I have an '07 H3.

Check Engine Light illumintaed today. Computer says "Cylinder 1 Misfire".

Wondering if anyone has had a similiar issue and what the fix was....

Thanks!

 

plug? coil?, control?

the book says misfires can damage cat conv,,rich mix?

 

Check the spark plug hole for water (primarily on 08 and newer but a slim chance if could happen on a 07; especially if late build). There was a problem with water entering and remaining in that spark plug hole; causing some problems.

If not, switch ignition coils between cylinder, if that doesn't work switch plugs. If the code goes with the plug or ignition coil, that is the culprit.

Also, when re-installing the coil, make sure to put some dielectric grease on the rubber boot that goes over the plug insulator. DO NOT put dielectric on the actual contact in the boot or on the plug. Dielectric grease is non-conductive and can cause connectivity problems, but is good to prevent a spark jump from the boot to the engine.

Also, run a few cans of Techron through the fuel system to make sure the injector is clean.

If that doesn't work, might want a dealer to check fuel pressure, but that usually leads to a random misfire code P0300.

Here's the bulletin on the water...


#09-06-04-025: Malfunction Indicator Lamp (MIL) Illuminated, DTCs P0300-P0306, Engine Runs Rough (Inspect for Water Intrusion in Spark Plug Recess Area, Replace Spark Plug and Ignition Coil, Seal Ign Coil Bolt Hole) - (May 12, 2009)


Subject: Malfunction Indicator Lamp (MIL) Illuminated, DTCs P0300-P0306, Engine Runs Rough (Inspect for Water Intrusion in Spark Plug Recess Area, Replace Spark Plug and Ignition Coil, Seal Ignition Coil Bolt Hole Vents and Seal Hood Air Grille)


Models: 2008-2009 Chevrolet Colorado, TrailBlazer

2008-2009 GMC Canyon, Envoy

2008-2009 HUMMER H3, H3T

2008-2009 Saab 9-7X

All Equipped With Engine RPOs LLR, LLV, LL8

Please Refer to GMVIS




--------------------------------------------------------------------------------

Condition
Some customers may comment that the malfunction indicator lamp (MIL) is illuminated.

Some customers may also comment that the engine runs rough.

The technician may find DTCs P0300, P0301, P0302, P0303, P0304, P0305, or P0306 set as current or in history, depending on which engine the vehicle is equipped with.

Upon further examination, the technician may observe evidence of water intrusion into the spark plug recess area.

Cause
This condition may be caused by an engine being exposed to a large quantity of water, which may result in some of the water seeping down past the vented threads of an ignition coil bolt, then flowing through the vent opening that is located in the bottom of the related ignition coil bolt hole, and collecting in the spark plug recess area.

Correction
Important: DO NOT reprogram or replace the engine control module (ECM) for this condition. If evidence of water intrusion in the spark plug recess area/s is not observed, then refer to the appropriate DTC procedures in SI.

Observe the Misfire Current Counters parameter with a scan tool, in order to determine the affected cylinder(s).
Remove the air cleaner resonator and outlet duct. Refer to Air Cleaner Resonator and Outlet Duct Replacement in SI.
Disconnect the engine wiring harness electrical connectors from the affected ignition coil(s). Refer to Ignition Coil Replacement in SI.
Remove the ignition coil bolt(s) and ignition coil(s) from the camshaft cover. Refer to Ignition Coil Replacement in SI.
Note: If water is observed in ANY of the spark plug recess areas, then it will be necessary to apply Loctite® 565 PST Thread Sealant* to ALL of the ignition coil bolt hole vents and bolt threads.

Inspect for water intrusion in the spark plug recess areas.
Warning: Wear safety glasses when using compressed air, as flying dirt particles may cause eye injury.

If any water is present, then remove the water from the spark plug recess areas with low pressure air.
Remove the affected spark plug(s) from the cylinder head. Refer to Spark Plug Replacement in SI.
Replace ONLY the affected spark plug(s) with new spark plug(s) as needed into the cylinder head. Refer to Spark Plug Replacement in SI.



Fill the bottom of the ignition coil bolt hole vent with Loctite® 565 PST Thread Sealant* as indicated in the illustration, and apply it to the ignition coil bolt threads also.
Replace ONLY the affected ignition coil(s) with new ignition coil(s) as needed. Refer to Ignition Coil Replacement in SI.
Connect the engine wiring harness electrical connectors to the ignition coil(s). Refer to Ignition Coil Replacement in SI.
Replace the air cleaner resonator and outlet duct. Refer to Air Cleaner Resonator and Outlet Duct Replacement in SI.
Clear the DTCs with a scan tool.
Hood Grille Modification Required for HUMMER Vehicles Only
Remove the hood air grille. Refer to Hood Air Grille Replacement (H3) or Hood Air Grille Replacement (H3T) in SI.



