Misfire at Idle

[napalmsticks]

Hello! First thread on this forum, might as well make it good I guess. Sorry for the wall of text in advance.

I have noted a rough idle for the past year on my truck when coming to a stop and while sitting still at idle. Also while "creeping" for lack of better terms (Foot off the skinny pedal at 1 - 2 MPH) it also seems to idle pretty rough at times. I started my truck this morning and after 20 minutes at idle waiting for the wife, all that are married know what I'm talking about, I jumped in and noticed my CEL came on at some point during the idle. Upon hooking up the code reader I figured out it is a misfire on #4 (P0304). I put our trip on hold and began looking into what could be causing the CEL knowing in the back of my mind my 2006 H3 is well under the PI VIN range for the soft valve seats and currently at 71,000 miles. After cleaning the MAF, cleaning the TB, installing a new coil pack, swapping the plugs, checking the intake manifold bolts and checking every vacuum line I could to no avail I finally proceeded to warm up the engine to check compression and complete a leak down check at 100PSI. The numbers I got are:

Compression Check:
#1 - 185 PSI
#2 - 172 PSI
#3 - 165 PSI
#4 - 170 PSI
#5 - 183 PSI

Leak Down Check:
#1 - 76 PSI
#2 - 75 PSI
#3 - 55 PSI (Couldn't get the valves to seat for some reason, rocked the crank under pressure and they wouldn't seat)
#4 - 68 PSI
#5 - 77 PSI

During the leak down check I noted a decent amount of air coming from the intake valves on all cylinders. With the compression and leak down numbers on #3 I am very surprised I wasn't getting a misfire on #3 also. CEL is still on for the misfire on #4 and I am at the point where I assume my head will need to be replaced. I plan to do it myself as I doubt GM will cover it even with my mileage. My reason for posting at the moment is to ask two questions. Has anyone recently had GM cover a head replacement for this problem under warranty and is there a write-up on replacing the head on this engine anywhere? I have the necessary factory service manuals and it looks similar to other head replacements and motor builds I have done in the past, but with every engine there seems to be an easy way to complete the these tasks.

 

[Cyouincourt007]

Welcome, hopefully some feedback coming up.

 

[poweraidon]

Im in the same boat as you right now. I have a leaking intake valve so I'm just gonna replace the whole head since my 3 is closing 100k. I've read on other post if you still have warranty GM will replace it.


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[napalmsticks]

Sucks, are you planning to do the head yourself? Are you seeing the same indicators that I have? The warranty for GM in 2006 was 5 year / 100,000 miles with an extension for Colorado' s in the VIN range for head problem to the seven year mark right? I'm not sure that any of the early head issues will be covered at this late in the game. I assume if you call and complain to GM enough they might help with the labor or something. The way I look at it is the head replacement would be around 800 to 1000 for me to do it myself. Even with GM helping on the bill I doubt they would come close.

 

[poweraidon]

Sucks, are you planning to do the head yourself? Are you seeing the same indicators that I have? The warranty for GM in 2006 was 5 year / 100,000 miles with an extension for Colorado' s in the VIN range for head problem to the seven year mark right? I'm not sure that any of the early head issues will be covered at this late in the game. I assume if you call and complain to GM enough they might help with the labor or something. The way I look at it is the head replacement would be around 800 to 1000 for me to do it myself. Even with GM helping on the bill I doubt they would come close.

I'm having it done at a shop. When he did the compression test cylinder 2 was had 30% less than all the others. He's still researching on the best/cheapest head to get. So I'll let you know which one he orders. But you should definitely try to call GM it doesn't hurt to try. I know they've had numerous complaints about the head problem on earlier 06 models.


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[napalmsticks]

I'm having it done at a shop. When he did the compression test cylinder 2 was had 30% less than all the others. He's still researching on the best/cheapest head to get. So I'll let you know which one he orders. But you should definitely try to call GM it doesn't hurt to try. I know they've had numerous complaints about the head problem on earlier 06 models.


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I have been looking at the remanufactured heads, GM part number 19168846. I am definitely calling GM to complain, they put out a substandard product and published a PI on it.

 

[Graham2990]

I had a misfire on my 2008 about 2 months after I got it. P0303. Misfired hard to the point that you'd hear it 5 feet away from the vehicle.

Read through the site and tried new plugs, throttle body clean, MAF Clean, Seafoam'ing the upper end and fuel, all to no avail. The truck ran noticeably smoother afterwords, as I'm sure the prior owner did none of that in 75K, but it still had a misfire.

The fix was a bottle of Tectron additive. Read about it on another post here and figured that for $10 I'd give it a try. Poured it in at the parking lot of the auto parts store and by the time I'd made it the five miles home the truck idled smooth as could be.

Blamed it on bad fuel.

Obviously yours falls in the 06 bad head range, but it may be worth trying the simplest/cheapest fix first.

 

[napalmsticks]

I had a misfire on my 2008 about 2 months after I got it. P0303. Misfired hard to the point that you'd hear it 5 feet away from the vehicle.

