I have a 92 Camaro with a 305 tbi, when I sit at idle there is a slight miss in the engine sometimes, sometimes its smooth. Also I hear it pinging when I floor it. I've replaced the fuel filter, adjusted the timing, replaced cap, plugs, and wires. I am thinking maybe my injectors might be bad; they appear to be putting out a good misting halo, but I'm out of ideas. Any help would be appreciated.
when timeing the motor, dose the timing mark jump around??? if so a bad timing chain. also you could have a bit-o-carbon built up in the motor and you will get this too.
leaking valve guid's and or seal's can cause this too.
a minor vaccum leak at the intake too.
while idleing spray the intake manifold edges and with carb cleaner if the motor smooth's out you have a leak.
next un-plug the PCV valve. block off the hole and the fresh air inlet hole. soray sone carb cleaner into the vavle cover through the oil fill hole. if the idle change's you could have a intake leak on the inside or valve guid' leaking or valve guid seal's.
The timing chain is in good shape, we ran a complete topend cleaning on the engine, and I haven't yet found a vacuum leak though I will check some more. I am leaning towards the valve guides being worn out. The poor car has 187,000 on the orginal engine, but it was well taken care of. If I don't find any vacuum leaks I'll just assume its in the heads and not worry about it. I am planning on replacing that weak 305 anyway. I thank you gentlemen for your time and speedy answers and will let you know if I find the problem. Thanks again!!!!