MassD

iTrader: (1)

Starts up fine and idles well. its an 84 trans am with a 350 and t5. Its not a rod knock or an arcing wire and it makes this loud banging popping noise above 3700. It sounds horrrrible could be the coil cap and rotors? Or something else? Help!!!!

seibertjd

How is your acceleration? Does it sound like a backfire? Have you checked your timing advance? Where is the sound coming from, can you tell? Is it only when driving or does it happen when the car is standing still? Does it happen while you are giving it gas, or after you let off?

MassD

iTrader: (1)

Its while giving gas both in neutral and driving. Its only on medium to hard acceleration and it isnt a backfire. It sounds like a miss almost. I check the timing right at 7 degrees the advanced is good as well. It sounds like its coming from the passenger side of the motor almost out of the carb its hard to tell. all 4 cylinders on that bank are running around the same temp as well.

MassD

iTrader: (1)

Im thinking it might be a cam. I pulled the valve covers off and the one intake lifter on cylinder 4 is moving slow >:O Ill post a video of how it sounds. i checked the push rods and they arent bent

MassD

iTrader: (1)

http://www.youtube.com/watch?v=baHxG...e_gdata_player

seibertjd

This one might be a little out of my league... I am still learning when it comes to this stuff. Did you check or readjust your valve lash? Is it possible that you have a lifter that is sticking at high RPMs? Just throwing stuff out there at this point.

MassD

iTrader: (1)

I adjusted all the valves both intake and exhaust. =( Looks like the manifold is coming off tomorrow.

MassD

iTrader: (1)

Just got thinking, could it be the module?

DENN_SHAH

iTrader: (1)

kind of hard to tell from the vid, but i believe you have a problem with an exhaust valve not opening properly.
if an exhaust valve doesn't open all the way, the motor will pop back thru the intake. the less the exhaust valve opens, the worse the pop is.
if an exhaust valve isn't opening at all, then you can get the pop at idle.
a rounded lobe on the camshaft is what normally causes it.
flat tappet lifters without the right additives in the oil, mainly ZDDP (which many oils are now missing), and the cam and lifters start eating each other.
from the vid, it sounds like yours is just starting to go away.

if your cam is going away, the only fix is a new cam and lifters.
some people have gotten away with just replacing the cam and lifters, but because the motor will have metal from the lifters and cam in it, i strongly recommend rebuilding or replacing the motor, and preferably going back with a roller cam.

guitarguy92b

glad i found this, im having the same problem with my 92 but its worse, alot worse, it sounds like a back fire and kinda feels like its flooding out, im thinking IAC could be causing some of the problem, and im currently getting around 10-12mpg with a bone stock 305 which is completely ridiculous hopefully both of us can get some answers and help here

ill try and get a video on here of what mine is doing and post it tomorrow, maybe we both have the same problem

MassD

iTrader: (1)

Well I changed the module today and still popping. The only reason I don't think it's the cam is because it idles like a dream and uP to 3000 rpm is fine. Could this still mean that it's a cam? And I was also getting horrible mileage

DENN_SHAH

iTrader: (1)

you said that the intake rocker on cylinder 4 is moving slow, i would almost bet its actually the exhaust rocker.
even though it runs fine at idle or low throttle/ RPM, it can still have one or more lobes going away on the cam.
the more throttle you give it, the more air the motor draws in.
the lobe can still be good enough to open the exhaust valve enough so it doesn't build pressure in the cylinder until you start giving it more throttle.

eseibel67

That sounds like a worn cam lobe.