Pinging without throttle. Stumped.
Thread Starter
Lexus Test Driver
Joined: Mar 2007
Posts: 1,025
Likes: 13
From: McAllen, TX
Pinging without throttle. Stumped.
I have a pinging sound in my car coming from the rear of the engine or transmission area. It sounds like classic engine pinging, with a very metallic tinny sound. I've had this issue for at least three years and its getting worse. Many techs suggest fuel system cleaners etc, and of course I've run em all through the car without any improvement. I also only use premium Shell or Chevron gas. The pinging sound only occurs during coasting, NEVER during any throttle input. It's the worst when my foot is barely touching the gas pedal; not enough to keep the car at a constant speed, but also not a full coast. Does not occur at idle with the car stopped, even if I rev the engine. I've replaced the exhaust y-pipe, and done several thorough checks of the car. All maintenance as scheduled. I do have the original MAF in the car and it has 157,000 miles. Could a bad MAF cause this? Ideas? Anyone ever had a strange unexpected failures of parts that usually don't break or go bad?
Lead Lap
Joined: Nov 2009
Posts: 486
Likes: 3
From: IN
Does the "pinging" sound change at all when hot, cold? Could be a clue there.
Also, does it occur only while in gear (albeit a near coasting) or would a high idle in neutral/park also do it?
Also, does it occur only while in gear (albeit a near coasting) or would a high idle in neutral/park also do it?
Last edited by randal; Dec 18, 2014 at 11:27 AM.
Thread Starter
Lexus Test Driver
Joined: Mar 2007
Posts: 1,025
Likes: 13
From: McAllen, TX
No difference when hot or cold. I can only detect the noise while driving. In park no matter how I rev the motor it will not make the noise; high revs, low revs, stabbing the throttle, gradually increasing the revs.... nothing causes the noise in park. I've even had the car running on a dyno with me under it with a stethoscope and and I could not hear the noise, but the dyno would mimic a load condition equivalent to the car being under throttle so it didn't surprise me that I couldn't hear anything.
A loose heat shield is what you would think it is if you heard it, but I've removed the heat shields on the y-pipe and I checked the remaining shields on the exhaust manifolds and elsewhere.
A loose heat shield is what you would think it is if you heard it, but I've removed the heat shields on the y-pipe and I checked the remaining shields on the exhaust manifolds and elsewhere.
Intermediate
Joined: Mar 2014
Posts: 273
Likes: 23
From: Indiana
No difference when hot or cold. I can only detect the noise while driving. In park no matter how I rev the motor it will not make the noise; high revs, low revs, stabbing the throttle, gradually increasing the revs.... nothing causes the noise in park. I've even had the car running on a dyno with me under it with a stethoscope and and I could not hear the noise, but the dyno would mimic a load condition equivalent to the car being under throttle so it didn't surprise me that I couldn't hear anything.
A loose heat shield is what you would think it is if you heard it, but I've removed the heat shields on the y-pipe and I checked the remaining shields on the exhaust manifolds and elsewhere.
A loose heat shield is what you would think it is if you heard it, but I've removed the heat shields on the y-pipe and I checked the remaining shields on the exhaust manifolds and elsewhere.
Thread Starter
Lexus Test Driver
Joined: Mar 2007
Posts: 1,025
Likes: 13
From: McAllen, TX
I found this video that is showing exactly the same noise I have, albeit to a greater degree. The noise in this video mostly occurs when the revs of the engine are coming down, much like mine, although this car's rattle is audible in park too. I think a loose core inside one of the cats is likely the problem; I've gone through every system on the car and it's the most likely candidate. I am not throwing any related codes though, which I surmise could be the case if the core is only just loose within the casing.
Lead Lap
Joined: Nov 2009
Posts: 486
Likes: 3
From: IN
With your description of symptoms, I am really thinking maybe the torque converter or flex plate. You might try to determine if the torque convertor is coming out of lock-up when this noise occurs or if there is a speed at which the noise is most noticeable.
Trending Topics
Thread Starter
Lexus Test Driver
Joined: Mar 2007
Posts: 1,025
Likes: 13
From: McAllen, TX
Wouldn't the car present with transmission and shifting issues if the torque converter was going bad? Also wouldn't a torque converter problem escalate into a huge failure of some sort sooner than 3 years/50k miles? It used to be most noticeable on the highway, now it's any speed.
ClubLexus Stories
Celebrating Lexus & Toyota from Around the Globe
Top 10 Lexus & Toyotas to Drive Before You Die!
Joe Kucinski
Top 10 Lexus/Toyotas With The LEAST 5-Year Depreciation
Joe Kucinski
Lexus LC500 Convertible Auction: A Preview of Rising Values?
Brett Foote
GX 550 vs TX 550: Best 3-Row Luxury Lexus Family Hauler
Michael S. Palmer
9 Best Lexus Models You Can Buy for Half Price (And 1 You Shouldn't!)
Joe Kucinski
2026 Lexus NX Buyer's Guide: Models, Features, Prices & More!
Brett Foote
Top 10 Reasons to Buy a Lexus TX 550h+ (& 3 Reasons to AVOID!)
Michael S. Palmer
Top 10 Lexus & Toyota Models of the 1990s RANKED!
Joe Kucinski
10 Great Toyotas That Could Have Been Lexus Models
Joe Kucinski
Lead Lap
Joined: Nov 2009
Posts: 486
Likes: 3
From: IN
Wouldn't the car present with transmission and shifting issues if the torque converter was going bad? Also wouldn't a torque converter problem escalate into a huge failure of some sort sooner than 3 years/50k miles? It used to be most noticeable on the highway, now it's any speed.
Thread Starter
Lexus Test Driver
Joined: Mar 2007
Posts: 1,025
Likes: 13
From: McAllen, TX
I've replaced all the engine mounts and ALL the suspension parts, including the upper control arms, steering rack bushings, and inner and outer tie rods. The only time the noise changed was after replacing the two broken front engine mounts, the noise mostly disappeared for a few weeks but then came back. If it is indeed a loose core in the cat, I suppose changing the engine mounts would impart a slight flex to the exhaust system, which could cause the loose core to not be as loose and not make as much noise, but then slowly loosen up again.
Lead Lap
Joined: Nov 2009
Posts: 486
Likes: 3
From: IN
If it were a loose core in one of the cats, could you use a mechanics stethoscope and pound on the cat (while cold and not running) to listen for a rattling noise? That might reveal something especially if you got a different noise out of one of the cats.
Thread Starter
Lexus Test Driver
Joined: Mar 2007
Posts: 1,025
Likes: 13
From: McAllen, TX
Thread Starter
Lexus Test Driver
Joined: Mar 2007
Posts: 1,025
Likes: 13
From: McAllen, TX
Haha I keep thinking the same thing after every repair. Still waiting for the new car feel though LOL. As soon as I fix one thing, something else breaks. Got two nice rips in the driver's seat pad recently...