Sorry to highjack this tread, but I went for emission test last Friday.
The next day when I started car in the morning, it had lumpy idle that went away when engine warmed up. But every time now that I start a car cold, same thing happens - lumpy idle that I could feel through steering wheel and pedals.
It's a '01 Vulcan with 153,000 km (~93,000 miles). I installed brand new Motorcraft plugs and changed wiring (Champion) about 15,000 miles (24,000km) ago. Throttle body is also clean and I cleaned IAC
valve last Fall. I tried to unplug a wire from IAC
valve, idle become even worse, that means IAC
has not being changed, but it rattles, so, I guess, it's working. Planing to change it at 100K miles (like Ford recommends).
is not on, but previously I had Small EVAP
leak, but no vibrations at idle. After resetting the light, car passed e-test the next morning with flying colors!
HC ppm (@ 40km/h): Limit 57, mine 8, (@ Idle): limit 150, mine 7.
CO % (@ 40 km/h): Limit 0.32, mine 0.01, (@ Idle): limit 0.7, mine 0.00.
NO ppm (@ 40km/h): Limit 421, mine 9
And the following morning it developed lumpy idle.
Thanks in advance.