Rough idle when cold.

[Solohopper]

I don't have experience with the 4.7, but with the hemi the PCM has two modes. When the engine is cold it runs in "open loop", meaning the fuel/ignition (AFR) is controlled by a internal table and the O2s has no input. When the engine reaches operating temp the mode changes to "close loop" with the O2s providing input (trim) to maintain the AFR to reflect this internal table that is constantly adapting to atmospheric and component changes (wear) within limits. If it is unable to adapt, then most often will generate a DTC. IMO, you do not have a cam/lifter problem.

What is DTC?

Any other ideas of what it may be if it's not the cam/lifter?

 

[hemihustlin]

Diagnostic trouble code aka "check engine light"

 

[dmancarp]

Holy crap, somebody with the exact same issue I'm having, even the same cylinder!!!! I've been told lifter and/or valve as well at $2G's+ but I'm having a hard time swallowing that. I have a 2008 5.7 and am ready to get rid of it because of this but i do love the truck.

Have you had any luck with this issue? I have a friend that will work on it for parts costs but am wondering if it's going to be worth it or should I just upgrade now. Thanks for any info

 

[Solohopper]

I have not done a thing with it. I don't drive the truck much anymore since I have a company truck. But at this point i can't really sell it for what I owe in the condition its in.

I was planning on doing all the work myself once the weather warmed up a bit. And I will probably just put all factory parts in it and leave it alone. I don't need to upgrade anything. K.I.S.S.

I'm "glad" to see someone else with the same problem. And def glad to hear the same explanation as to why. Makes me a bit more comfortable ordering the parts and getting to work on it now.

Let me know if you do it and the outcome. I'm sure everyone would like to know. I'll keep it updated if I do it as well.

 

[Gpadz]

On a 2003 to 2005 with a hemi 5.7. You need to replace the camshaft positioning sensor if you have idle/stalling/ or performance issues. It's a cheap easy fix. Make sure o2 sensors are good. And the mass air flow sensor is clean. That should help. The dealers can't figure these issues out.

 

[Redtruck-VA]

On a 2003 to 2005 with a hemi 5.7. You need to replace the camshaft positioning sensor if you have idle/stalling/ or performance issues. It's a cheap easy fix. Make sure o2 sensors are good. And the mass air flow sensor is clean. That should help. The dealers can't figure these issues out.

There are a multitude of things that can give a owner problems, cam and crank sensors being just some of them. Since we don't have a MAF it would not be one of them.
Welcome to the forum..

 

[mmasser]

I am also having a similar issue, my truck will idle rough and misfire until warm, truck runs fine after about 1.5 miles of driving. Dealer said it was throwing codes for cylinder #6 misfire. I replaced EGR and plugs, dealer tested coils said they are fine. Also replaced fuel injector with no change. Compression on #6 is good. Anyone have any ideas on what to look at next? This is starting to get expensive...

2006 Dodge ram 1500 with 5.7L Hemi

 

[Solohopper]

Since we have had two different dealers mention the lifter and cam. I would be confident to say that is the problem. I can't be 100%, but my guess is that is the problem. I don't have the time to deal with it just yet. So it will sit until this fall maybe. I just warm it up before I go. :-/

 

[Angler]

I have a 2006 Ram SLT with the 5.7 my truck does the same thing, when you start it it will misfire and run rough as soon as the truck reaches operating temp you can shut it off and start it back up and it runs fine. Then when you are driving down the road at a consistent speed then you let off the gas and get back on it it will misfire once or some times multiple times. When it starts acting like this if you let off gas completely for a 5-6 seconds and get back into it it will run fine. I have pulled the codes and it gives me a code of PO306 Misfire cyl6 and P0420 Catalyst System Efficiency Below Threshold (Bank 1)
I have had it to 3 shops and the Dodge Stealership and they all cant figure it out. Things I have done Replaced Coil packs, replaced plugs, replaced PCM, Replaced O2 sensors. I love the truck its in pristine condition other than this problem. The truck uses no oil between changes and does not smoke at all at any time.
Vehicle 2006 ram quad cab
Engine 5.7 Hemi
Miles 138,000
Mods Cat back exaust, KN Air Filter, Superchips tuner
Anyone Got any Ideas? Thanks in Advance

 

[Angler]

I have a 2006 Ram SLT with the 5.7 my truck does the same thing, when you start it it will misfire and run rough as soon as the truck reaches operating temp you can shut it off and start it back up and it runs fine. Then when you are driving down the road at a consistent speed then you let off the gas and get back on it it will misfire once or some times multiple times. When it starts acting like this if you let off gas completely for a 5-6 seconds and get back into it it will run fine. I have pulled the codes and it gives me a code of PO306 Misfire cyl6 and P0420 Catalyst System Efficiency Below Threshold (Bank 1)
I have had it to 3 shops and the Dodge Stealership and they all cant figure it out. Things I have done Replaced Coil packs, replaced plugs, replaced PCM, Replaced O2 sensors. I love the truck its in pristine condition other than this problem.
Vehicle 2006 ram quad cab
Engine 5.7 Hemi
Miles 138,000
Mods Cat back exaust, KN Air Filter, Superchips tuner
Anyone Got any Ideas? Thanks in Advance

 

[Angler]

OK well today I changed the EGR valve for no other reason other than it was easy to get to and something I had not done yet. While I was in there I removed the coilpack and the spark plugs from cyl 6 and swapped them out with cyl 1. I have already replaced the Plugs and coilpack but I am at end of rope. I was rewarded for my efforts with a cyl 6 misfire, rough idle when cold, and no changes. when I pulled out the plugs from cyl 6 they looked the same as the plugs in cyl one. I am also still getting the po420 code. through research I have found that the cat is probably bad due to the missfire but in no way will a bad cat cause a missfire so... can anyone help me out?

