1994 V6

Hey everybody im new at yota tech, i just created this account a little while ago because i have a 1994 3.0 V6 pick up with 95,000 miles on it. Strong running truck, however whenever i put the truck under a load or climb a hill it has a pretty bad rattling sound and it will come and go as i climb the hill, almsot like a pinging sound. i have ran high octane gas, lucas fuel treatment, the whole 9 yards, and i cant fiigure it out!! any ideas?

jason191918

is it a rattle or a ping? pretty different noise.

BC Rider

Under load could mean higher rpm if you have an auto. If so it could be the shield on your catalytic or another rattle. Does it rattle when you rev it up in neutral?

Hotrodder

Now correct me if I'm wrong but running higher octane fuel can cause pinging. So under load on higher octane fuel you may get pinging from that I believe.

TNRabbit

WRONG. Pinging/rattling is usually detonation/pre-ignition & is caused by too low octane fuel, too high compression, or (most likely) too far advanced ignition timing.

First, short TE1 & E1 in the diagnostic port by the under-hood fuse panel & check your timing with a timing light; should be 10 BTDC with a warm engine at idle.

If that's right, there's a another reason it's pinging/rattling. I'd suspect carbon build-up next (causes compression to be too high). That can be checked with a mechanic's camera. A couple of Seafoam treatments & regular use of it in the fuel tank should clear that up if it's the issue.

After that, I'd check your compression (warm engine, all spark plugs out, coil wire removed, throttle wide open). You should have between 150-172 psi, but more importantly, the cylinders should be within a few PSI of each other rather than all over the place.

Let us know what you find.

Hotrodder

I stand corrected..not that I questioned you but I always thought I was told high octane fuel caused pinging..upon looking it up, you are absolutely right. Good to know

ThatGuy1295

My 89 ping's under a load. The pinging is quiet, high pitched, and inconsistent.
But 250,000K is a good excuse.

Make sure its not just a rattle. or ignition timing like mentioned above.

1994 V6

im chekin the timing belt and ill let yall know what it comes to be,

1994 V6

its more of a ping, but it comes and goes like a rattle

1994 V6

no it doesnt rattle in neutral, and its a 5 speed so when i put it under a small load like before i change gears climbing a hill, it pings then

1994 V6

im checking the timing in a day or two, and yea its pretty high pitched and consistent!! however mines got 95,000 on original engine and all, haha i dont think its normal

1994 V6

its not the timing, we turned it up,, and down, and nothing changed, so i thought it might be the exhaust pipe, or the catyliac converter, but i crawled up under it and nothing happened, no rattle or anything. any more ideas? im gunna check compression next, and if that aint it, ima redo the plugs and wires

Astralplane

Check the heat shield connected to the exhaust down pipe.
On mine, the clamp was loose because the material between the clamp and down pipe disappeared. I wedge some bendable metal between clamp and down pipe.

Wrenchinjoe

+1 on TNRabbit's advice.

A couple of folks have suggested various exhaust related parts to check, you can bang on the pipes, catalytic converter, muffler, shields, etc. with a gloved hand and if something is loose you should be able to hear it "rattle". That is what the guy at the exhaust shop will do while the vehicle is running.

"Pinging" or detonation on the other hand typically occurs under load (ie. 5th gear going up a hill on the interstate), and sounds like valve clatter noise.

You should read the CEL codes and see if it is throwing any errors for the knock sensor. That device is supposed to minimize detonation, and if it is faulty or if the wire pigtail that connects it to the ecu is faulty, you will have pinging. That typically throws a code, but worth checking.

Good luck.

TNRabbit

Not exactly true; if there's a problem with the knock sensor, the ECU will retard timing to 0 degrees BTDC & your performance will go to h@ll.

Wrenchinjoe

I stand corrected, thanks for helping me better understand how that works.

Hotrodder

On a stock 3.0 4runner, is there only one catalytic converter in the y pipe? Between the two manifolds or did the redneck before me remove them? I can't see the whole y pipe in my runner because it's between the block and the firewall under the intake but it looks like the cat is there..anybody got pics of the cats so I can compare and do the "knock" test mentioned above?

Wrenchinjoe

The only catalytic converter should be in front of the muffer, roughly under the driver's seat. I think you are describing the crossover pipe that routes the exhaust from the passenger side manifold, behind the block, and connects to the driver side manifold @ cylinder #6.

Hotrodder

Yes, I would not have thought the cat was in there but it was either there or the previous owner removed it..which looks like he must have. Would not having a cat effect the mpg?

ThatGuy1295

From what your describing it sounds just like mine always has, and still does.
Toyota does recommend valve adjustments every "?" , well its in the book. But does sound valve related on mine as well. Adjusting the valves is no picnic either. Involves shim's and patience. But the inconsistency doesn't suggest valves. Typically valve noise is very consistant. U got me on this one. And I even replaced the cat on my truck and still had the noise. Radio definitely has to be off and the windows rolled up to hear it, but its there.