Diagnostics & Tuning Powertrain Control Systems | Software | Troubleshooting

Rough idle when cold.

Old 11-11-2012, 10:46 AM
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Default Rough idle when cold.

I bought a 2006 Ram 1500 with the 5.7 Hemi and 125,000 miles.

When I start the truck in the mornings or when it's cold, it has an EXTREMELY rough idle. It will run rough until it warms up. I will then hear a CLICK and the engine will run smooth. I can drive the truck but it will vibrate like its going to fall apart.
I have taken it to two different mechanics and they have come up short. They say that cylinder one is misfiring but they don't know why. New plugs, swapped coil and they both think the injector is fine since it would run bad all the time if it was the injector.

So now I come to all of you in hopes that you can tell me what to try next. I have no clue where to start.

Thanks in advance for your time and help.
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Old 11-30-2012, 11:00 AM
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have you replaced the injector just in case? I mean, it logically makes sense that it would do it all the time if it were the injector, but cummon, we're talking about cars here... there is no such thing as logic.

I would try replacing the injector, or change said "bad" injector with one of the good ones, and see if the misfire follows the injector, or if it's still misfiring the same cylinder. if that's not the problem, then it would have to be computer related, to test and see if it is a computer related spark issue, you could test and see if it's getting any spark by pulling the plug wire when it's cold, if it snaps, then it's getting spark, if not, then you found the issue and I would assume the computer is having a glitch when running through the cold start cycle. at that point, i don't know what to tell ya, but at least you know you aren't getting spark on cold start, and that's something that a mechanic can go on.

hope that helps!

Last edited by Chally; 11-30-2012 at 11:04 AM.
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Old 09-15-2013, 11:47 PM
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Its been a while since I have updated this thread. I have not been driving the truck as much this summer. I got a company truck so the dodge was out of sight out of mind.

But I finally took off the intake manifold to get a better look at what was going on. Here is what I found.

All of the ports that lead to the valves are oily except the first one on the drivers side. I have added a couple of pictures so you can see what I am looking at. I honestly have no clue of which way it should look. But the code i was getting before said I was having a problem with cylinder #1. Now I can see it is different than the others. The first picture is Cylinder #1. The second picture is #3. Any suggestions, tips, or ideas?
Attached Thumbnails Rough idle when cold.-img_5721.jpg   Rough idle when cold.-img_5724.jpg  
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Old 09-25-2013, 07:02 AM
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Back to the drawing board!!!

I pulled the intake, cleaned it all up, replace all the spark plugs, replaced injector #1, put it all back together and the SAME thing continues to happen. AND IT GOT WORSE!!!!

Not to mention I got a red lighting bolt and loss of power!!!

I have code p0301 still showing up.

UGH SO FRUSTRATING!!

So here is what happened once I started it. It ran rough right of the bat. Threw a low fuel pressure code which cleared itself after I shut it down and started it back up. Initially, it ran rough and it smoothed out and ran great. Good throttle response and plenty of power.

So i let it sit overnight and started it the next afternoon. SAME THING HAPPENED. It started just fine and ran rough just like always. it Immediately threw the P0301 code. and just like always, once it got warmed up, it ran just fine. (I could feel it running a lot smoother now after it warms up, so that was a plus.)

But then something worse happened. I was driving along and the red lightning bolt started flashing and i had no power. If I stepped on the accelerator, it would just bog down. Erratic idle when stopped and even shut off on me. Once it shut off and I started it back on. the lightning bolt was gone and I made it home. I had this lightning bolt pop up before but only for a couple of seconds and then it went away.

So I am back at square one with more problems.

HELP!!!!!
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Old 12-10-2013, 05:08 PM
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I took the truck to the dealer. They told me the cam and lifters are probably the cause of my problem. Can someone explain to me why that would cause the problem on cold starts and then run great later?

$3800 is the estimate. How difficult is it to replace the cam and lifters if they are needed? Something I should tackle myself? I am pretty mechanical but don't have any special tools.
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