Noise on Throttle Tip-In

[orangeblue]

Last week, my car started making a weird noise, which I thought might be rocks pinging against the metal tray under the motor. The car has 45k miles on it, just had an oil change 2 weeks ago at the dealer.

The noise happens most often accelerating from coasting or neutral throttle. Right at throttle tip-in, the pinging noise starts. Usually 2-3 pings and it goes away, most prominent in 5th gear. No CEL, no overheating. Oil level and coolant level normal.

Any ideas? I'll probably be going back to the dealership soon, but thought I might get a more informed opinion here...

[roddy]

Is it possible that you or someone else accidently filled the gas tank with something les than 91 octane?

[FirestormFRS]

Sounds like detonation/knock whatever you wanna call it.

[westendRIOT]

I have the same problem on mine occasionally. There are a few threads on the issue but I haven't seen a good explanation yet, other than a bad (low octane) tank of gas or hot temperature causing some pre det.

I notice it most after easing into freeway traffic after a hard onramp acceleration. One of the threads was talking about the ECU not backing off fast enough after finishing a hard pull and getting some knock on tip in, which matches your report. And it was happening to me a lot a few weeks over the summer when temps were into the 90s/100s.

Dealerships around me straight up said they can't/won't do anything about it unless it happens consistently. I just passed 30k mi, but it's been happening for as long as I can remember.

Subbed 4 more input...

[humfrz]

Maybe you got hold of some "bad gas".

You might try filling up from a different station, see if that helps.....


humfrz

[orangeblue]

Took it to Toyota dealership last week. Tech insisted it was the Eibach springs (which have been on the car for at least 35k miles). Even the service rep didn't buy it. In a fit of annoyance, I took the car home on Saturday, and my dad and I swapped front strut assemblies (his are stock, less than 10k miles). Took it back and went through the "I told you so" routine, they finally agreed it wasn't the springs. Took it home, swapped back, and dropped it off again.

The SET rep is coming to look at the car tomorrow.

[orangeblue]

Final update: dealership techs called out SET tech because they thought it was my transmission (which they had already replaced once, before 10k miles, for crunching into 4th gear). SET tech diagnosed the problem as the direct injectors, specifically one where the teflon seal had vanished (probably burned up by combustion chamber blow-by). The pinging noise was actual "pinging" of the engine, uncontrolled detonation caused by lean running; engine was sucking in unmetered air past the injector, leading to super lean AFR in the combustion chamber.

They replaced all four direct injectors and car now runs fine without weird noises. And they're going to be getting the bill for re-aligning my car.

[SteveIsBored]

Originally Posted by orangeblue

Final update: dealership techs called out SET tech because they thought it was my transmission (which they had already replaced once, before 10k miles, for crunching into 4th gear). SET tech diagnosed the problem as the direct injectors, specifically one where the teflon seal had vanished (probably burned up by combustion chamber blow-by). The pinging noise was actual "pinging" of the engine, uncontrolled detonation caused by lean running; engine was sucking in unmetered air past the injector, leading to super lean AFR in the combustion chamber.

They replaced all four direct injectors and car now runs fine without weird noises. And they're going to be getting the bill for re-aligning my car.

How loud was the pinging? Would you consider it faint/light or was it pretty loud

[orangeblue]

Loud enough that two passengers riding in my car asked me about it. It was very noticeable. At first I thought it was my loaner tires kicking up rocks onto the underbody panels (was getting new tires put on my rims, so running some borrowed rims/tires). The car makes a lot of subtle noises that I'm the only one who really notices (the high-frequency vibration from the Kartboy shifter being the main one, it needs to be re-greased), but this was VERY obvious.