My 00 Accord has about 110k on it now, and I've noticed the gas mileage has dropped pretty significantly in the last 10k miles or so. From an average of 30mpg to 26-27mpg.

I've tried driving slower, going easier on the throttle, raising tire pressure, changing oil, etc. to no avail.

I also had my timing belt/wp, etc all replaced, and I thought the clattering I've been hearing was my valves.
I asked the mechanic, and he said, not my valves, but my injectors.


I was wondering if my injectors may need to be pulled and (sent in to be) cleaned. Maybe they're gummed up and have a poor spray pattern, causing poor mpg?

What do you guys think?

 

Search for threads about poor gas mileage, it's been covered a thousand times.

 

I am very ignorant when it comes to cars but why would fuel injectors make a clattering noise?

Try some of that fuel injector cleaner, before you pay the mechanic to clean them.

 

I searched, and I've already done most all the basic stuff.
Replaced plugs, cap, rotor, oil change, seafoam.
Although, I admit it's been a while since I changed my air filter.

There are a lot of references to the O2 sensor, but that should throw a CEL if it goes out, right?

But anyway, my question was pertaining more to the injectors.
Would they be the source of the ticking/clattering, and would a good cleaning them clear that up as well as affect gas mileage?

 

The ticking/clattering you're hearing is the relays for the injectors.

The relays are there to time when the injectors should fire fuel into the cylinder. It helps to increase horsepower by delaying the timing under heavy load and other things.


Bottom line, it's the relays clicking to make the injectors fire.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Obsidian &raquo;</TD></TR><TR><TD CLASS="quote">The ticking/clattering you're hearing is the relays for the injectors.

The relays are there to time when the injectors should fire fuel into the cylinder. It helps to increase horsepower by delaying the timing under heavy load and other things.


Bottom line, it's the relays clicking to make the injectors fire.</TD></TR></TABLE>

Not really. The ECU completes the electrical path to ground for each injector, the duration of which is determined by a number of factors. The "click" noise is from the injector itself, or in more detail, the pintle (sp) that is pulled up when the internal coil of the injector is energized.

"""There are a lot of references to the O2 sensor, but that should throw a CEL if it goes out, right? """

Not all the time. An O2 sensor can get slow and lazy, decreasing your fuel mileage, but still provide enough activity to keep the ECU happy. Try this test...
With the engine thoroughly warmed to operating temperature, try to hold a steady RPM in neutral of about 2500 for about 30 seconds. If the RPM varies by itself by about 50RPM every second or two, that would point towards a lazy O2 sensor in my experience.

 

Then why is it on engines that use cam lobes or such to fire the injectors, you don't hear this.

I'm just curious. I always thought it was the injector relays.

 

try changing your pcv valve, if that doesnt work, try using gumout fuel system cleaner, thats worked better for my fuel system than anything. it cleans your injectors, valves, and pistons. if all else fails, try cleaning your throttle body. it could be a whole bunch of things