Hello all,

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.

I have
-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!

 

Plenum is not an issue on the V10, totally different manifold. There was an issue with crossfire on early V10s, but it was fixed with the '99 model year. Still, if a PO changed wires and did not follow the factory wiring positions you might have the issue. Running cold is normal for these trucks. The cooling system is overbuilt for everything but towing.

 

Check for crossfire as the prior poster said. Search for TSB 18-16-98. As stated by Miami_Son, this shouldn't be a problem past '97, but that's no guarantee that the PO didn't mis-wire it. The TSB shows the correct wire routing.
In addition to cleaning the throttle body and IAC, did you check to ensure the IAC is working properly?

 

Thanks for taking the time to reply to a newbie, fellas.

I will check out the potential crossfire issue, thanks for giving the number to lookup.

To follow up. Yesterday I had to drive it a couple hours. On the way home there seemed to be an odd miss or hesitation.

It occurred when going down hills and the throttle is just slightly on (it has no cruise so I know how much throttle it was getting). Going up hills it ran great (throttle opened wider). I also got a code for TPS voltage (P0121) along with some more O2 codes ().

Anyway it seems to have more issues. I may go ahead and replace IAC but it seems there may be another gremlin lurking. I think the crossfire could explain the issue - I opened the hood in the dark when I got home in the dark and couldn't see spark jumping anywhere but will do the reading previously suggested.

Thanks for any help you can throw my way!.