Menace

Well, after having Ford check into an issue of a "thin metallic rattle" coming from the front underside of the vehicle, roughly around 2500-2800 RPM. The conclusion they gave was that it was preignition. This has been a sound I've heard for quite some time, but thought something was loose or wrong with the exhaust... or the heat shields... and others mentioned the thin plate between the engine and transmission.

I called Brenspeed and they said that my car might be sensitive to their tune, and that they might have to pull back some timing. In the meantime they said switch to a lower octane tune, so I threw in the 87 octane (while running 93 octane in the tank) and bingo... Still making the noise.

What could this mean for my engine, or is it really my engine at all and Ford just misdiagnoised it? I left my stock airbox back in Jersey, so I can't switch it out and see if it still does it. Kinda frustrating.

The engine feels real strong, and several passes at the track would prove that it's running good... but I'd hate for it to be a time bomb waiting to explode.

smythge

Did you put the stock tune back and try it?

Menace

I can't return it to stock without the stock airbox...

modaddict

I know this would be a PIA - but can you record it? Hearing it would help tons in diagnosing...

Menace

It only happens while driving, I can't replicate it simply by sitting there. The sound is like thin metal getting hit, rubbed against, I don't know. It last about 1-2 seconds while in that RPM range. Usually when accelerating, but on my long trip down to FL I heard that sound at that RPM whenever I was cruising... I don't know...

modaddict

I got to tell ya, I don't know for sure without hearing it but it is really hard for me to believe it would be 'pinging' if it is only at a specific RPM range. Normally pinging (detonation) will occur and worsen with increased rpm.

Menace

I don't know, I've tried researching this but it seems I have an isolated issue where people look at me cross-eyed and don't know what I'm talking about.. but I mention "thin-metallic rattle coming from front underside of vehicle" and people go. "Ever heard of Engine ping [sm=smiley24.gif]"

Others, including you Mark mentioned that it could be the plate between the Engine/Transmission, because some models didn't have all the bolts, but my dealership claims mine was made after that.

I thought it was the heat shields.

Someone else mentioned a TSB for the exhaust hangers, from the crossmember, but that turned out not to be it.

I'm at a loss.

explict

I know what you are talking about, my car does it also. Under acceleration in a certain RPM range it will make the sound and go away. It isusually in a high gear at a low RPM such as 4th or 5th at 2000RPM-3000RPM then you cant hear it anymore. It does sound like a ping but I am not sure.

Menace

Mine happens in any gear, not so sure about 1st but it's happened in 2, 3, 4, and 5th.

explict

Well mine also does it any gear I was just giving an example. But is that what you are talking about?