I have an 05 TSX 6mt, roughly 70k miles. Over the past few months I have had this surging sensation coming form the car whenever I try to maintain a cruising speed (cruise control off). It's gotten worse and now my MPG has taken a dive. It's hard to explain but if I'm going seventy on the freeway and have found the sweet spot in the accelerator pedal (holding my foot still) the car will surge back and forth slightly. Its almost like the bucking sensation you get in a manual trans when lugging the engine only it's less noticeable.

After playing with it I came up with a few more hints:

-Gas mileage has decreased
-Occurs in any gear with the ac on or off, just as long as i'm holding a speed.
-issue doesn't occur under hard acceleration or braking.
-issue does occur when only accelerating slightly (not giving a lot of gas but some)
-The throttle lags when you first give it gas.

I'm thinking it's either a sensor going out or one that needs cleaning. (MAP?, O2?, IAT?)
I'm going to clean my air filter right now but I don't think that will fix it.

I've already ruled out gas quality as the issue as I've been through a few tanks and yes I use premium.

Thanks in advance!

 

So after doing some google searching I'm lead to believe that its the APP sensor going bad. My CEL light isn't on though. Could it be going out without flagging the computer?

 

Failing primary O2 sensor (mixed air / fuel sensor) can do those symptoms too.

 

Try to notice whether RPM is going up/down 200-400 rpms when this happens.

If yes, then lock-up torque converter is "hunting" on/off. It could be a bad LU solenoid, however this would set a specific fault code. A hydraulic fault may cause this problem also, but again should set a code indicating the LU torque converter is not locking.

good luck

 

Yep.. def sounds like the APP sensor.. I just went through this issue and mine never triggered the CEL or any other warnings.

I had the exact same problem you did.. i was able to find a used APP sensor from a scrap yard.. it's an easy fix

after i replaced it, problem solved. no more "surging"/"lagging"

do a search on here for APP Sensor and you will find several other posts (some by me) regarding this issue.

good luck and let me know if you need any help.