I am trying to diagnose/solve a high idle issue. I recently dropped a new block and heads into my truck and ever since it has had a high idle problem. It is a 2001 Ram 1500
with 5.2 manual 4wd. I have replaced the IAC and TPS. Recently set the fuel sync and replaced O2 sensor (it happened before all these replacements). The truck will run fine for the first 5 starts. After it relearns the mixture, it will high idle at just about 1500 RPM, but only while moving. If I am going any speed and toss it into neutral, the RPMs will drop but only to 1500 RPM and will only drop back down to idle if I come to a stop, or if I "lug" the engine by putting it in a high enough gear to force it below 1500.. then it will drop to a normal RPM. Any ideas?
JA: Have you located all of the vehicle's oxygen sensors
? Are the wires leading to and from each intact and in good shape?
Customer: Yes. And replaced the upstream sensor recently.
JA: Are you fixing your Ram 1500 yourself? What have you tried so far?
Customer: Yes fix it myself. Replaced IAC, TPS, O2 sensor, cap, rotor, wires, IAT, temp sensor, fuel pump, and had the injectors cleaned.
JA: Anything else you want the mechanic to know before I connect you?
Customer: I can't think of anything else.