I ve noticed that from about 2000-3000 on the power band, i get a rattling sound; it almost sounds like its coming from directly behind the motor.

I have a 99 4runner 3.4 4wd,148k, also i am throwing a lean bank 1 code.

Any help or suggestions would be greatly appreciated.

 

Are you supercharged? And sounds to me like its pinging if its throwing a lean code. May have a clogged injector.

 

Try cleaning your MAF before you get into anything serious. Then clear the code. See what happens from there. i wouldnt be pushing the engine that hard in the mean time. Just my .02

 

I'm not supercharged, and halve already cleaned the maf and throttle body. It has been about 75k since ive changed my plugs. Have noticed a slight hesitation at those rpms also. Could it be my o2 sensor has failed or maybe that the cat is rusted out and the sound be traveling up through the headers a bit?

 

Sounds like it could be a heat sheild. I would try prying on them a bit just to give them a little more room to vibrate.

 

Thats a new one ill give it a try this afternoon. thanks, still open for other suggestions.

 

change the plugs for one. with regular denso and or ngk its 30k miles. .some go to 50k so i would take care of that just bc its maintanence and yeah check on the heast shield on the cat converter

 

ya but my last 75k were an easy 75k i promise, lol, ya right. everyone knows that our 4run's double as sportscars

 

Hey when changing plugs what should they be torqued to?

 

i had the same hesitation and pinging--changed the O2 sensor and it doesnt hesitate any longer but it still pings a little if i dont run premium.

How many miles on the O2's

 

if its a pinging and not a rattling, its time to get your timing checked...

if its a rattling why dont you have someone get into the truck, rev it up, and you sit down low under it and listen...heat shiels are notorious for this, but usually you can tell that they are under the vehicle...and there is no such thing as an easy 75k, 75k is 75k, change those plugs, they are old and tired, and when you change them you can check for signs of detonation, fouling, etc

 

i agree.. if you motor is pinging try some seafoam.. clean that carbon out and see if that helps.. it helped mine at 75k miles.. doesnt ping at all

 

When i said it was an easy 75k i meant it was a road triping, stop and going, off roading type of 75k. LOL, I have see foamed already, and im sure its not a pinging, its more of a ticking like a empty coke can with rocks type of rattle/tick.

 

I also have this rattling sound at those rpms. It happens to me when I press the pedal enough to accelerate quickly while already at speed, but not enough to make the automatic transmission kickdown to a lower gear. It sounds like stones rattling in a can.

I just changed my spark plugs for the NGK ones a week ago and it didn't make a difference with the rattle. I'm thinking that the rattling is a type or knock or pre-detonation due to the mixture being too lean. I'm going to try to change the fuel filter and clean out the injectors to see if that makes a difference. In my case, it is not a heat shield since I tested all of them and they didn't make the same noise.

Any other maintenance suggestions?

 

mine was doing that the last couple of weeks so i tried the fuel inj cleaner and it seems to be helping. I think next time I am gonna fill with premium but i have to sell a kidney first so that i can afford it.