Rattle on initial acceleration
 

Hey everyone!

This only happens once the car is good and warmed up, during initial acceleration (stop sign, red light, going slow then hitting gas) there is a rattle that comes from the car for a second then stops after the car gets moving.

Best description I can think of is how a diesel truck sounds, very similar. Anyone else ever experience this? This is my first Acura so I'm not too sure

My car is a 2012 sh-awd with 47k km, any help is appreciated!

It could be a loose heat shield that is rattling, early 3rd gen TL's had the same issue and it required tightening the bolts that hold on the heat shields.

Hmm, I thought of that (although I didn't check) but wouldn't that happen constantly? This rattling only happens once the car is warmed up or would that even make a difference?

My car does the exact same thing. It annoys the hell out of me. I took it to 2 different dealers, they could not reproduce the rattles. They ended up doing what they call a PCM update, It was no help. I might just have to live with It.

Its the heat shield that protects the passenger side drive shaft from the rear catalytic converter. What csmeance mentioned above, its a long lasting Honda issue that hasn't been resolved for the past ~10 years (even 7th generation Accords use to have the same issue back in 2003). What I did I tighten the bolts and also painted the shield with silver heat paint at the edges without removing it, to cover some of the rust (the same you use on brake calipers) and the rattle went away.

Does it sound like you're dragging a chain? Kinda like marbles in a tin can? If so, it may be a fuel issue. I found that the 3.7 liter engine is extremely sensitive to fuel. I switched to sunoco (93 octane) from one specific gas station near me and the pinging completely disappeared.

That could very well be it. There are some threads here way back that people reported the dealer changed spark plugs. Some were bent during installation causing cylinder misfires that didn't even register with the ECU as errors. The Honda diagnostic system can detect those so a dealer may be able to check. A higher octane may have somewhat fixed the problem because of the delayed ignition but that doesn't mean the problem went away completely.

I have the EXACT same issue with my 09 SHAWD. I drive the car until it's fully warmed up. Stop for a few minutes, then drive off and during the FIRST acceleration, there is a rattling sound. After that the engine sounds fine.

My best guess is that there is something happening with the timing/valves. Perhaps there is a faulty sensor giving the ECU bad readings and in return the ECU advancing/retarding timing incorrectly. Maybe the knock sensor reading incorrectly when the engine is warm???

^^^^^

Are you talking about engine pinging ?

I also noticed this issue. It sounds like a heat shield or something but when I put the car on a hoist and knocked around, I couldn't find any sort that sounded like that. Usually happens with acceleration. No clue what it really is.

Not sure if pinging is the correct word to describe it. It sounds like a diesel engine for a couple of seconds then goes away. As I said, this only happens during the first time I accelerate after the car has been restarted. The sounds is mostly evident when the tach reaches 2000 rpm or so while the engine is under load during normal acceleration.

Was anyone able to find a fix for this?

No solution has been proposed in this thread but it does sound like the next thing to try is dump a can of octane booster from the store in your tank and/or accelerate with less smash on the gas pedal.
The pinging or pre-ignition sound is typically described as sounding like a diesel engine and it goes away because the engine management computer senses the undesirable condition and adjusts engine settings to control it.

A guy on the FB group mentioned replacing a gas purge (EVAP Purge?) canister in the engine bay that fixed his diesel noise.

MINE DOES THE SAME THING 5 years later...did you ever figure out what it was? or just how its supposed to sound?

AND ive ALWAYS used 91 Gas CHEVRON or 76 and even once a month Cleaners. Dealer says fuel system is in excellent condition. Several techs have told me thats normal when the car is under acceleration load.
its like a metallic gargle type sound..very diesel sounding... I refuse to accept its normal You have this amazingly tuned engine, thick with power...and you mean to tell me a metallic gargle is NORMAL? I dont think so.
Im gonna try to record it and see if anyone else hears it.

MINE DOES THE SAME THING 5 years later...did you ever figure out what it was? or just how its supposed to sound?

Honestly, after a few months it stopped, not sure what was causing it or what "fixed" it.

Now onto my other problem, oil leak coming from somewhere on the passenger side, it's not much, but making spots on my driveway isn't cool!!

Check your oil filter!

