Geckoboy

Hi,

I have a 2003 Acura TL-TypeS. I brought it to the service center yesterday because there is a low thumping noise (sounds exactly like the bass on a stereo cranked up). While it's "thumping", the idle goes down to the point where the car nearly stalls, and at the last moment, the idle goes up above 1000rpm and back down, then the cyle starts over. It doesn't happen all the time, but it does happen more often then not. I was able to show it to the service guy. At first he thought my stereo was on and I had the bass pumped up (which is exactly what it sounds like). Both he and the tech he brought out promptly noted that they've "never seen this before".

Here are the facts:

1) I had the transmission replace a few months ago due to hard-shifting

2) I had the timing belt tensioner recall done shortly after

3) After the transmission was replace, the car's fan would go on everytime I would turn off the engine. A couple of weeks after, the car would overheat. I brought it to the dealer and they blamed the problem on an air pocket in the radiator.

4) Also shortly after the transmission was replaced, this thumping/idle problem is happening.

I called the service center last night to see what's going on and they told me that they called the corporate tech guys and they've never heard of this problem. They also check the "technet" or something like that, and no one has reported this problem. They're having their lead/foreman tech take a look at the car today.

Also some more facts:

1) After the transmission was replaced, I swear I feel a loss of power, it also seems like the gear ratio has changed.

2) After the transmission was replaced, there is a hissing noise when I accelerate the car (under heavy acceleration)

3) the thumping/idle problem does NOT occur when the engine is cold.. only after it's warmed up does it happen.

I'm not really that knowledgeable about engines, but has anyone ever heard of this problem? It seems that it all came about after the transmission was replaced. It scares me to think that no one has a clue on what's going on. It's practically a new car and I'm already having doubts on the reliability on Acura's.

Thanks,
Chris

Geckoboy

Also, I forgot to mention, no dashboard indicator lights lit up, nor did the computer log any error codes.

Geckoboy

I just called up the dealership today and they told me the case was due to a faulty TCS sensor, which is some sort of mass airflow sensor. (again, I'm mechanically challenged, so I dont know the terms).

They said the when it malfunctions, the tube doesn't open and close right, which results in the Bass-like thumping noise, as well as the idle stalling.

It sounds good to me, but since I dont know much about engines, does this explanation sound like it holds water?

Sham

I was going to say it sounded like a loose vacuum hose. I think I remember where the TCS sensor on my 5th gen WAS, cause it was taken out when my short ram went in. Hehehehe. My dad asked what it was, I said "extra parts..."

Geckoboy

Well, they replaced what they needed to, and the problem is still occuring. They're all baffled.

What usually happens at this point? Do they bring in a specialist from Acura?

chrisexv6

This is odd, it sounds a tad like what Ive been dealing with.

Driving my car, I swear it feels like its lost quite a bit of power. Dealer doesnt think so, but then again the dealer hasnt driven the car everyday for the last 4 years My tranny was replaced (partly because of this issue, and partly because of a noise the car was making.........turns out the tranny wasnt the cause of the noise, but this issue still exists).

Anyway, the fact that you feel a "power loss" and the fact that it seems to be wanting to stall, almost points at possibly being the torque converter, or whatever controls it. Lately, Ive been noticing 2 things:

1. if my foot is off the gas (coasting, in traffic, whatever) at 60mph+ and I start pressing the gas slowly (I dont beat my car up, so this happens a lot) , the RPMs actually drop 200-400, then go back to where they started, and then the car accelerates. Remember, the RPM loss occurs with my foot ON THE GAS. Sounds wrong to me, dealer said its normal.

2. if Im driving in the speed range that the torque converter should be locked up (Ill explain later), and I give it about 1/4 throttle, the RPMs go up about 200-400, then back down 200-400. It translates almost into a mini-slip in the tranny. Almost like the torque converter should have unlocked, but it didnt. This is also accompanied by being able to hear the tone of the engine change. When the RPMs jump, you can hear the engine accelerate, and then all of a sudden it hits a brick wall, and you can hear the engine bog down. If I dont move my foot off the gas, or push more, the engine will bog for a little, the car gains very little speed, and then eventually it "clears up" and the engine tone goes back to normal acceleration, and the car begins to gain speed at a normal level. Its almost like the sound change you get if you drive your lawn mower over a large pile of grass.

At this point, Ive gotten Honda involved, because Ive been to the dealer 5 times for the first issue, and they told me its normal. Now the second issue has started, and Id like to see them pull a car off the lot and show me how "normal" this is.

Anyway, the torque converters on our cars will go into a "lockup" mode when you are at highway speeds. Thats pretty much "automatic overdrive" to improve fuel economy. When we press the accelerator, the converter should unlock almost immediately under most conditions. My theory (not a mechanic, but I know how stuff works ) is that the converter is either unlocking too slow, not unlocking at all, or not unlocking completely. This, in essence, holds back the car from accelerating.

My appointment with the dealer is on Monday...........Im bringing the car there, and Honda is going to call them to find out whats up. What is odd to me is that issue #1 occurred both before AND after replacing the tranny, which leads me to believe the tranny is not the issue (what are the chances of getting a bum replacement, as the 3rd tranny in my car?) after 6K miles. Its possible, but not likely. But I cannot think of anything that would cause what Im thinking is the issue. Or, it could very well be an engine issue, but Im leaning away from that because I only see these weird things during highway speeds, which is normally 4th gear. City driving doesnt feel nearly as bad, so Im not 100% sure.

I will report back after Monday, however. Im very hopeful that between the two things I see (and I can recreate at will, mind you) and Honda getting involved, my dealer will have a resolution. I even told Honda Im prepared to let them keep the car for as long as necessary to find out whats going wrong. The big hurdle, however, seems to be getting my dealer to admit that there IS something wrong in the first place.

-Chris

Geckoboy

Well, after a week, they fixed it. The official report states:

"A THUMPING TYPE SOUND IS HEARD WHILE VEHICLE IS AT IDLE.
THE IDLE DROPS DOWN CLOSE TO STALLING AND RISES BACK UP.
IDLE IS NOT CONSTANT. NO WARNING INDICATORS ARE ON.
FAULTY TCS VALVE AND THROTLE BODY ASSY.
PER TECH LINE REF#1304494, REPLACED TCS VALVE WHICH DID
NOT COMPLETELY CORRECT PROBLEM. THROTTLE BODY WAS REPLACED
NEXT WHICH COMPLETELY CORRECTED PROBLEM. TEST DROVE VEHICLE"

I am not hearing the thumping sound anymore, and the idle is steady now at about 800rpm.

Any know how to get the info referenced by "TECH LINE REF#1304494"? I'm curious to see exactly what that says.

MrFatbooty

"Tech line ref #1304494" sounds to me like they called up some kind of Acura headquarters tech line and that is the reference number for the call.