i did the physical check by hand, but it still feels like "hissing" noise somewhere, plus it takes a sec for a car to get moving...once it moves i have no issues... but i need to know if there is special test, lik ethey have for fuel or coolant leak with special dyes, or something visual...or can i do an engine compression test to see where the leak is coming from? I had a new block installed recently(my old one blew), i had guys at mechanic shop reinstall my rebuilt head and intake manifold, but i suspect somewhere during the reinstall they left something not tightened good enough....i checked the header, cat, etc, no leaks there, but it feels like my intake manifold itself might have a leak in it...thats where the sound is coming from....Is it possible that my mani is loosing some pressure thru gasket? and if it is, how do I check for it to make sure.

p.s. my car idles and sounds fine when standing still, but when given gas it "hisses", plus unless i give it enough gas my car wont move, so my part-throttle is ****, but once i reach 2500 rpms, it runs fine....
before the engine install the car run "tighter" at low rpms....i need help...btw I also gutted my catalytic converter during the new engine install, could the "hissing" noise be the result of that?...anybody had they're cats gutted? does it make the same sound ? thx

 

have someone plug the muffler while car is running it will create more pressure and you might be able to detect leak,,,,,,,,yes the hissing could be coming from the gutted convertor and by the way you know that with a gutted convertor your hc will be higher and you wont pass emissions right ??

 

i'm from michigan
...lol no emissions baby

 

well that takes care of that problem then :-)