Rough idle when cold.

[Solohopper]

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

When I start the truck in the mornings, 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 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.

 

[reefguy89]

any codes? i would think that if there is a misfire that it would throw a code. You said new plugs and coil what about wires?

 

[Solohopper]

Yes, the code is what told them that cylinder one is misfiring. They are just not able to pinpoint the cause. And it only when it's cold. :-( so with winter coming up, it's only going to get worse.

 

[mikes04hemi]

can you pinpoint the exact location "click" you are describing?

Since I own an 04, I am not up to speed about MDS systems and hopefully someone with knowledge about it will chime in. But I am wondering if there is a problem with your MDS and it is misfiring the cylinder?????

 

[Solohopper]

I cannot pinpoint the exact location. But it seems be coming from the top of the engine. The MDS may be an issue, Hopefully someone will chime in the has experienced this problem before.

 

[Solohopper]

So now that it's getting colder, this is happening more and more often. HELP!!!

 

[KGBIGCOUNTRY]

So you got a p0301 code? Thats gonna point to 3 diff things. 1) injector failure 2) spark failure (either coil pack or plugs) 3) broke spring or cracked ringland (not seeing that since you said it clears up once warm). If you are getting a p0301 code pull the front driver side plugs and take a look at them to see if they are fouled out any. Drive side cylinders are #1,#3,#5,#7 starting at the front of the motor working back towards the trans.. Pass side is #2,#,4,#6,#8 same order. Easy way to test the coil swap it with the front pass side to see if your code goes to a p0302. Hope that gets ya going bud.

 

[Solohopper]

The plugs in cylinder one were checked and changed previously to me getting the truck. I know this because its different than the other plugs. The coils were swapped and there was no difference. The injectors were ruled out because I was told it would always do it if there was an injector problem.
Someone mentioned the IAC. I was going to look at that next just to continue to rule things out.
This is getting worse. It has stalled on me a couple of times lately. And even started running rough after it warms up at times. :-(

 

[KGBIGCOUNTRY]

Find a shop that has a bore scope to check the ringland on the #1 cylinder. I reread your first post and sorry for not paying more attention to that and started on the last few. Did either of the shops check compression on that cylinder vs the others? Checking the ringland will make sure the piston is 100% there (#3 tends to be the failed one for some reason). Checking compression will give us info on the springs having any failure. Being an 06 springs are lesser on the list (03-04 had spring issues). Is the CEL still on to get a deff number code also for us?

 

[Solohopper]

One of the shops did a compression check on cylinder one. he said that there wasn't enough difference to consider it a problem. He was comfortable enough with the numbers to rule that out.

I will put the scope back on it tonight to see what codes are on it now.

Thanks!!!

 

[03MopaRamman]

Those Trucks got EGR? How cold we talking....I go into limpe mode at -10 F if I hammer the truck when its that cold until the TB warms a bit. What kenneth is telling you I would check. If it was dirty Injectors they would all be dirty and youd be getting a Multipule Misfire P300. PCV, MAP, And IAT should be changed with that knd of mileage......Guaranteed to Help. New Coil Boots and springs at $5 ea is always good and I would think about a new Timing Chain Before your bakelite breaks, hell stick a cam in while your there. Seriously though, Hope you do find the source of your Problem, Got my fingers crossed for ya and this is the best place to get the Outside of the Box Type Thinking....and we are Good at spending Money.

 

[Solohopper]

I hooked the scanner up again.

codes read.
P1521
P0300
P0301

I will try the PCV, MAP, And IAT if that will help.

 

[KGBIGCOUNTRY]

The 1521 is incorrect oil type, the 300 is random misfire, the 301 is front driverside misfire. Wonder if the click is the motor in the TB moving to another position after rereading the first post along with all the other info. Neither shop messed with the main harness behind the intake manifold correct?

 

[Solohopper]

As far as I know, neither shop messed with that harness at all.
Not really sure what the TB is.

 

[Hooker52]

TB is your Throttle Body

 

[Solohopper]

Okay, that is what I thought it was, but I wasn't sure what he meant by "moving to another position."

 

[KGBIGCOUNTRY]

The throttle blade along with the rest of the internals is what I was refering to.

 

[Solohopper]

I changed the EGR and it helped A LITTLE. doesnt run as rough or as long but it is still doing it.

I guess the PCV, MAP and IAT are next? What exactly is the IAT?

 

[KGBIGCOUNTRY]

Its the small sensor the hooks into your air intake tube. Should be a grey or black plug with a small sensor on it with a lill blue tip. Its held in pretty tight with a rubber gromet so becareful removing and installing the new one.

Here is a quick look at them
https://www.google.com/search?num=1....141.1328.1j10.11.0...0.0...1ac.1.4SfzyOUJN-0

 

[Solohopper]

Thanks!!!

I bought it last night but was unable to install it today. I'll be installing it in the AM.