 

[Redtruck-VA]

Maybe this will help. The cylinder that is identified as misfiring is selected by the Cam sensor. The Cranks sensor identifies the engine is rotating and then combined with the cam sensor the spark, injectors and misfire DTC's are timed and identified. A misfire is nothing more than the engine suddenly changing speed outside an acceptable amount determined by the PCM. Maybe someone can correct me but I believe the DTC is not set until the engine has reached 160 degree's and is above 1600 rpm. I had a crank sensor go bad during a tuning session and had me all screwed up not knowing what was causing what. The engine would stumble when given a little gas.

 

[Angler]

Thanks Bro,
I will replace crank and cam sensor tomorrow

 

[Angler]

Well replaced the crank and cam sensor, disconnected the battery so system could relearn the sensors and guess what? No ******* change Still missfireing like **** on Cyl 6. Cliffs notes on my problem
Truck Misfires on cyl 6, Worse when it is cold. Driaveable after warm up but still random misfire.
Things I have replaced
CPU
COILPACk s
SPARK PLUGS
CRANK SENSOR
CAM SENSOR
EGR VALVE
O2 SENSORS

Anyone have any Ideas? I am a disabled Vet and can only put money in this a couple times a month when I get my check from VA I have had this POS to 3 shops including the dealership and have spent over 2000.00 in parts and labor and wasted a year of my life trying to get my truck to run right. Only to have the same ******* problem again and again.
Anyone know a shop near Tampa, FL that actually fixes cars?

 

[Redtruck-VA]

Brother I understand your frustration. It's tough throwing money at a shop and not getting anything fixed. Are you able to remove the Passenger side valve cover? I would check the #6 valve springs. The 08 model isn't known to have a valve spring problem, but if it was a 03/04 I would have said to check them early on. The misfire stays consistent in identifying #6 as the source. Did you replace the PCM with a rebuilt PCM that had the latest update? Did you replace all the coil packs or just one? If just one are you certain you or the shop has properly identified Cylinder #6? Passenger side, third cylinder from the front. Same with the injectors. Did you replaced them all or just #6? There can be an elusive grounding problem that can be helped by connecting an external ground wire from he PCM housing to the engine block/head to the Throttle body to the chassis ground found on the fender. Improper trans fluid level can cause an unstable idle for some unknown reason, but since yours keeps identifying #6 I think it is probably related to that cylinder. Compression test will tell if is normal (140-160) and within 10 psi of the other cylinders. Checking inj/coil wires of course need to be checked. I think on your 08 the wiring harness is one piece from the inj/coils to the PCM. So maybe a wire pinched or frayed from sometime in the past. Let us know what you find. Good luck..

 

[RonJon '06]

^^ The only thing I thought you could add to that list is the MDS solenoid (there are 4). I think its too much of a coincidence that it is cyl #6 that is the problem. MDS deactivates 1,4,6 and 7. The fact that it runs better after it is warmed could be that it is meeting the conditions where the MDS kicks in and #6 is supposed to be turned off. When it's cold it is supposed to be running on all 8 cylinders. I'm wondering if that's why the intake for cyl #1 looked so clean on Solohopper's 5.7 as well.

EDIT: Don't know what the deal is with the exclamation point ^, I didn't mean to put that there.

 

[RonJon '06]

I'm assuming you have MDS since it's an 06.

 

[Redtruck-VA]

^^^ good catch. I always forget about MDS.

 

[RonJon '06]

I'm glad I don't have to deal with it on my truck since it's set up like a 2500. IMO just one more thing to go haywire.

 

[Hookoil]

I have the same issue with my 06 Hemi. After changing the plugs, coil, upstream O2, crank and camshaft sensors, I am looking towards the lifters on cylinder 1. I pulled my valve covers off and noticed a lot of sludgy oil in there. I believe what is going on is the lifter is oil activated, basically 2 lifters in 1 from what I understand. I believe the oil holes in the lifter are plugged up. I put a pint of Marvel Mystery Oil in it and ran it last night. It ran GREAT! I believe the motor ran better then ever for my.(I bought the truck with this problem and it had 101K on it, It now has 104K) I will let you know how it runs this morning. I figured I would drive it to work today (100 miles round trip) and then change the oil in the AM. I will replace it with synthetic 5w-20. I hope this work as I really don't want to have to pull the lifters and replace them if I can avoid it. I also thought of trying Seafoam cleaner but I think Marvel Mystery Oil may be a little easier on the motor. We will see I guess. Has anyone actually fixed this problem. I have read a few forums on this same problem and its almost alway cylinder 1,7,4 or 6 which are the MDS cylinders. I have not heard of any sure fixes yet though.