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"ratchety" sound when accelerating

13326 Views 45 Replies 18 Participants Last post by  LAN
My MDX has 3700 miles on it. When I accelerate, I hear a "ratchety" (rapid tapping) noise coming from the engine. Seems to be on the driver side. Usually happens about 75% of the time. Has anyone experienced this problem, or have a clue as to the origin of the noise?


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Are you using Premium Gas? Sounds like what they used to call pinging. My standard shift truck makes a sound like that if I get lazy and don't downshift when I’m in too high a gear for the speed. The computers are supposed to compensate for lower octane gas though.
93 octane

It is a similar sound to pinging, that was my first thought. But this sounds more "mechanical", like gears out of sync. I always use 93 octane gas.
Hey, I would take it to the dealer ASAP. We heard a tapping noise under our hood and it turned out to be a problem with the #2 cylinder.

Boy, I have been waiting for a thread on this one...I just didn't have the desire to do it until now. Anyhow, my MDX is 5 months old under 6K miles and have had to send it to the dealer twice. Yes, twice to kill this annoyance.

Hey MDXinATL the "pinging" noise occurs when you accelerate between 25-35 mph. After, it shifts to above 3000 RPMs it goes away. It is most prevalent when you have the AC on . .and the radio turned down, obviously.
My first visit to the original dealer was around March 01. I had their head technician take a spin with me.
Basically, the noise originates from the engine on the driver side. On the invoice the resolution reads - RATTLE WARR REPOSITIONED CABLES AND HARNESS BRACKET AT LEFT SHOCK.
I said great, they fixed the problem.
Come early June, I began hearing it again. I brought it to the same dealer. On the invoice it read fairly similar to the first - THROTTLE CABLES WARR UPGRADED BRACKET HOLDING CABLES AND VERIFIED THAT NOISE IS GONE.

I am hoping that was the last I heard of this noise because it truly takes away the beauty of beaing able to turn down the radio and listen to the engine when you accelerate off the line. I am sure it is a mental thing now...but I am not looking forward to the third time it happens. Did I just ghinks myself?? :(

The dealership didn't give me a positive indication it won't happen again, either.

Oh and yes, do you fill up with Premium Gas seems to be the question I get all the time when I talk about "pinging" or "rattling." Actually it sounds more like the ol' ace of spades card on the front tire of my bmx. I am far from talking about a lemon law situation, because I truly LOVE :) this ride. As long as I have the warranty, I will keep bringing it in.

Anymore on this same bandwagon. . .. first the THUD, now the PING! What next the Skerk?
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Thanks DBirch and PolyTat

Thanks DBirch, I'll bring it in next week. It may very well be a cylinder. I'm just afraid that when I bring it in, the tech will take it on the 5-minute test drive around the block and it won't make the noise.

PolyTat, thanks for your input, but I don't think we're having the same problem. This is definitely not a rattle. It happens when accelerating, all speeds not just 25-35mph. Also, it seems to happen just before the transmission shifts gears, at any speed. It doesn't go away above 3000 RPM, and makes no difference whether the AC is on or off. It sounds like you really are having a rattling problem.

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Not quite resolved, but getting there

The dealer's service advisor and service manager both drove the MDX, and both said they hear the noise on my MDX, but have never heard it before. They're going to check a string of new TSBs they just received and see if any apply. They're supposed to call soon, then I'll bring the MDX back and leave it with them longer if necessary to figure out the problem. I'll update the forum when this is resolved.
I'll be interested to hear the diagnosis and fix. Ours does it, too: Under acceleration, and most noticable in the 25-35 range, radio off, windows open, and uphill (under load). Sounds just like pinging to me.

3700 miles and 92 octane all the time.

I'm hoping it's the cable deal and not a bad cylinder like DBirch's...I would think that mileage would suffer badly if it were a cylinder (our mileage is ~15 stop-and-go at 20-25mph avg and still >21 highway).
re: Roger That

Sounds like a plan MDXinATL. I know it is a royal pain to bring it back to the dealer .. but as long as the warranty covers it, keep 'em busy.
About a month ago, my MDX (Touring + Nav) started making the same noise that is described here. I would say the noise as a kind of mechanical tinkling that is most noticeably from the engine on the driver's side. The noise starts when you step on the gas at 25-30 MPH and evenually disappears during acceleration up to crusing speed.

