Rear end noise and engine chatter

The mechanic at the dealership said that newer cars, in their efforts to get more mpg's, do this now, that it is common. It usually last for about 1-3 seconds max.[/QUOTE]



The mechanic either is misinformed or lied. Yes, the code in newer ECMs will test a more advanced timing, or a more lean mix, to improve mileage, and yes, detonation will occur under these ECM tests, however, the duration is never intended to be even close to one second.

 

The mechanic lied.[/QUOTE]

Yeah, that's what I was thinking. I never heard the noise, not a single time, until the 10K service. I'm concerned something happened at the 10k to cause the motor noise. Rear end noise is longer term issue. Initially they tried to tell me it was my "aggressive" tires. Which is BS, since I've owned numerous sets of these tires and no vehicle has ever made this sound before. I may try a different dealership closer to me.

 

Yeah, that's what I was thinking. I never heard the noise, not a single time, until the 10K service. I'm concerned something happened at the 10k to cause the motor noise. Rear end noise is longer term issue. Initially they tried to tell me it was my "aggressive" tires. Which is BS, since I've owned numerous sets of these tires and no vehicle has ever made this sound before. I may try a different dealership closer to me.[/QUOTE]


Did the detonation sound begin immediately after the 10k service was performed?

 

Your description sounds to me like classic knock from a lugging engine.

Too much load at too low an RPM, which is why the downshift makes it go away.

Think manual trans on a light 4 cyl sports car, rolling, but only at about 1000 RPM, and trying to accelerate hard in 3rd instead of being back in 1st. Same knock.

To support this idea even further, try running through the gears manually, and upshift when the RPM is in the 3k range.

If that 'fixes' it, it means your transmission is not responding to load and throttle inputs quickly enough.

That's my dime store opinion, but it costs you nothing but a bit of time and fuel to try it out.

 

This is more or less how the mechanic was describing it. His claim was that the transmission is programmed to shift in order to achieve higher mpg's and therefore the side effect is occasionally I'll hear the motor do this. However, prior to the 10k service, I never heard it once. Good idea on shifting manually through the gears. I'll give that a shot. Assuming this corrects things, what suggestion do you have for eliminating the noise under normal operation in D? Dealership needs to reset the ECU?

It doesn't seem to hurt performance or mpg's. A week ago, I achieved my best yet, 25.4, on a short highway trip.

 

Did the detonation sound begin immediately after the 10k service was performed?[/QUOTE]

Yes, pretty much.

 

Has your transmission already had the reflash covered by a TSB?

And not that I think it's in play here, but has the fluid level been checked properly? It's not 'hard', but it is quite specific in how it's to be done. It's worth asking for, since there are many reports of underfilled units, especially the '16 models.

 

I had the trans fluid checked last fall. It was determined to be low, so they topped it off to the correct amount.

I've not heard anything about the trans reflash TSB. I did read a thread on here where people were experiencing all sorts of weird shifting issues, but at the time my truck was performing flawlessly, trans shifted great, and my mpg's were good.

 

The suggestion to fix it, and this is pointed at Toyota, would be to get the ECM flash calibration right. That's it.

 

Was your fluid filed at the 10k service?

 

He may have had ECM and Transmission reflashes if the tech did a "health check" and "update" on the Techstream.

 

If, I can get them to do this. They've been reluctant to do anything without first hearing the noises I'm complaining about.

No, fluid was done last fall when the mileage was around 3-4k.

This has never been done to my knowledge. What should I ask the dealership to do specifically next time I bring the truck in? I'll still probably try the other dealership as the one I've been going to are a bunch of a-holes who seem irritated when I'm there for anything.

 

As far as Them hearing the noise, sure, they will need to diagnose the issue. You may need to leave the truck for a few days. As far as ECM or Transmission reflashes, have the service dept tell you if, at at what mileage, a reflash was done. Also you can request the calibration numbers if the ECM or transmission was reflashed.

 

They never want to keep the truck and always make giving me a loaner vehicle a big deal. Hopefully the new dealership is better about this. Better about everything. Thanks for the info on the reflash info. I'll ask when I go in. What would the calibration numbers tell me?

 

Try the new dealership. If no luck, call Toyota Customer Service, at 1 (800) 331-4331, and open a claim with them. They are technically claims adjuster and not customer service, but you can get what you need through those clowns. Just be firm. They will manage the dealership to try to get your issues resolved.

 

Thank for that number! Didn't know I had any options other than dealing with the moron's at the dealership, or just switching dealerships.

 

Oh.... you have a lot. I can help and there are many others. This is a great site.

 

Well shoot, now I feel kinda stupid for taking so long to post. Love the truck, but the rear end noise and this new engine noise issue is killing me. Others, truck is great for the most part. Seats kinda suck though if you're a tall person.

 

Cheers.

 

Guys, unless you run the tank bone dry (not recommended) then, if there were bad gas still in there, it would just mix with the good gas and have slightly better bad gas. It could take many many tankfuls to get rid of the culprit. I too think it's bad gas.