Help! pinging-dieseling sound, 01 and 03 Jimmys 4.3li

[Benjimin]

My 2003 Jimmy sls 4.3 liter engine has an almost constantly pinging sound (similar to a dieseling sound) when cruising. It goes away when I accelerate. I also have a 2001 slx which is starting to do the same thing but not as bad.

Both start well, run well (other than the sound) and have lots of power. The 2003 has 45,000 miles on it and the 2001 has about 80,000 miles. Both have the original plugs, etc. I usually run regular gas (with 10% ethanol) but I have recently run several tanks of the highest test gas I can find with no noticeable difference.

I'm concerned this will escalate into a bigger problem, head, valves, etc., if not resolved.

Thoughts, ideas, suggestions?


Ben

[old_master]

Possibly the serpentine belt, belt tensioner or idler pulley. Remove the belt and check all pulleys, they should turn easily, and quietly with no wobble. Just a thought, easy to check.

[Benjimin]

Thanks for the suggestion. I subsequently checked and all seem tight.

I did get a tip that a "Knocking" sensor may be the culprit. Now all I have to do is figure out where that sensor is. I will post another question to keep the thread simple.

Ben

[Benjimin]

Where do I find the Anti Knocking sensor ( I believe that what it is called) on a 2003 Jimmy with a 4.3 liter engine? Is ther a way to check if it is faulty?

Ben