My engine has started knocking the last month or so. It doesn't do it all the time but when it does it's at low RPM's and usually with the AC on. If the car is warm it can do it w/o the AC. It doesn't knock when idleing or when the RPM's are up. Any ideas?

 

Does it only do it while driving or will it do it during nuetral rev.

 

It only does it while I am driving. Mainly in 4th or 5th going up hill and I don't downshift or when I start to accelerate at low rpm's. Sounds fine in nuetral.

 

Is your car tuned? what octane fuel do you run?

 

Not tuned. I run 87 octane usually. We have had a gas shortage here lately and I have had to put in what I could get. Some premium(93) and some mid-grade(89).

 

How many miles on the car. A couple of things to check and/or change are the PCV and fuel filter, if one is bad (or both) that could cause the car to run lean and knock under load.

 

It has 107,000 miles. I was actually going to change the fuel filter tomorrow. I was wondering if that could be part or all of the problem. Thanks for the suggestion.

 

I changed the fuel filter, oil (&filter) and cleaned the air filter. I also added some lucas fuel treatment. After driving for a couple of days the knocking doesn't seem to be as noticeable. Maybe the fuel filter change took care of the problem.

 

Are you talking a pinging or a knocking? There is a much big differance between the 2. I think you are talking about engine pinging.