Hunting At Idle And Surging At Low Speed - Fixed

[Simple]

For the benefit of all, my car had a strange behavior hunting at Idle and surging at low speed. This happens for a few days every around 400-500km. This is usually caused by the lower butterfly flap in the inlet manifold.

 

I tried a spare MAF that I have and it seems to improve a little but does not solve the problem. I searched everywhere and checked everything, to no avail. Then,,,,, I came up with rather a good idea; I had a meter long plastic tube that I used to fill the Gear Fluid last year. I started the car for 30 seconds then switched it off. I placed one end of the tube at my ear and hovered over parts of the engine with the other end until I heard a faint hiss...

 

The oil pipe was resting over the inlet manifold lower butterfly valve. Due to vibration, it rubbed the casing thin and caused a small hole, hence leakage. Cleaned it with solvent and covered it with high temperature epoxy and repositioned the oil pipe to avoid contact.

 

Problem resolved.