out for a couple of seconds. Many of the posts lean toward a problem with the voltage regulator in the alternator.
Is this possible? I checked the idle voltage at the battery with no accessories on, and it measured 13.8 volts. I again measured it with the AC on and measured 13.72 volts.
If this could be part of the problem, and since this is not happening all of the time how can I get an make sure that the alternator is ok?

 

Alternator seems to be working fine. Only a dead short would bring voltage down enough to shut down that many circuits. If that happened some fuses would blow for sure or something would burn.

good luck

 

And I know I'm coming in way late but check the "other" ends of the cables.

There are some pretty cheap voltage readers that plug into the cig lighter socket that will monitor the voltage while driving.....car acts up, a quick look at the reading on it might tell you something.

 

Thanks to everyone for the help.
I am not sure what the solution to the problem was but it seems to be fixed.....
I did the following and the problem has not returned for a couple of days no.
Cleaned cables and connections
Tightened / checked connections including grounds around fuse box and ECM.

If the problem returns I will post..
Thanks again

 

Fingers crossed........thanks for the follow up.