Im 99% positive that its detonation of some sort. I had scanned the ecm with winaldl and it said my BLM's are at 150-158. This has never happend and i wana know why im so lean? My timing is 7-8*. This is probably giving me the great fuel economy,but crappy et's. Im very fuel starved over the power band. Im thinking of buying an AFPR soon, but I want to know wtf happend! I checked all the vaccume lines around the fpr to see if thats it. No problem with that. Also, there are these 2 other noises, one is a hissing, superchager-like sound, and this tapping noise that can only be heard while in the car... Its not a rocker problem.. that would be louder and I could hear it from the engine. Any insight here? thanks
Alex.

 

hissing+lean=vacuum leak

 

TTT please fellas i need some help or some insight.

 

Try to locate the general area of the hissing sound, then spray around that area. I'm with 91teal, hissing+lean=vacuum leak.

 

"Rocks in a tin can" sound could be loose material inside the catalytic converter. That's how some muffler shops check them, they listen for stuff popping around loose inside. This may worsen as you rev the car when more exhaust pressure is present. Some of the catalytic crap may have blown back into the muffler and be making noise there too. Just a thought...

 

The cat is brand new, so i dont know about that. And the sound is coming from the engine.. I thought it was detonation in the manifolds. As for a vaccum leak, I cant hear it when i open the hood and listen for it.. but when in the car, i deffinatly can hear it. Its very small, but I can hear it. Im thinking around the runners or something.. but other then that, i dont think its a hose. Im gunna have to check it out when I go home again. thanks.

 

a good way to check for vacuum leaks is take a propane cansiter,and let it flow a little bit and just pass it over anywhere u may have a leak,if the idle goes up its where ur leak is. the propane is heavier than regular gas so it will settle down in low areas,just dont ahve the engines fans on,lol. the hissing may be a fuel leak also? mine leaked at the pressure regulator,if u havent yet,check the fuel pressure. GL

 

i had a vacume leak on my power brake booster that I could only hear from inside the car. But that only happened when I was on the brakes.