Tire are not the problem...sticker is a relative term and have probably less than a 5% mpg inpact, even with the thin, green carbon heavy tires.

OK, emissions within standards...

Tires properly inflated...

Added drag impact not a factor...

Cats clear...

No codes...

1) Air intake and filter box checked through entire length for obstructions, objects or leaks? Especially between air flow sensor and intake?

2) Sounds like too much fuel is being injected, perhaps a problem with the anti-knock sensor? If it's retarding the ignition to avoid pre-detonation the fuel burn would be less efficent and cause your mileage to drop. That would also be a side effect (pre-ignition, that is) of carbon build-up. So what fuel are you using? What octane level? Have you changed stations around the time of the drop?

Dude, I understand how frustrated you must be, but this is really weird.

 

DuckDodgers, I cannot explain to you how much I appreciate your advice on this.

1. Air intake i think is clean. When problem first reared it ugly head, i took the filter out and cleaned and re-greased (KN Filter in Icebox with trim mod to create perfect seal).

2. I'm not too keen on where the knock sensor is or how that can malfunction. I've been rotating between my are 4-5 gas stations which are only Exxon, Mobil, and Shell. We get 93 in NY for premium gas and I have never put in anything lower in my car. I've never even used any gas that wasn't Exxon, Mobil, or Shell in the car.

3. They also replaced the brake pads recently and doesn't seem to be anything sticking or rubbing up against the rotors.

4. I've ran 2 bottles of Techron concentrate through the gas tanks within the last 10 tanks. I've also ran sea-foam twice through the brake booster line and flushed out some of the carbon build up. Second time resulted in a back-fire.

I'm starting to suspect that fuel is just leaking into the engine somewhere or is being burned late. Could that explain why running the engine harder has less impact on mpg when compared to running the engine conservatively. Right now, if i run spirited and just flop about my MPG averages 18 MPG. If i drive gas consciously, i'm lucky to get 20 MPG. Feels like when running hard, doesn't matter since that much fuel is suppose to be consumed but when driving less aggressive the car is leaking too much gas for the amount of air given at lower RPM's.

 

OK, so perhaps we've got an injector problem. Have you had any long start issues? Maybe an injector or two are leaking (which means they leak down while stopped and need a couple of seconds to refill and then have the cylinder fire) or clogged and spraying a poor mixture. If the injectors were hanging, we'd expect a code and if they were too far off a fouled sensor.

I'm gonna say pull a plug or two and inspect. If they look normal, then other than a fuel leak/injector problem, I'm really outta ideas.

A set of injectors can be had for about $150 plus a core charge...or you can have a company clean them for about $100. The fuel injector cleaning solutions they run through them won't solve this problem, as it might be actual clogging of the filter internal to the injector by particulate materials.

 

Hrm...I can't seem to find TSX fuel injectors online anywhere. I'm guessing its a part not normally replaced? Any other ways to check if the fuel injectors are messed up?

 

I found the injectors easily. Also would need a couple of new "quick connect" fittings that must be replaced after each use.

http://www.injectorwarehouse.com/inj...ura/mp4181.htm (as an example)

Honestly though, at this point, rather than throwing parts at it, I'd look for an Acura specialist.

I found these guys via a search...don't know how good they are, but you can call them and ask?

http://www.qvdautomotive.com/New-Yor...to-Repair.html

or here's another:

http://appleautoandtruckcare.com/veh...asp?make=Acura

Note that I don't know these guys, but calling and talking might get you an idea of if you would be happy with them taking a look.

 

I took it to my dealer and gave them a break-down of the issues. They're pretty good with diagnostics in the past, but i'll check a local shop perhaps for more answers.

Those injectors aren't OEM i assume?

 

Didn't specify, but I expect not. Just showing we have options all over.

Acura pricing is about 160 each for the assembly.

http://estore.honda.com/acura/parts/...310&dl=251416#

 

Jezzz....$160 is ridiculous. I wonder if there's a way to diagnose a broker fuel injector..

 

Should I be cynical and say the usual indication of a defective or clogged fuel injector is a reduction in MPG? The TL's were having a problem with blockage of the air intake at the front of the car, by the resonator. You have confirmed the entire intake is clear and unobstructed, right?

 

I'm going to check in the air snorkel this weekend...I hope I don't find a dead bird or anything in there. But other than that, the rest of the intake is clear.

 

Woulda been the first thing I'd have done. Plan on doing mine here ASAP at round 60k mileage. Anyways, been a few months, did you ever get to the root of the cause? Were coils ever looked at also?

 

mlittleton, you are aware that the TSX doesn't have a "normally" serviceable fuel filter, right?

 

Haha actually I wasn't. That really surprises me though. Every car I've ever had has had a replaceable fuel filter.

 

Holy thread revival. Just to update everyone - my situation got a little better but its still terrible. My average now is around 19-20; not quite as bad as 18 but still nothing like the 25+ I used to get. And I'm driving very cautiously.

Some things that helped it and some things I think might be the root cause of it.

I had the cat looked at, nothing its all good. Spark plugs still look good so it doesn't seem to be a fuel thing.

I over-inflated my tires to about 34 PSI front and 32 PSI back and it seemed to help the mpg somewhat. But with over-psi you tend to lose that added air rather quickly so it comes back out of your pocket when you put another $1.50 into the air pump at the station.

My rotors/suspension seem a bit off. I had the car aligned and the wheels balanced so that didn't seem to be an issue, but stopping and riding over bumps i'm beginning to feel a wobble and brake pedal travel that seems excessive. Anytime parts have wiggle room means energy to absorb; which in turns means added energy to keep moving. My next steps would be to replace my rotors and check the suspension. I'll likely check the brakes at that time to make sure nothing is clogged in there as well.

The tires I'm using are Pole Positions which are heavier than OEM and have a special 2nd layer compound which is stickier as it wears out to compensate for less thread. While it's safe, i think it may cause the tires to have very free rolling resistance. I'm switching them to lighter tires at the end of the summer to see if that makes a difference.

 

You might check the fuel injector/fuel rail connections for leaks. I had an injector leak badly after reinstalling injector to rail on a 94 Accord. Oring problem might happen spontaneously. I found all the orings cracked/dry.

This problem is costing several gallons per fillup. At that rate, you could pay for some professsional help.

good luck