Read through the site and tried new plugs, throttle body clean, MAF Clean, Seafoam'ing the upper end and fuel, all to no avail. The truck ran noticeably smoother afterwords, as I'm sure the prior owner did none of that in 75K, but it still had a misfire.

The fix was a bottle of Tectron additive. Read about it on another post here and figured that for $10 I'd give it a try. Poured it in at the parking lot of the auto parts store and by the time I'd made it the five miles home the truck idled smooth as could be.

Blamed it on bad fuel.

Obviously yours falls in the 06 bad head range, but it may be worth trying the simplest/cheapest fix first.

Now that is a great idea, not sure why I didn't think about that! :thumbs:

Techron:

Seafoam:

Not too smokey.

Profit?

The CEL is off now due to me not letting the truck idle for very long. I am going to give it the week to work through the tank full of Techron and let it idle for an extended period at the end of the week. Thanks for the good ideas Graham!
:cheers:

 

[poweraidon]

Haha yeah I just put a bottle of techron in too let's see how it turns out


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[Graham2990]

Glad I could help. Can't take credit for the Techtron as I came across that in another posting on this site.

Prior to my H3 I owned an I5 Colorado. The upper end seafoam trick was common place in the Colorado circles.

Did it to my Colorado the first time with about 100K. Went down a 3 mile road and after a U turn I was driving through my own smoke on the way back.

My H3 wasn't near as bad but my prior experience has really sold me on the seafoam.

 

[napalmsticks]

After installing my Scangauge yesterday I noticed I have a P0300 stored without my CEL being on. :roll: Not sure if it was active or pending.

 

[poweraidon]

My cel still came on. My mechanic is ordering a oem head from GM. He said those ones on ebay were bad.


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[napalmsticks]

My cel still came on. My mechanic is ordering a oem head from GM. He said those ones on ebay were bad.


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Just say no to Ebay heads!

 

[napalmsticks]

Misfire is back again. This time #2 cylinder. Replaced all coil packs not too long ago. Pretty sure it's the head...:roll:

 

[Romeo]

My CEL went on this morning with a P0303 (cylinder 3 misfire) I cleared the code ; hopefully it doesn't come back.


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[napalmsticks]

I called GM and they opened a ticket for me. Going to the dealer on Friday for the Blower Motor recall and head diagnosis. I am going to try and have GM eat some of the costs if it is the head. Wish me luck!:cheers:

 

[napalmsticks]

Well I guess that is that...

 

[Bigunit]

Well that sucks! Sorry to hear. What are your options at this point? Any luck having GM pickup part of the cost?

 

[napalmsticks]

The dealership said they might be able to help me out, the current estimate is $2,600. I am kinda pissed that GM said I had to go to the dealership to get it checked out before they would even deal with me. I paid $350 to have it troubleshot and GM said I am not in warranty and they cannot help. I don't understand why I had to pay the dealership $350 for GM to figure that out? Currently sitting at 87,000 miles. GM hasn't been a big help so far:

I brought up the PIP and said it was a factory defect - No dice.
Brought up that Colorado had there warranty extended to 100,000 miles because of the head - No dice.

My numbers for the #3 cylinder match the report, I think I lost #2 between my initial leak down test and now. It looks like I might be doing the replacement myself.

 

[alrock]

Let us know what happens.

 

[H322]

Seafoam:

What is the proper steps and how many cans to run sea foam through the motor? Have been wanting to do this just kind of hesitant never done it before. Thanks


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[JonBishop]

I did that, there's a YouTube video ( http://youtu.be/V7fv-Fg1hKU )on a I5 Colorado and he takes you step by step through it, it really does make a difference in my opinion but try it out
The only thing I didn't do was add it to the crack case, I didn't see any need too, and just make sure you don't drown the hoes in the liquid so you don't hydro lock your engine

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[napalmsticks]

Ordering all the stuff to replace my cylinder head. Any write up with helpful tips? I have the FSM and this:

http://www.autozone.com/repairguide...Components/Cylinder-Head/_/P-0996b43f81b3c7f2

Being that the thermostat is a PITA to replace I assume it would be worth replacing it while i'm in there. Any other suggestions?

Parts List so far:

http://www.gmpartspros.net/oe-gm/19168846
http://www.gmpartspros.net/oe-gm/88984219
http://www.rockauto.com/en/parts/fel-pro,ES71334,cylinder+head+bolt,5308
http://www.freedomracing.com/lower-timing-gear-retainer-en-48464-alt.html
http://www.freedomracing.com/camshaft-holding-tool-j-44221.html

 

[4speedfunk]

V8 time.

 

[napalmsticks]

V8 time.

LOL, I am with ya! I really want to take the plunge but we have crazy emissions here, an active CEL will cause me to fail emissions and the safety inspection. I saw 06H3 completed the swap but I cannot find a definite list of the required parts and walk through of the swap (I will have to look through his thread again). I think he is in Cali so I assume if I did the same swap I should pass. I found a 2007 3.7 for $2,350 but without a VIN from a 2007 Colorado or H3 they said there will be no warranty, I assume it would be the same for a V8. Not too sure I want to replace my current engine with a known history for a used engine with unknown history.