Expert: Ben Deutschman - 2/5/2010

Question
i just bought a 94 grand marquis when i first got it i noticed that when you tried rapidly accelerate or to rev it it would pop like a back fire in the intake i changed the plugs ect i also noticed the oil was low so i added as needed And now it sounds like a rod is knocking or something i just want to know if you can tell me what you may think the solution is i don't want to scrap it but i don't think i could get much with it running this way so if you can help me out you would really be doing me a favor cause i cant afford another car and i might cry i ain't gonna lie a man can cry right lol so if you think it can be repaired with reasonable funds plz let me know

Answer
Based on what you written, I'm afraid that a cheap fix is not an option. Popping back upon acceleration, or upon opening the Throttle even at idle, could mean a burnt Valve, bad Cam Lobe, or vacuum leak somewhere. If the knocking you are hearing is fairly pronounced, not a lighter tapping sound, than that would indicate a spun bearing on a Connecting Rod, and a really pronounced knocking, from the lower part of the Engine, could be Main Bearings. Neither problem can be repaired cheaply, since both require a total Engine tear down in order to get at them, and then Machine Shop work to resurface the Crankshaft, plus new Bearing Inserts, and if you are that far into the Motor, then you may as well have the Block Boiled, Cylinder Bores checked for roundness, and re-machined as needed, etc.