NMNorsse
OBS Enthusiast
In park at full temp in a heated garage my '88 k1500 5.7 idles pretty high. I'd guess 1,200 but I don't have a tach. Put it into drive and it idles around 700-ish, which seems fine. It is the fast idle that I'm not so sure about.
To deal with a variety of issues, including age, in the last year I've replaced PCV, CTS, TPS, O2, EGR, IAC, AIR pump, Intake Gasket, TBI base gasket & fuel line o-rings, pressure regulator diaphragm & spring, fuel pump assembly, fuel filter, plugs, wires, cap, rotor, water pump and hoses. MAP tested good and checked for vacuum leaks with propane and carb cleaner without finding anything. Unplugging the brake booster does make idle go up. I also pulled the ECM fuse for 5 minutes, put it back in, turned everything off, set the brake, put it in drive and let it idle for 20 minutes to relearn. It idles smoothly at all times, no stumbles or surges.
Is that fast idle in park at temp the way it ought to be, or am I missing something? It seems too high and I'm out of ideas.
To deal with a variety of issues, including age, in the last year I've replaced PCV, CTS, TPS, O2, EGR, IAC, AIR pump, Intake Gasket, TBI base gasket & fuel line o-rings, pressure regulator diaphragm & spring, fuel pump assembly, fuel filter, plugs, wires, cap, rotor, water pump and hoses. MAP tested good and checked for vacuum leaks with propane and carb cleaner without finding anything. Unplugging the brake booster does make idle go up. I also pulled the ECM fuse for 5 minutes, put it back in, turned everything off, set the brake, put it in drive and let it idle for 20 minutes to relearn. It idles smoothly at all times, no stumbles or surges.
Is that fast idle in park at temp the way it ought to be, or am I missing something? It seems too high and I'm out of ideas.