So I recently did a bunch of overdue maintenance and repairs: spark plugs, fuel pulse dampener, valve adjustment and valve cover gasket, etc. Put everything back together and the truck runs worse than ever. Idle is around 500, very rough, and I can't keep it running for more than 10 seconds without goosing the gas pedal. Runs OK at speed, but wants to die at every red light. I pull some codes and get a fault at the MAF. Wonderful. This just got complicated and expensive 
.
Then I remember: when I was doing the valves, I had to pull off the rubber air intake hose assembly. There was a crack at the bottom of the bellows of the #2 hose (the one that connects to the throttle body). Totally hidden. The hose was probably original and the rubber was petrified. I taped it and made a note to replace it later since the part had to be ordered from the dealer.
To get to the fuel dampener, I had been laying on top of the engine, crushing that brittle hose. I felt underneath and what was once a crack was now a wide-open split
. The engine was sucking in unfiltered, unregulated air and running lean. Luckily, I had the new hose in hand, and 15 minutes later the truck was running butter-smooth.
Reading the "rough idle" threads here, I'd bet there are people chasing this problem around. My original crack was probably there for years, and judging from my detonated spark plug tips, the truck was likely running lean the whole time. It's impossible to see until you remove the whole hose assembly. Luckily, the #2 hose is still available new ($70). Tighten down all your ring clamps and supplement the hose seals with some neoprene tape if necessary. You won't get a perfect idle until the intake system is sealed.
.Then I remember: when I was doing the valves, I had to pull off the rubber air intake hose assembly. There was a crack at the bottom of the bellows of the #2 hose (the one that connects to the throttle body). Totally hidden. The hose was probably original and the rubber was petrified. I taped it and made a note to replace it later since the part had to be ordered from the dealer.
To get to the fuel dampener, I had been laying on top of the engine, crushing that brittle hose. I felt underneath and what was once a crack was now a wide-open split
. The engine was sucking in unfiltered, unregulated air and running lean. Luckily, I had the new hose in hand, and 15 minutes later the truck was running butter-smooth.Reading the "rough idle" threads here, I'd bet there are people chasing this problem around. My original crack was probably there for years, and judging from my detonated spark plug tips, the truck was likely running lean the whole time. It's impossible to see until you remove the whole hose assembly. Luckily, the #2 hose is still available new ($70). Tighten down all your ring clamps and supplement the hose seals with some neoprene tape if necessary. You won't get a perfect idle until the intake system is sealed.
