Engine noise at idle

[sbrownbw@aol.com]

After my 1999, 4.0 liter ranger is warmed up, the engine (or exhaust?) will make a noise at idle. The best description of the noise is like someone is making a monotone hum through a megaphone. It is a fairly loud noise. It is an intermittent noise but only happens when the engine is warm.

[ABE]

I have heard of a problem like that being caused by the main air inlet tube to the engine resonating at idle and low speed. I cannot remember the fix, but I think it involved a replacement part. Try holding or removing the inlet tube and see if the noise changes.

If that is the problem, I might be able to find where I saw it and the solution.

Hope this helps.