Hello everyone, I need some help. I have a 1996 Ranger with the 3.0 w/ auto trans. It started making a knocking sound a couple weeks ago but it would only do it when accelerating from a stop, now it has started doing it constantly. I pulled the spark plugs last night and they were toast (the driver side was worse than the passenger side) so I put in a new set but it didn't stop the knock. I'm thinking it may be a timing issue but I just don't know. I had the codes checked and the only one that came up was a bad purge valve but I don't think that should have anything to do with this. If I had to describe the sound, I would say it sounds like something metal hitting the fire wall. It won't knock at an idle or in park, only under load. I've tried checking for any vacuum leaks with carb cleaner, found one small one and repaired it with a new hose.

It won't make the noise in park, it needs to be under load. Like wise if I'm driving and it starts knocking, I can take my foot off the gas and it will immediately stop.

Our other car is currently broke down so we are currently without a vehicle and don't have the money to take it to a mechanic so any help is highly appreciated.

 

In the old days when the ignition system was based on a coil going to a distributor to the spark plugs, the answer was easy: The engine is not timed correctly. Are you able to adjust your distributor to reset the timing on your engine? If so, try doing that to get rid of the engine knock. If not, check out the spark knock sensor. It may have gone bad on you. The fix would be to replace the sensor.

Is the CEL lit? If so, take it to an auto parts store that will read the trouble codes at no charge to pinpoint the problem.

 

You may have more than one problem. Post all of the trouble code Numbers you have.

The under load metalic knock sounds like spark knock/detonation, so things like a vacuum leak, lean fuel shot from dirty injectors, low fuel pressure from a clogged fuel filter, or weak pump, wrong heat range spark plugs, over heated/hot running engine, bad/lower than spec octane gas are some things that come to mind for your suspect list.

Yes the purge valve code you said turned up on the code scan could figure in, if a vapor recovery vacuum line is leaking, so find & fix that problem first.

A read on the old plugs could be helpful, so post what All of them looked like.

You need to get this fixed pronto, as detonation can destroy an engine.