I picked up the vehicle about 5 months ago but I still have less than 3,000 miles clocked. It went into the shop today so I'll keep you posted on the outcome. To their credit, the dealer acknowledged the sound is a problem. I was worried that I would have a hard time explaining it.

Incidentally, the engine noise associated with using an incorrect grade of gasoline is called "pinking" in the UK.
I always use Premium gasoline so the "pinking" is at least not self-induced.

Below is a link to a web page that includes a pretty good definition of "pinking."

Regards to all DFW, Texas MDX owners.
Yes, that's the noise. Interestingly enough, I also picked up my MDX about 5 months ago. I'm very interested to know what your Acura dealer says, since mine wasn't sure what the problem was.

Also, "pinking" in the UK is called "pinging" in the US. I've heard pinging, and this noise is definitely not a ping. Also, I use premium (93 octane) gas so it shouldn't be an issue.

Please post your findings from the dealer with regard to the noise!


Welcome to the MDX forum. I too picked up my MDX about 5 months ago - President's Day Weekend to be exact.
I am truly convinced it is not the grade of gas being used. On one of my trips to the dealer, they said they pumped out the gas from my MDX and refilled it back up with "supposed" high octane gasoline. Still there was not any difference, not that I don't use anything but the 92 grade.
It has been almost two months since the last time I brought it in and so far it has been ping-free!
Good luck and let us know what your dealer thinks it is...curious
Pinking noise resolution

Well, I got my MDX back last night and the problem was diagnosed as a "fuel problem." The write up explains that the mechanic added a "fuel additive" to the tank and took it for a 10 mile drive. This seems to have fixed the problem.

Also, they stressed the importance of using a premium fuel and recommended the use of a "high-quality" gasoline. I normally buy my gas at my local Albertson's grocery store pumps as they seem to be a little cheaper.

For now, I'll run a few tanks of Chevron (with Techron) through the engine and keep an ear to the engine for any return of the noise.

This seems like a good fix. They even hooked-up the vehicle to a diagnostic machine and everything else checked out ok. I was also concerned that my average MPG in the city seemed low at 14-15. I was also told the MPG is about average for other MDXs they have seen.

Hope this helps.

Thanks for the update. I've been using Chevron w/Techron and Amoco Premium (both 93 octane) since the day I got my MDX but it hasn't helped. Do you know what type of fuel additive they used? I'd like to try it myself.


Well as we continue the search for a definitive diagnosis and fix, I thought I'd add my latest experience:

I'm not taking mine into the dealer til the 7500 service, which is still a few months off for us 1k/month drivers, but yesterday I switched gas stations.

Filled a bit less than 3/4 of the tank with Chevron Supreme (92 octane) and the rattling/pinging is significantly diminished, though still there a bit. Was using Shell 92 (which, oddly, is now 91 where we live) before.

Don't know if it's psychological, but there also seems to be more low end grunt (power) with the Chevron gas. I'm going to run another couple of tanks of Chevron through to get 100% Chevron in the tank and will report back.

And, I'm still going to have the dealer check it -- there shouldn't be pinging with 91 octane from any gas station, IMO.

Would you mind telling us which dealership you're going to?

My dealer is Ed Voyles Acura, P'tree Industrial Blvd.
All I could get from the service rep was that they used an after market "BG" fuel additive. He couldn't remember the exact name or although I think he meant that BG was the brand. Sorry I'm not being very helpful here.

The good news however is that the pinging noise has gone and the vehicle is running much smoother again. I was going to wait until I had clocked enough miles for the first service but that could still be a couple of months from now.

As long as it is under warranty, I would recommend taking the vehicle into the dealer.


There's a fuel additive called BG44K. I found a discussion of it on an Acura NSX site ( However, I can't find where to buy the stuff. I'll try calling my dealer, maybe they'll give me a can to try out.

On one hand, I hope it takes care of the problem. On the other hand, I hope it doesn't take care of the problem because I don't plan on buying a can of this stuff for every tank of gas, especially when I'm already using Chevron w/Techron.
Just bumping this thread up to see if anyone has found resolution and, if so, what, to this issue. BTW, I've added this to the Knowledge Base for permanent tracking and resolution. You can Click Here for that KBase entry.
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