V10 warm idle problems
Newbie here. I usually am on the Ford forums. My dad recently bought another Dodge 2500 with V10. Excellent motor, first Dodge V10 we've had.
It is a 2001 2500 with 5-speed & 86K miles.
It has a bizarre (to me) idle issue. It started and idles great cold. Runs like a champ. Then when warmed up it will idle great for 5-10 minutes. Then it will start to idle a little rough. Then it will bog down to 200-300 RPM, choke and gage for 10 seconds then shoot back up to idle again. Initially it would shoot o2 sensor codes right when the idle recovered. After replacing o2 sensor codes it shoots a code for coil pack #2 (can't remember the code).
So long as I don't let it idle for extended periods of time it never shoots a code. Also you would never know anything was wrong unless you let it warm up and then idle for 5+ minutes. Just idling at a stoplight, etc it doesn't act up at all.
Have not had it very long. When we got it the thermostat was out and it was running cold all the time. Don't know if this could be part of the issue.
-replaced 2 upstream and 1 downstream o2 sensors (it had all kinds of o2 codes stored when we got it).
-replaced the thermostat (this was first thing done).
-pulled IAC and cleaned the valve and the port it inserts into. Also cleaned throttlebody.
I have run a bunch of searches here in the past couple weeks and couldn't find an answer. Hope I am not being dense.
Seen references to bad plenums - don't think the symptoms match up to that but could be wrong.
Thanks for your help!