Alright, yesterday I started hear a low clicking noise, but loud enough so I could hear it inside the car. It was about 2-3 clicks per second, but I was like 100' from where I was gonna park so I decided to check it out today.

Start it up this afternoon and it's clicking 3-4 times a second, and gets a little louder with revs. Could this be knock/piston slap? I've never had any problems before.

Here's the mods list:
Gutted stock uppipe
Bosal twin dump downpipe
Bosal catback
No EM (I know that's bad)

I've been running this way for ~45k miles, with no problems. I have a CEL from not doing a fix for the d/p, so that's not going away without EM. Any ideas on what this could be/how I could fix it? I was thinking of disconnecting the battery and pressing the brake pedal until it drains to do an ECU reset, hoping maybe that will fix it, but I don't know. Help me if you can.

My guess is it's an exhaust leak. Check both ends of the up pipe. I assume it gets FASTER with revs?

--Dan
Mach V
FastWRX.com (www.fastwrx.com)

Alright, yesterday I started hear a low clicking noise, but loud enough so I could hear it inside the car. It was about 2-3 clicks per second, but I was like 100' from where I was gonna park so I decided to check it out today.

Start it up this afternoon and it's clicking 3-4 times a second, and gets a little louder with revs. Could this be knock/piston slap? I've never had any problems before.

Here's the mods list:
Gutted stock uppipe
Bosal twin dump downpipe
Bosal catback
No EM (I know that's bad)

I've been running this way for ~45k miles, with no problems. I have a CEL from not doing a fix for the d/p, so that's not going away without EM. Any ideas on what this could be/how I could fix it? I was thinking of disconnecting the battery and pressing the brake pedal until it drains to do an ECU reset, hoping maybe that will fix it, but I don't know. Help me if you can.

My guess is it's an exhaust leak. Check both ends of the up pipe. I assume it gets FASTER with revs?

--Dan
Mach V
FastWRX.com (www.fastwrx.com)

Dan,

It's definitely a serious issue. I started it up today and took a look at the motor at idle. The timing belt seemed a liiiittle off, and I think something is up with that or any surrounding bearings. I called AAA and had it towed down the road, where they are replacing my water pump, timing belt, and timing belt tensioner bearing, as I'm at 90k miles and need it anyway. If that's not the problem, they'll diagnose it and call me to "OK" the fix.

you can see your timing belt at idle...?

how does it idle? id get a compression test on it.

In what part of the engine are you hearing that? I am having a similar issue. I hear the noise specifically on the passanger side of the car.

clicking which does not change in frequency with respect to rpms and originates on the RH side of the car is the boost control solenoid.

you shdn't hear the bcs at idle tho, only on throttle....

Listen for internal issues with a stethescope and external issues with a hose. There are plenty of things that increase with RPM.. Namely everything in or on the engine that moves.

Piston slap is a hollow aluminum sound (tuck tuck tuck). Usually loudest when cold and decreasing as the engine warms up. Also louder under light throttle and goes away under heavy load. Piston slap is pretty harmless though very annoying.

Valvetrain noise is sharper noise and typically gets worse as the engine heats up. More of a "tick tick tick" sound. Also loudest around 1500 rpm.

Lose coil pack or plug can also be your problem. Engine temp usually has little effect and it's a sharper "tick tick tick" than the valvetrain as it's not muffled by the valve cover. Also seems to get louder at specific rpm's but not any given range.

Rod knock is death. Much harsher sounding (tack tack tack) and increases with load. Doubtful this is what you are hearing.

The rest of the noises are usually pretty easy to locate by just listening through piece of hose. Helps narrow down the noises you are hearing so you can find out where they come from.