Hello all,

I am new to this forum, but I'm looking for some help and who knows, help someone else with this issue.
I have a 2009 Acura TSX, 2.4L manual

When I bought the car it felt very quick: torqey in low RPM, fast in high RPM, never lacking power.
After a couple months the car started to feel more sluggish. It varies almost completely randomly though it gets worse when driving long distances.
Also when it's hot it tends to be somewhat worse, and it gets a little better when I turn the AC off.
But the problem is never entirely gone, and I've never been able to isolate the issue.
There is an accompanying slight rattle when accelerating (the harder I accelerate, the more prominent the rattle).

This issue has been going on for over a year.
I have tried many things so far, the issue is driving me nuts because it completely sucks the joy out of this car. Never mind that it takes me from A to B just fine.
I have a number of friends/relatives who are experienced mechanics, but none of them so far have been able to diagnose it.

Here is what I have tried so far:
- Timing chain and tensioner replaced (yes it was stretched, and yes it improved the performance somewhat)
- Spark plugs and coils replaced (useless exercise, all of them were still in good condition anyway, no change)
- Replaced the filter with a K&N performance filter and cleaned the air intake sensor (thinking it was an air inflow issue, but no changes)
- Refreshed transmission fluid with AC Delco's synchromesh friction modified (this solved the accompanying "shudder" at 20-30Mph, but the main issue remains)That's pretty much it. The rattle is still there, it's still slow.


Clutch: The Acura dealer told me that the clutch needs replaced, but every mechanic has told me for every manual car I owned that the clutch needs to be replaced.
The clutch feels fine, there is no slipping, I tested it multiple times.

Anyone who can figure this one out will be considered very smart and experienced.

 

Anyone put a good scan tool on it to check for knock and misfires?

 

It has been scanned multiple times with various scanners, nothing comes up. The issue does not occur when idling / not driving.
There are no warning lights on either.

 

Well I do know on the 04-08 TSX & the 04-08 TL the APP (accelerator pedal position) sensor is a somewhat common issue, which can sometimes be accompanied by a VSA warning light. It will cause the car to act randomly with what seems like power loss, etc... Usually it can be temporarily fixed by turning off the car and restarting it. Not saying that is the issue here, but its something to consider and can easily be mistaken for another problem. It can cause the car to not go over a certain speed or rpm as well or just make it feel like it takes forever to get up to speed.

When you say that it feels more sluggish, is it like you got WOT and the car barely climbs in RPMs & speed or something else?

 

Thanks for the suggestion, I'll look into that!

It is sluggish in that it feels like it is lacking torque in low RPM. Once it is up to high RPM it is still pretty quick, and when driving at constant speed on the highway there is no issue at all.
It's almost like a turbo-lag, except the car doesn't have a turbo.
I think the issue is causing the torque to vary, I never quite know what to expect when pushing the gas pedal. And again, it rattles when accelerating.

 

I missed the rattling part, that more than likely wouldn't have anything to do with the APP sensor. Have you checked to see if there are any TSB out there for your car that may be related to the rattling? Also is it more of a metallic rattle or something else?

 

Still, scan tool. Something that can watch things like air/fuel, cam phasing, missfires, knock control, throttle position. Something that can do live data, preferably in a graphed format.

Rattle could be related, might not be.

Wait, you put synchromesh into an automatic?! That is for manuals only! Going to need to flush the tranny 3-4 times to get that cycled out. Put in some fresh Honda DW-1.

 

Thanks for the advice!
don’t worry, it’s a manual

 

I’ve been all over the internet on many different forums, that’s how I ended up trying all the fixes mentioned above.
The rattle is kind of hard to describe, it could be metallic or anything else, and the site won’t let me upload a recording. And it could be totally unrelated I guess.

 

I truly appreciate all the input here btw, please keep it coming

 

You can understand my confusion when you say synchromesh and torque converter. No torque converter in a manual.

 

Rattle could be the catalytic converter heat shield. They like to crack and then make all kinds of noise.

 

You are right, I’m figuring this stuff out in the process. Most of my knowledge comes from browsing other forums, other than that I know little about mechanics. So please bear with me, I’m learning in the process. I read up on the Acura/Honda “shudder” which seems to occur with both manuals and automatics when the wrong transmission fluid is applied. I thought the issue was related to the lackluster performance. After changing the transmission fluid the “shudder” was gone, but the performance issue remains.

 

Could be, but the rattle only occurs when accelerating, and the harder I accelerate the more it rattles. I have never heard it at constant speed.

 

Shoot a video on your phone and upload it to youtube. Post the link to the video.

 

I had a hard time reproducing the issue. The outside temperature dropped so the engine ran better. But listen closely and you’ll hear it

 

Kind of sounds like preignition.

Yeah really sounds like detonation with that ziiitttt ziiittt right around peak torque.

 

Odd, I replaced the spark plugs a while ago but the ones I pulled out looked fine. Also I threw in a recommended engine cleaner recently.
And why would this only occur when I’m driving? At least I’m not hearing it unless I accelerate, and a scanner has never picked up on it so far.
What could be the problem there, and how to solve it before the engine blows up?

 

Plug in a scan tool that can show real time data. It will show if there is knock and if it is pulling timing. That would explain the down on power feeling.

You would only get knock at high loads not cruising around.

Are you running premium fuel as required?

Does it sound like dry rice dropping on tin foil?

 

I'll have to go see my mechanic in a week or so when I have a moment for a decent scan.
As for the sound, I could say yes to that, but that's kind of subjective. The video does better justice.

 

Bad gas? Lord knows what these stations put in their tanks.