I've been having this problem. I did record it and can post it if anyone is curious. Lasted for a month or two and then suddenly went away. Brought it into a shop and they couldn't find any codes though they heard the noise I recorded. They didn't know what it was...anything from spark plugs to belt or fuel pump or engine issues. Ended up starting with swapping the plugs and doing oil change/filter, though the problem has recently recurred. I HAVE noticed (and someone else maybe chime in if they've noticed this) that on my recent long drive to Vail from Denver that my highway gas mileage is down quite a bit (avg like mid 20s with very conservative driving) and even on straight/level highway driving at 75 I'm average low 20s. acceleration seems to be poor at those speeds and often needs to downshift 1-2 gears to accelerate just a couple MPH to maintain a cruise controlled 75. Anyone figure this out yet?

Can you record and post in here?
My TL does the same thing but it's intermittent and seems to go away when the weather is warming up..

The rattle is back and as bad as ever. I thought I'd put the issue to bed and see if it's pinging and related to octane. I crossed my fingers and filled up with a tank of 87 to see if there was any correlation.

Unfortunately, it seems like it is related. The noise was noticeably worse with the lower octane, and could be reproduced at almost any time when the engine was at higher load (accelerating with the throttle down, especially when at lower RPM). Why is our knock sensor not working and why isn't timing being pulled back to prevent this issue? I've always used premium gas so it should have never been an issue in the first place in a properly working engine, but if there were an issue, the ECU should be adjusting timing to eliminate it.

Any thoughts? I think this needs to be a sticky post until we reach a resolution. It's not normal for a car to do this. Does anyone have a clue if timing is being pulled at all or if our knock sensor just isn't working?

^plug in an OBDII bluetooth module and load up an engine reading parameter app on your phone. read the info it gives you. it will give you all the info you seek.

YOUR car and MY car must be on the same menstrual cycles. mine started the EXACT same thing. Even after a valve adjustment this continues. Please keep me posted on your issue - Il'l keep you posted on mine. ou just gave me a few ideas though on how and what to contact Acura Client relations about, there has to be more of us here with this same issue.

Adn what info specifically would be beneficial? and to who?

^meowmeows asked " Does anyone have a clue if timing is being pulled at all or if our knock sensor just isn't working? "

yes, you can find this info out by plugging in an OBDII Bluetooth module and pairing it with an app that reads engine parameters.

you're awesome. Thank you!

Will give that a shot, thanks justnspace. Do you happen to know what parameter I should be reading and looking at? I imagine it's hard to see if timing is getting pulled since timing is always adjusted based on throttle position, load, temperature, AFR etc... Are you aware of a specific parameter for our engine that shows when knock is detected?

Is Torque Pro still the recommended tool of choice here if we don't own a handheld scanner? Thanks!

I have the same issue in a 2013 AWD WITH 70,000 Km. I used to put 94 octane and never heard it before. For the last 3 fills i switched to costco 91 Octane and started to hear this noise during acceleration under heavy load.

Regarding the parameters to watch, I used to have a ktuner ans was watching Nock control (lower than 0.5 is good) and lower than 0.9 you still making power. I was also watching the Nock retard degree which is derived from the knock control. Also watching the air fuel ratio and the intake air tempreture. May be this sound happen under some circumstances for AFR and IAT.

i will switch back to husky 94 octane and see.

for that rattle was "piston slap". I went from 5w20 to 5w30 and it went away.

Also, strange metalic like rattles...
FOR ME the fix was a fuel additive called Lucas oil Deep Clean 32oz.
Added it on empty tank. Aft 1 tank, it was reduce dgreatly.
I did another treatment (the whole bottle) and it competely went away....

I stopped using it and it evvvvveeeeerr so slightyly returned...

I then switched to a more powerful product called Seafoam motor treatment (2 bottles form walmart).
Added them BOTH at fill up. ANd the noise has been gone ever since.....It has not returned at all.

*My specific Rattle/pinging sound fixed*

This is for those people googling the intermittent rattling noise that most mechanics diagnose as engine pinging or a loose heat shield.

My problem. A rattling noise once the engine was warm, turned off for 10 mins or less and then driven again. Rattle sounds would happen under normal acceleration around 2,000 - 4,000 RPM, and then go away after a short distance. Mechanics guessed it to be bad fuel, a loose heat shield, or a broken transmission / torque converter. I didn't feel any driving issues, it was just noise.

