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Discussion Starter #1
i've got a 92 lx crown vic with @ 90k miles. i cannot use regular gas w/o knock at part throttle.i use autolite 104 plugs.i've replaced the wires,coils,alternator,battery,and ign.switch,&fuel filter. fuel pressure is fine.
i figure i can get a colder plug,but am i just masking a problem?
 

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Don't just mask the problem. What color are the spark plugs when you pulled them out??? It sounds to me like there is alot of carbon build up in your engine. This carbon soaks in the fuel that the injectors are dumping and is ending up running lean. That along with a higher compresion (ratio) due to the taken up space of the carbon causes the knock. Running higher octane fuel simply masks the problem because it burns slower and doesn't detonate. I would first need to know if it is a knock or a ping(it sounds more like a ping). Once you have established that I would run a few induction services through the engine to clean out the carbon. One may make it better but probably won't take care of it all. Also the best thing you can do for a pnging engine(due to carbon) is beat on it once in a while. The extra heat generated at higher loads and rpm helps break up these deposits. Please though, before you do anything(especially beat on it) you need to know if it is a ping or a lower end knock. Please feel free to e-mail me if you have any questions @ [email protected]
 

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Discussion Starter #3
the plugs are white on the tips :whoaa:
it has a sort of rattle at part throttle under load,when i use reg. gas
i'm going to put in some autolite 103s in the next couple of days.(these are a step colder plug correct?)
 

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Knock, ping, rattle... these terms very carefully describe what your car is doing so we can help diagnose over the internet... unfortunately, I couldn't begin to describe each one...
 

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If the plugs are white then you are running lean. Hammer it a couple of times and run some cleaner of some sort through it.
 

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I spray water into mine while at about 3000 rpm. Just enough to bog slightly then let it recover and repeat. Use a squirt bottle on the spray setting,not stream. Spray it into the air intake tube. Believe it or not it will clean the valves and injectors. I do it on my 92 about 2x's a year. Nothing cleans better than steam.BE CAREFUL NOT TO OVER DO IT. Don't do it while very hot either. If you do this, then do it when the car is barely warm and don't over spray. Just enough to bog slightly. BE CAREFUL
 
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