JohnnyRed

I've been doing a TON of searching and have some ideas but am looking for some insight

2005 TSX 6spd
155k miles
Basically Stock
No CEL
No Flashing VSA
One code for a Brake petal switch


Here's what's happening:
While accelerating between ~2500 and 3500 RPM in a higher gear (4th, 5th, 6th) I feel the car stutter slightly. Sometimes it's worse like the VSA is engaged, sometimes it's not bad. It's very similar to what someone described in an APP thread where they mentioned "it felt like the car was getting jerked/pulled with an invisible rope". It happens at light throttle but most often when it's close to WOT ~3k rpm.


I stopped by the auto parts store yesterday and they pulled 1 code for a brake switch. I just found this thread Post #9 which makes it sound related.

I bought a used APP sensor for cheap that was newer than mine, but it didn't seem to do much/anything. So, I took it apart to see how it works. It appears I may be able to clean the sensor, not sure if that has been tried before....


Here are my thoughts:

• Bad brake petal switch (Maybe? lights work, see linked thread...)
• I have 2 bad APP sensors (Maybe?)
• Fuel filter clogged (Maybe?)
• Injectors clogged (Maybe?)
• Broken engine mount (Maybe? There's no oil or cracks...looks dry and flaky)
• Vacuum Leak causing hydraulic engine mounts to not function (Maybe?)
• IAT sensor going bad (Doesn't seem to be temperature dependent)
• EGR Valve/Sensor (Who knows.....)

Less likely things....

• Bad O2 Sensor causing lean/rich
• Clutch slipping (it chatters when cold but RPMs don't climb)
• Plugs (They look used but OK)
• Coil (Probably not....no code)

Any thoughts? Anyone have any similar issues? I'd hate to start replacing things somewhat blindly. Thanks!

TexasHonda

Thread you referenced suggests that brake light switch may affect performance. Long shot, but CEL needs to be resolved and you never know.

good luck

JohnnyRed

I replaced the brake switch the same day because it was only $6. I also ran a bottle of Techron through it.

It seems to be slightly better....but It's tough to say. I still feel the unevenness & jerkyness around 3100 rpm. It doesn't seem to be dependent on the throttle position, but it almost always happens around the same RPM.

To me that seems to point toward something that happens regardless of speed or throttle position. Perhaps fuel, Vacuum engine mount, EGR, or something else....

TexasHonda

If you have a scanner w/ data monitoring capability, check the Long Term Fuel Trim (LTFT). This may be trending high or low, but not enough to trigger a code. If you monitor while driving see where LTFT is going when symptoms arise.

good luck

JohnnyRed

Technology has gone a long way since I was modding my first 94 ls/vtec....

It looks like they sell bluetooth OBDII scanners & there's the torque app.

From my small amount of research it appears Torque Pro app should datalog and judging from the Amazon reviews this OBDII will work with it:

https://play.google.com/store/apps/d...l.torque&hl=en

Any experience or recommendations on what to look for? I'm guessing EGR voltage, Fuel Trim, Intake air temp, Throttle position.....There's probably more.

I had it happen today from 2500-3000 rpm just barely hitting the gas. So, I guess slipping clutch is out.

It seems to be most frequent shortly after engine startup.

JohnnyRed

Well I got "Torque" and a logger. The logging is a bit slow. About a point every second. It makes it a challenge to pick anything up.

It's official. I have no idea what I'm looking for. :-)

It happened yesterday when I was on the expressway. The "Vacuum gauge" seems to drop right as it's happening. The O2 sensor voltage drops. So does the Short Term Fuel Trim.

I think that means it's running a little lean. The Throttle position doesn't really change, so I'm guessing I'm feeling it go lean (or maybe rich if I'm reading it backwards). But I don't know what's causing it. Vacuum leak? Fuel Presure drop? EGR? Temperature Sensor? Still unsure.

It seems like it may only do it when the air intake temp is blow 80*. If I sit in traffic and then accelerate it doesn't seem to do it (need to test more when the intake temp is ~100.