Archived Won't Idle down

[cgreek]

I have a 2005 Dodge Cummings 3500. While driving along the road the engine would not idle down when I stopped at a stop light. It will not idle under 800rpm.
This is my first post so I hope I gave enough information Cgreek

 

[cerberusiam]

Not really enough info to say much of anything. Need to know transmission, mods, updates, codes, etc to really guess at anything.

If it is a manual does it do it all the time?

If it is an auto trans how about when putting it in neutral or park?

 

[cgreek]

Sorry It is an automatic transmission and the rpms ae the same whether in park or neutral. I have no updates or mods and i have yet to by a reader for the codes..my first problem with the truck..other than that all i can say is it is a 4xe 3500 long bed swr

 

[cerberusiam]

With a 2005 you can do the key on-off 3 times and the codes will come up in the odo window if any exist. Did the problem just start out of the blue or was it at the dealer for anything where it might have gotten flashed?

Have you checked for water in the fuel? Do you run a fuel additive?

 

[cgreek]

Bought a reader yesterday and found not error codes. Started it this morning and it ran ok? But I read 750 rpms yesterday when it seemed to run to fast and today it is at 750 but is running ok. So I put a cleaner in the fuel tank and a new fuel filter and will see if the problem come back. Have not seen any water in the tank or when I drain the fuel pump. I am puzzled about the RPMs because with the problem it slammed into gear as if it was at least 1500rpm Thanks for you responce

 

[cerberusiam]

Wait a minute, you are all over the place here with symptoms. Either it was idling at 800 rpms and jumping to 1500 rpms or it wasn't, you cannot assume rpms from feel.

Now knowing it is an auto, and you said it seemed to slam into gear, did it also try to push thru the brakes when stopped? If you see a jump in rpms and wanting to push thru the brakes it should not do that in park or neutral. Symptoms like this point directly at the TQ converter in the transmission. Remember, we cannot see or feel what you do, you have to be specific on rpms, symptoms, etc, or you will not get correct advice.

 

[cgreek]

TQ is a good thought. I was not sure what it normally idled was until the next day when it worked ok. So I was confused also, for it was the same as when it had the problem. The problem again: I had to hold the brake hard at a stop to keep from going forward.
But to have it run ok the next day after sitting all night could lead to TQ but how can you get more driving power from the some 750 rpm. Not sure what in the TQ would cause such a bazaar problem. Does this help

 

[cerberusiam]

Yeah, that is a typical symptom of the TC failing. There is a sprag clutch on the stator that is supposed to release when wheel speed goes under 30-35 mph, this is par of what generates the stall on a TC. When it doesn't release you have a no-stall TC, along with pulling thru the brakes the truck is likely a dog until you get speeds up over 30 mph or so then it feels and shifts fine. There are other things that can cause the same problems but not as common as the TC starting to fail. Time to upgrade to a good billet cover lower stall TC to harness the ISB TQ.