The fix. Drain and fill Hypoid fluid for the SH-AWD transfer case. After that fluid change, I drove around for 40kms in silence with the same fuel, so it was not engine pinging. Its been a bit over 100 kms now and I havent had any noises since the drain and fill.

How many miles were on the fluid?

I'm in Canada, so convert kms to mi. It's a 2010 MDX elite and I changed all the fluids and belts when I bought it with 75,000kms, and it ran great for 4 years (other than a bad bluetooth module eating batteries) Its currently at 139,900kms and is now back to running great. I'm a mechanic, so I sometimes use the acura to tow dead cars to the shop. Since the transfer case holds less than a liter/quart. I'll try to drain and fill the transfer case every 20,000kms.

It can be frustratingly weird.

I had a '98 Saturn with a heat shield that only rattled while accelerating between 45-60mph. Something about sympathetic vibration.

It wouldn't surprise me if the exhaust system is expanding enough when it heats up that something is loose that isn't loose when it's cold.

Did that. Still rattles.

please post. Because the rattle drives me insnane!

THIS IS SOOOOO TRUE. I wonder is a knock sensor a replaceable part?
Would replacing the ECU fix it? This is the rattle persist.
I have replaced practally my whole damed car and the rattle remains.
i have done the following over th epast few years:

• EVAP Replaced
• TRANFER CASE FLUID EXCHANGED
• Valve Adjustment
• New Transmission
• Upgraded to Thicker oil (5w30) - makes a significant different in frequency of the knock/rattle ping
• Replaced Spark Plugs
• a Second Valve Adjustment
• Timing Belt Replacement
• SEA FOAM (In fuel take made it vanish for a few fill ups after using two bottles in one near empty tank)

In all of these Ive noted what helped. But it doesnt fix.
I know this rattle is directly repated to the performance of the car. Because
The drives when the rattle is present, the acceleration is not instant. And merging and passing seems like a real challenge for what used is occasionally effortless. WTF

Acura DID THIS. and not a single peculiarity found. They thought it might have something to do with the fuel/air mixture... making for a rich environement.
Whatever that means. but they replaced parts and that DIdnt do Sh8%^!

At this point ive almost accepted it a how the car is supposed to drive. And it makes me sad that such a beautiful potiential filled car would make such a crappy sound with no other red flags. two Acura Dealesr eventually said (it does that under load). Its normal. Aceept it. NO>

Found this ECU update for the 3.7 MDX:

ENGINE PING NOISE
On some 2010-12 MDXs and ZDXs, customers may experience an engine pinging or knocking noise on
acceleration after each ignition key cycle. While driving the noise eventually diminishes as the vehicle
learns the appropriate ignition timing to reduce knock. The most probable cause is that the premium fuel
available in some localized regions of Canada, especially B.C., has a low Research Octane Number (RON),
and the vehicle has to compensate for this by retarding the ignition timing. To correct the problem, follow
the repair procedure below to update the PGM-FI software with the HDS. The new software improves the
ignition timing learn characteristics.

DIAGNOSIS:
1. Interview the customer: are they using
premium fuel in the vehicle (pump octane of
91 or higher)?
YES – Go to Step 2.
NO – Advise the customer that premium fuel
is required. Use of regular fuel in an engine
that calls for premium not only causes knock,
but long-term use can also lead to engine
damage.
2. Does the engine pinging diminish after an
extended period of driving?
YES – Go to REPAIR PROCEDURE
NO – This service bulletin does not apply.
Inspect for other possible causes such as
loose/defective chassis components, rocks
in heat shields, or defective/loose exhaust
heat shields etc.

Sure sounds like our issue doesn't it?

Software update is no good.

I once asked my Acura dealer to fix the "initial acceleration engine rattling" problem on my 4G TL. They told me the pros and cons.

The pro is that software update will fix the immediate rattling problem. But the cons are that (1) I have to pay for the job, and (2) the rattling problem will come back after a few months (according to their customer feedback). I suspect that latter is to do with the more volatile winter gas formula versus the less volatile summer gas formula, that the engine software is not capable to self-adjust to such a wide range of gas volatility.

My rattling problem is definitely engine pinging because it heavily depends on the brand of gasoline that I fill up with. For PetroCanada gas, the engine will ping like crazy, and for Chevron gas, the engine will have minimal pinging in summer and none in winter. But I still haven't been able to find one gas brand in Canada that will have no pinging all year around.