I just bought my truck with the CEL on...good ol' 71. I finally had time to dig into it this weekend after driving it for nearly a month. I found 2 vacuum hoses crossed in a way that made it so neither the EGR valve or the fuel pressure regulator were ever getting any vacuum. I uncrossed them, tested both, and reset the CEL. So far so good. I also found the TVV behind the intake for the evap can is broken and both hoses going to it were unplugged. That means I had a big vacuum leak which I plugged up. Also, my base ignition timing was at 20* BTDC. I did the jumper thing and put it to 10*. Now with the EGR and FPR working, the vacuum leak plugged, and the timing set what should I expect the truck to do differently? I haven't taken it anywhere too far since I sorted it out. I'm hoping for a noticable improvement in economy, not holding my breath for more power.

Anyone know where I can get a new evap TVV?

 

Im sure it will run alot better now, and with the vacuum leaks fixed and the vacuum lines put in the correct place you will probably get better gas mileage and a slight increase in power.