1500-2000 rpm knocking 3.4 v6

I was listening to my car the other day and i heard the engine knocking around 1500-2000 rpm in gear. I ran oil tests at blackstone that said the oil is completely free of metals and the filter looked good when i changed the oil(no shavings). you cant really hear the knocking when youre driving but if you hold the break down and rev it you can hear it. I tried to check it out with a stethoscope and managed to listen to it. The knocking didn't sound like metal on metal and was a softer. Part of me thinks that it might be normal engine noise but i am not sure. I've got tons of holes in my exhaust but it doesn't seem like a leak. When i try to recreate it in neutral/park the noise is still there, just not as much exhaust noise and you can't hear it without a stethoscope. What do yalls engines sound like at 1500-2000? and what are some tips to make sure that my engine isn't knocking.

 

Well I assume you have codes with the holes in your exhaust. What codes do you have?

 

Try 91 octane and see if it persists. These trucks were tuned by Toyota to run on the edge of detonation. When I got my truck a decade ago it did the same thing. Switched to 89 octane and it was fine from there. A couple years later digging through the original owners service work and he had the same issue from new and the extra octane cured it.

I suggest the 91 octane as a test, if that cures it, bump down a grade and see if it's happy there. Detonation is bad for the engine and the more you can prevent it the better. These engines seem to be resilient to it as I'm at 217k miles and it's had bouts of it in its life, it's something that happens still due to my current setup regardless of the octane. Still, it's best to avoid it.

Good luck.

 

You sure you don't have an exhaust gasket failure at one of the ports?

 

Maybe something is loose in the engine bay.

 

Run a can of Berrymans B-12 Chemtool through the gas tank to get rid of moisture. If you dump a can of octane booster and the knock goes away, change gas stations.

 

no codes, just a really crappy sounding exhaust.

 

mines at 80,000 so i hope i can get mine that far. Im not really sure if its a detonation issue because it sounds too consistent, ill run some higher octane anyways though to see

 

i mean theres a chance yeah. when i swapped the engine over i didnt swap out all the gaskets. how would i go about testing for that?.

 

They run the exhaust out the back for a reason. Fixing the exhaust is better for you than it is for the truck, and it is good for the truck.

 

ill check that out.

 

It's at least the easiest to rule out and just a couple dollars more than a tank of regular.

 

Possible shitty gas?

 

Maybe a pulley knocking? Take a look in the engine bay while it's running and see if any are wobbling

 

it does ping occasionally at 2000 rpm, that being said i feel like the noise is more mechanical

i know one of the bearings on my timing belt is making noise at idle but im not sure if its related. I've heard an engine knock before and usually the knock will flutter a little when the crank is floating and thats not happening whatsoever with mine. I really need to jack the back of the truck up and give it a good listen. When i had my stethoscope up to the engine i heard some noise but it didnt really sound like metal on metal contact. It was a repedetive thudding like an exhaust that corresponded with rpm from 1500 upwards to 2000. I haven't ever listened to another 3.4 v6 with a stethoscope so maybe the noise is normal? when you get up to 1500 what do you hear? is it totally silent or is there noise?

 

Hard to say without hearing, I would say it's not