$350 for a throttle body clean??? I would suggest you tell them it will cost you less to have it towed somehwere that will be HONEST with you and clean the throttle body than it will for them to do it. Common business practice, don't let the customer leave without paying something out of their pocket to help offset them doing the warranty work.
The throttle body has 4 bolts and takes 5 minutes to come off, 5 minutes to clean, and 5 minutes to put back on.

 

Fuel injector cleaning is accomplished by using a bottle of Chevron Techron in one full tank of gas. Cost= $10
Fuel Additives


Throttle body cleaning is simply removing the throttle body and spraying in down thoroughly with a can of throttle body cleaner which costs less than $5. It does involve some labor, but as has been stated already the $350 they are quoting you is highway robbery. Tell them NO to that work.

 

Can u update me on what is going on with your H3. Mine was in the shop for a week, they replaced cylinder head because of #2. I picked it up drove it less than 10 miles, steering wheel visibly shaking because engine running so rough, reved up the engine while in park then again in neutral and oh yeah guess what...."popping/misfiring". Drive it back to the dealer and there it is AGAIN.

 

Prone to what problem???

"The head issue", the one and only one that caused warranty extension, involved only L52 motors built before March 31. 2006. Those heads did not have properly hardened valve seats. EVERYTHING since does.

Can an Atlas motor (I4 through I6) have a valve-train or head/head gasket failure issues? Hell yes, but to assume they are all related is like ...... grassy knoll and Pearl Harbor conspiracy theories.

A cracked or broken valve spring, broken spring retainer, improper valve assembly or lash adjustment, blown head gasket, bad coil on ignition pack, bad connection to a coil pack, bad spark plug, cam position sensor failure, and VVT PCM mapping errors can all cause misfires.

 

Funny then you can explain why so many of the later ones have the exact same issue at low mileage counts even though the seats were supposedly improved? The problem is not limited to 06's. The problem is simply bigger than what they thought it was and alot more than they want to take care of or admit to.
As a master tech for 12 years I can tell you very few vehicles come in with valve train failures at 17k. Or 35k or 75k. High mileage motors, sure they can dump a seat or break a spring at higher revs no problem.
Next you'll tell me there is no design flaw with the radiator too I suppose?

 

Then you know what "the problem" was....?

The valve seats of the intake valves deteriorated and allowed some exhaust gasses to travel back out the intake valve, causing a misfire condition. GM issued a recall to replace the cylinder heads on models with this specific problem and changed the manufacturing process of the all Atlas heads, effective April 1, 2006.

What happens on forums is people have an issue, they come here and to others, look around and say..... Gee, my CEL went off, and it was for a misfire, so I must have the problem too? Take it to the dealer, and it gets fixed..... a lot/most of these folk are clueless as to what was fixed or what caused their specific issue. When I say "fixed" .... to be defined later.

You also know that these motors are a PITA to work on internally and require specialized tools?

4.2L, 3.5L and 3.7L
Head bolts break, usually right at the block deck, usually easy to remove, but requires head removal, which leads to tearing down the front of the engine becasue the tool designed to hold the chian slips out and the chain drops into the pan. Now requires removal of the oil pan, which is a pain in the *** and basiaclly requires engine removal.

Head bolts are also know to break upon reinstallation as well, usually if the proper proceedure isn't followed ( oiled threads and base of bolt head, proper torqueing sequence, and proceedure, they are torque to yeild bolts, and CANNOT be reused ). What's the chances of this being ignored?

If you are using an OBD2 engine management system, at some point you can find miss fire codes due to weak valve springs resulting in poor seat sealing. Not anything to do with the seat itself, but still a misfire.

Early versions also had issue with intake gaskets and the composite intake leaking. This has gotten better, but still happens occasionally = misfire.

Lord know pleanty of head gaskets have coughed it up on these as well = misfire.

These motors use dual over head camshafts, the exhasut cam timing gear hydrualically adjusts exhaust cam timing, (VVT for EGR effect: retards cam to allow some spent gasses to remain in cylinders to cool the next firing cycle; & performance) not too problematic, but you need the the right programming to make it work, a brain fart here and ..... misfire.

Now to the "fix" part. GM's cost analysis and dealer whining caused these repairs to be tackled by component replacement, rather than an actual repair work. IMHO because of a plethora of **** poor under qualified mechanics who apparently are no longer capable of making a diagnosis and repair, but can read a scan tool and follow the tech bulletins to do what some maintenance engineer says should be done.... whether you need it or not. So, you get this code = replace with a fully assembled head and gasket.

I personally have seen 4 with a weak valve spring (one was cracked, two had a small pieces missing, one was just "soft" so I assume it was cracked, but could not see one) another with a shot retainer, and another one that the spring was broke so bad or long that the valve had wobbled enough that its valve seal was ob longed and leaking. Only one of those actually needed the head replaced.
Yet, all of these were head replacements? Why, because apparently we do not want to replace just 5 $3.56 springs anymore, it is better to pay monkeys to replace the entire $1100 head unit and call it fixed..... and they still don't get it write every time?

Sure blows when they replace the head only to find out the PCM had a flash corruption after its all done.

So talusfan, you can have your design flaw conspiracy theory, but I look at it as corporate ineptitude.

 

Actually they replace the head as an assembly because neither the dealer or techs are machinists who can spec every part of the head and valvetrain and it cannot be sent out if it is a warranty job or be milled if needed. Out of warranty then yes they can replace whatever without gm in the middle but they don't because
A. heads cost more, higher profit margin, quicker turnaround time.
B. it's extremely difficult for even a good service writer to get a customer sold on 50.00 in parts and 1000.00 in labor.

The problem with techs these days is that technology has far exceeded the average monkeys knowledge base without a 4 year degree. Who wants to go to college for 4 years and rack up 35k in loans and invest 40k in tools just to make 18-20 an hour?
So I agree there are alot of monkeys out there who can only replace parts. A good diagnostic tech is a rare find.

and I don't really think weak springs or bad seats at low mileage constitutes a conspiracy theory, more like an engineer somewhere who needs a kick in the nutz for being stupid.

 

I also just had a code with cylinder 5 misfire on my 06 H3. I have 47k miles on her. I took it to the dealer. They checked the coil pack, spark pugs, and sensors. Nothing cleared the code out. So they clean the throttle body and fuel injectors. After cleaning the code cleared right off. I have since drove it 400 miles and haven't had a problem. I notice that the ideal is a little smoother. The dealer only charged me for the cleaning and I only payed $125.

 

any specifics as to what year for the trailblazer, the coils are expensive, need to save a little.

 

I was getting an occasional #5 misfire code. Changed the plugs with Champions (7981) and replaced the boots - made the problem worse. Changed back AC Plugs (41-103), but problem was a bad coil pack - not cheap. Everything is good now.