clogged injector or something...Help!!

[((Vibe))]

Hello,

My gf was driving her 2000 Mazda Protege and started to run out of gas, it was sputtering so she floored it to get to the next gas station. She started it back up and now it's making a LOUD knocking sound. I've been told that some garbage probably got sucked into the engine and an injector is probably clogged, and I was recommended B12 fuel injector cleaner. I guessed there was about 5-7 gallons in the tank and put about half the bottle in according to directions. I let it run for about 30 minutes and it's still making that knocking sound...
Now what??

[rustysurfsa]

doesn't sound like an injector. Car would not knock. You know what it could be... I've seen this before. A spark plug has come loose and is be thrown around by the pressure, happend to my gf's honda. If it's not that sound like...sorry...but the head might have cracked or blown a head gasket. I don't know what would cause loud knocking. I've heard knocking from a stuck valve before. All you need to do there is add oil. But that still is not a loud knock. If you find out post, i'm really curious.

[Flash75]

Did you check the engine oil? Is there a check engine light or is the oil pressure light on?

Clifton

[((Vibe))]

Yes actually the oil light was on. I checked the oil and it appeared to only be slightly low...I was thinking along the same lines...but didn't understand why it would make that noise immediately after running on fumes...also figured if it was low on oil,...the oil would have to have gone somewhere...but idk..

Got me a bit worried..

[Flash75]

The knock was probably caused by the oil light being on. The light is there to warn of low or no oil pressure. A car should not be driven with no oil pressure, not even a few miles. My advice is stop driving it and to get it to a garage to have it checked. Suggest towing. Sounds like it may have ruined a rod bearing.

Clifton

[Doug Tatham]

Does the oil light still stay on when the engine is running? If so, get a cheap oil pressure gage and connect it in place of a pressure sensor and see if the pressure really is low (most sensors have the set points engraved on the bottom). If your pressure is low, shut the engine off right away and have it towed to a shop. You'll wipe your engine and rod bearings otherwise. There isn't really any way that running out of gas would mess up your oil pressure, it was probably coincidence. The things that will cause low oil pressure are:
oil pump is bad - easy to fix
severe wear on engine or rod bearings is allowing too much seepage - you're looking at an engine rebuild here.
oil leak - check to see that oil filter is tight, check for oil on the ground under car, check for oil in the coolant or coolant in the oil.