KING

How to distinghish between noisy injectors, valvle taping, and pinging?

ChickenLover

Just a thought: The guys at my muff shop use some type of stethoscope rig to pin point exhuast leaks. You could get one of these, put it directly on one of your injectors to become familiar with it's sound. Then do the same on your valve covers. I bet this would help you distinguish between the two sounds. Pinging on the other hand, should be pretty obvious. While your engine is under load, it will sound like a marbel(s) bouncing around in your engine.

What are you driving by the way? I know on 2nd gen runners the steering shaft seal at the firewall commonly craps out leaving a hole directly into the engine compartment, letting all that normal engine ticking sound into the cab. Leading one to believe that there is an engine problem, when in fact it's just firewall seal.

KING

I would like to know how to distinguish the sounds without taking to a muffler shop, unless it is relatively inexpesive.

Taping, whether pinging or injectors, does tend to get relatively louder when the engine is under load.

I am having the injectors serviced and the timing belt will replaced soon so noisy injectors and any pinging ought to be brought to correction.

I am just concerned since the "taping" has been getting louder over the past week and a half.

I will check on the shaft seal.

It is a '94 P/U.

rimpainter.com

Noisy injectors will be pretty timed at idle on that motor. Noisy valves are somewhat harsh and "impromptu" if you will. In other words, not every one of your valves is going to be out of adjustment to the point of a perfectly timed tapping.

Most exaust leaks, depending on where they are, are timed. So, the sputter will be at a somewhat regular frequency until the engine heats up, which is usually when the sputtering subsides unless the hole is really big or it blew a gasket out.

KING

Got'cha on the valve part.

Interesting, I had never thought of that.

I am going to zero it down on the injectors.

I had never considered the exhaust and yesterday, whilde idling, I noticed the exhaust sound was almost replicant of a short-block 305 Chevy. Only a one time deal though, as it was normal this morning.

Sounds like I am a bit anal and paranoid on engine noise.

rimpainter.com

Yeah, anal like me . You can also see if your truck is missing by taking a dollar bill and holding it up against the exhaust pipe outlet with the truck running at normal temp. A miss will "pop" the dollar bill nice and loud.

Sometimes out of adjustment valves will cause a slight miss that can be detected at idle.

ChickenLover

Join the club. If I have so much as a rattle in my glove box I get mad. When I first got my runner I was baffled by all the noise it made. I tried everything to correct it. I came to find out that the 3.0 is just a noisy sumbitch. That firewall seal made a big difference for me and I just finished adding a sound blanket to the firewall (engine side). So we'll see how that goes when I get the engine back together.