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2008 chevy trailblazer_lt
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Discussion Starter #1
GOT MY 2008 TB BACK FROM THE DEALER. HAD BEEN GETTING A ROUGH IDLE MORE LIKE A STUMBLE WHEN SITTING AT A STOP. WENT THROUGH REPLACED PLUGS, NO CHANGE. I WOULD GET AN INTERMITTANT CODE FOR INSUFFICIENT SPARK ON THE #6 CYLINDER. I WENT OUT AND BOUGHT A NEW COIL AND PLACED IT ON THAT CYLINDER, NO CHANGE. WENT BACK AND SWAPPED NEW PLUGS AND THE COIL PACK TO A DIFFRENT CYLINDER, INCASE I HAD A BAD NEW PLUG OR THE COIL PACK. AGAIN NO CHANGE. BIG DROP OFF IN FUEL ECONOMY ALSO, AVERAGING AROUND 11MPG. BUT NO NOTICEABLE PERFORMANCE ISSUES EXCEPT FOR THE IDLE MENTIONED ABOVE.
WELL TOOK IT INTO THE DEALER, THEY COME BACK WITH THE #6 CYLINDER IS LOOSING COMPRESSION. WILL HAVE TO PUT A NEW HEAD ON THE MOTOR. THIS IS AT 59K MILES. IT WAS COVERED UNDER THE POWERTRAIN WARRANTY AND THERE IS SOME TYPE OF BULLETIN OUT THERE FROM GM. TOOK OVER A WEEK FOR THE HEAD TO COME IN. SO I'M ON MY FIRST TANK OF GAS, WAITING TO SEE WHERE THE MILLAGE COMES OUT AT.
BUT OBVIOUSLY THERE IS AN ISSUE WITH THIS MOTOR AND QUALITY CONTROL FROM G.M. IT WAS AN INTAKE MANIFOLD GASKET LAST YEAR AT 49K MILES, NOW THIS HEAD. THIS VEHICLE IS TURNING INTO THE WORST G.M TRUCK THAT I HAVE OWNED. PROBABLY THE LAST ONE TOO.:mad:
 

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2008 isuzu ascender
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975 Posts
engine

Usually the engine itself is very durable and many people will get 200000 or more out of them without too many problems.
 

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2007 chevy trailblazer_ls
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166 Posts
Did you clean, or ask the dealer about cleaning the throttle body. Did you buy the Trailblazer new ? Dirty throttle body will give that stumble or miss that you have. Dealer might not be that bright and just replacing things to make you happy.
These I6 motors seem to be really dependable. Sorry about your problems. All your problems have been Warranty Work correct ??

Check this link.

http://forums.trailvoy.com/showthread.php?t=51619&highlight=dirty+intake
 

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My 08 TB 4.2 L hit 180,000 miles and had the MAF sensor fail on the highway. Limp mode kicked in and I went to nearest parts house and replaced MAF. This part failed shortly after causing a P0300 multi cylinder misfire. I overlooked this as the problem for a while replacing mostly all sensors, throttle body, coil packs, plugs and VVT. I destroyed the throttle body cleaning it. I also made sure the intake bolts were tight. I had watched too many videos that had no fix for my problem. I had no idea what I was doing. I had to learn what the short and long term fuel trims were telling me along with the O2 sensors. Mine showed a rich condition. I did a compression test to verify the engine was not hurt and replaced all the injectors. I also verified fuel pressure was good. STFT and LTFT and O2 leveled out off the rich condition. I still had the P0300. Back to the beginning and replaced the MAF with an OEM GM part. I have a smooth idle now with average of 18.5 MPG and plenty of power.
 

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so all that because the maf wasn't ac delco, what brand that caused all the issues?
Well, Kind of sorta. I swapped a lot of sensors due to my lack of knowing what the problem was. The short and long term fuel trims and 02 sensor voltage pointed to leaky injectors. The failed parts house MAF sensor has a "Made in China 268" sticker on it. All in all, I saved a lot by doing the repairs myself. Even if I swapped a few parts that may or may not have been on the edge of failing. The long and short of it, it runs great now.
 
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