Secure 3M™ Strip Calk®, P/N 051135* around the outside perimeter of the integral retention clip (1) opening in the vehicle hood (all 4 sides of the rectangular slot).
Repeat this procedure for the remaining slots.
Install the hood air grille. Verify that it fits tightly against the hood. Refer to Hood Air Grille Replacement (H3) or Hood Air Grille Replacement (H3T) in SI.



Advise the customer to use care when washing the hood on the HUMMER vehicles. Extreme water pressure should not be directly applied to the edges of the hood air grille.
*We believe this source and their products to be reliable. There may be additional manufacturers of such products/materials. General Motors does not endorse, indicate any preference for, or assume any responsibility for the products or material from this firm or for any such items that may be available from other sources.

Parts Information
Part Number
Description
Material Allowance

12629472
COIL, IGN
--

12625058
SPARK PLUG (IRIDIUM)
--

051135 or Equivalent
3M™ Strip Calk® - 08578 Black

18.3 M (20 yds) Box
US $1.00

(18 in)

CAD $1.50

(0.46 M)


Warranty Information (excluding Saab U.S. Models)
For vehicles repaired under warranty, use:

Labor Operation
Description
Labor Time

J7929*
Ignition Coil and Spark Plug Replacement / Seal Ignition Coil Bolt Hole Vent
0.5 hr

Add
For Each Additional Cylinder
0.2 hr

Add
Seal Hood Air Grille
0.3 hr

*This is a unique labor operation for bulletin use only. It will not be published in the Labor Time Guide.


Warranty Information (Saab U.S. Models)
For vehicles repaired under warranty, use:

Labor Operation
Description
Failed Object
Fault/Reason Code
Location Code
Warranty Type
Repair/Action Code
Labor Time

3411105**
Ignition Coil and Spark Plug Replacement / Seal Ignition Coil Bolt Hole Vent
34111
16
0
01
01
0.5 hr*

*Add 0.2 hr for each additional cylinder using.99 time/OLH.

 

I had the same issue over a month ago and since I was still into my drivetrain warranty I took it to a dealership. They said that prior to them doing anything a throttle body cleanse would be needed. After that they would "jump" coils to see if it had a bad one. I was informed by forum users not to have too much concern with it throwing the code once and to save my money by not paying for a throttle body flush. Instead I was told to use Techron fuel system cleaner. No code thrown as of yet.

 

ok, sounds good - my 07 still has the 100,000 warranty - hopefully it'll cover the repair.

 

whew!!
i never wooda thunk it

 

A random misfire code P0300 is a bastard code. It will set for many things, including unbalanced rotors and a few other odd reasons. My advice on a P0300 is clear it or wait till it goes away. If it continues to appear, add some injector cleaner, preferably Techron, and start burning good fuel. Yes, there is a major difference between fuels, in the amount of detergent they add.

I had the RMC and I burned Kroger fuel. After two cans of Techron and only burning Chevron fuel for a few weeks, the code has never returned. (Chevron created Techron and uses it as an additive in their fuel. Texaco is owned by Chevron, and they have the additive.)

Here's a good site for some information on fuel...

http://www.toptiergas.com/

As for the more specific codes (P0301-P0308), then tend to lead toward a more specific problem such as a bad injector, bad plug, bad coil, or mechanical problems with that specific cylinder. But the first thing to do is clear it and see if it continues to reappear.

I will note that the throttle body cleaning for a specific code is usually (I say usually) not the problem. More related to the RMC than a cylinder specific code. Reasoning is that a dirty throttle body will affect all cylinders equally.

 

I had a "Cylinder 1 Misfire" code, so I'm assuming that would be P0301. Does anyone know if the Hummer GM 100,000 factory warranty will cover this?

 

All depends on what is setting the code. Dirty fuel or clogged injector might not be covered, failed coil, or injector might be covered. In addition, a lot depends on your dealer.

 

UPDATE:

Well, it's still @ the dealership service, and they're waiting on GM to call back and decide if they'll pay for it.

I'm now being told that a few of the cylinders are misfiring and that it keeps changing on which ones are misfiring.

Error code PO300 they say.

They recommend a fuel injector flush and cleaning the throttle body which would run $144 without the warranty paying for it.

They're waiting on GM to decide. If they decide NOT to pay, is it hard to clean the throttle body and fuel injectors? Would that issue cause several cylinders to misfire?

Thx!