H3 Oh no... cylinder 5 misfire!!!

[reaper]

This code came up today, and it just started idling VERY rough...

Hope it's not the head. Just read through H306's thread on that... yes, my VIN is in that range. I have 103,500 miles on it (early 06 model).

Is an official dealer diagnostic the first step, or is there a way to further diagnose it myself? If it's the head... is that something I can swap in myself?

 

[deserth3]

If your plugs are original, time for a change. Regardless pull the plug to see what shape it's in. As cheap as they are I'd change it. And don't get fancy, stay with OEM plugs.
If your plugs are good, Then swap coil with another cylinder to see if code follows coil.

Pretty sure next would be a leak down test. And call around. There are cheaper places than the dealer that can do a head change. Unless you can convince GM to warenty the head. Which I doubt on an early 06.

 

[cgalpha08]

Yep plugs and swap the coil to see if it might be that.

Sent from my DROID BIONIC using Tapatalk 2

 

[reaper]

By coil: do yOu mean the spark plug wire?

 

[reaper]

Disregard last post... Lol. Ok, stay tuned. Plugs are relatively new fwiw, gm plugs too.

 

[reaper]

Ok, pulled the coil... there is WATER in there (can't tell if it's coolant or just water... ) .. haven't pulled the plug yet. What does water in there mean? That probably means coolant is leaking through there and the thing is probably shot, doesn't it? Damn.

EDIT: Ok, I blew it out with an air compressor. Put the coil back on there and it seems to run real nice again. Will let it run for a while and will check it tomorrow. I did clean out the engine yesterday with engine cleaner and hosed it down with the car wash pressurized water... let's HOPE that's all it is but we'll know soon. Keeping my fingers crossed.

Sheesh, why does my hummer seem to be such a drama queen?

 

[deserth3]

Have you been through any heavy rain or car wash lately? I'd dry it out and see what happens.

 

[algin5109]

Just had same problem. Changed all the plugs,cleared codes and didn't go away. Was the head. She's at dealership right now getting fixed.

 

[reaper]

Just had same problem. Changed all the plugs,cleared codes and didn't go away. Was the head. She's at dealership right now getting fixed.

What was the cost?

 

[3Hummers]

High pressure water is never a good idea in an engine compartment. No one ever protects the electrical connections, alternator, etc well enough.

 

[algin5109]

They wanted $2990 total. But I called gm service and they helped me out slot. Price dropped to $960

 

[3rdH3]

There is a TSB on water intrusion coming through the fake hook vent and puddling on top of the coil packs causing misfires. When I had my 08 they were replaced under warranty.

 

[mkmcgreg]

There is a TSB on water intrusion coming through the fake hook vent and puddling on top of the coil packs causing misfires. When I had my 08 they were replaced under warranty.

I had this happen on mine.. I Let it dry out and everything was fine. I was having a general misfire code. Went thru a "puddle" a little too quick. I also think removing the stock air box is a factor as this leaves the coils more exposed. Hope it is just water causing ur issues

 

[reaper]

Ok, ill give it a few days. It sure smelled like antifreeze though...

 

[06 H3]

Damn dude...I would change the plugs then the coils. Thats what I did. They wanted $2400. I wouldnt accept that and you shouldnt either! Tell them its a known problem for 06's and ask them to do a GM goodwill for $1200. I got 1200 or 1400 I cant remember they said ok to that so quick I think if I asked them to do it for $800 they would have...Just throw em a low bid and have em goodwill it.

I would never ask for a GM to do their goodwill thing if this wasnt common but it is so I believe paying full price is bull

 

[reaper]

Happy Ending

So when this happened I was sure I was screwed... but after blowing it dry and driving it for a few weeks, I've had no problems. I pulled the coil and there's no fluid in there as well. So it seems to be all good!!!!

Moral of the story: don't clean the hummer. I had power steering fluid all over the place from a broken line... but yeah, should've avoided spraying down where the coils are. Those aren't waterproof it seems.

 

[mommibears]

Hi I have H3 2008 62,000 miles engine light came on and off, misfire2, changed coil, spark plug and injector, light off for now but still misfire, what can GM do for this? Mechanic said drive around for day n see if lights come back on or its the engine, does this sound right?

 

[Romeo]

Hi I have H3 2008 62,000 miles engine light came on and off, misfire2, changed coil, spark plug and injector, light off for now but still misfire, what can GM do for this? Mechanic said drive around for day n see if lights come back on or its the engine, does this sound right?

Check to make sure the spring inside the coil pack is not bent. I had the same issue and realized the spring was bent and nit touching the spark plug. Also , clear the code and drive it for at least 50 miles and check uf the CEL comes back on. Be sure to use OEM plugs from GM also.

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[Romeo]

There is a TSB on water intrusion coming through the fake hook vent and puddling on top of the coil packs causing misfires. When I had my 08 they were replaced under warranty.

I siliconed around the clips to keep the water out.

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[scoreh3]

Use a good electrical grease not silicone it will help with the electrical connection and help keep water out too. Use it on the connector and the spring where it contacts the spark plug .

 

[4speedfunk]

Aerosol silicone spray....I like a brand called "Wire Drier". Clean the spark plug wells...spray em down....install the plugs....spray the outside of coil pack boots...bolt em down...spray em again. Done.
The idea is to chase the moisture out of the plug wells...not to increase the conductance of the electrical connection.