Hello, I looked 2008 GMC Sierra 1500 that I was interested in purchasing with the 5.3L V8 has 174,000 miles. Truck runs rough at idle, rpms are fluctuating. Check engine light is on with codes P0300 and P0301. Can’t troubleshoot the problem. Coils, spark plugs, spark plug wires, new O2 sensors, new catalytic converters. Guy says that rockers all move so it isn’t Active Fuel Management lifters and he says 150 psi of compression across all 8 cylinders. Truck was at dealership, dealership says problem with cylinder numbers 1 and 8 the P0301 explains problem with cylinder 1 but why isn’t code P0308 being thrown? What else could be the problem?
Installed a 3" Motofab level on my truck last weekend. Rear is stock. Added 20x12s with 33x12.5 tires. Minor plastic and metal trimming, no rub at all.
Smoked my tails and 3rd brake light. Will smoke my front turn signals and corner markers this weekend.
Will also vinyl wrap the chrome mustache on the bumper, unless someone wants to trade for all black.
Going to do a muffler delete (leaving resonators) and clamp the flapper valve open, will also add a Range AFM delete.
Has 30% tint now, will eventually do 15% this summer.
Will post more pics as I make progress.
My 2012 Silver is one of the unfortunates to be cursed with AFM. It has 136k on it. It has gone through a quart of oil about every two weeks since I got it at 75k miles, plugs on 1, 4, 6 and 7 have to be changed about every 6 months (photos of #7 that got changed a few days ago because as usual, CLEARLY it was fouled and misfiring) and it DRINKS fuel. My average MPG's hovers around 10-11mpg..not to mention the horrible jolt it makes after cycling between 4 and 8 cylinders. Is there nothing I can do to, if nothing else, reduce the oil consumption?
My 2008 5.3L 4WD Avalanche with ~135K miles has recently been throwing a P0306 cylinder 6 misfire, along with a Stablitrak warning. It first happened a couple weeks ago but only lasted a day. I cleared the code and it was fine for another couple of weeks before it happened again today. It does go through a lot of oil (probably a at every 1,000 miles), and there is a clicking sound.
I know from researching this the last couple weeks that its likely failure of the #6 cylinder lifter and/or plug fouling due to the AFM system design and/or old PCV cover. I intend on doing some diagnostics this weekend including inspecting and replacing (if needed) plugs/wires/coils, doing compression tests, and pulling off valve covers to look for stuck lifters/valves.
My questions are:
1) Other than the obvious, is there anything else I should be specifically looking out for when running these tests?
2) Are there are any other diagnostic tests I should be doing while I am in there.
3) Assuming compression test is fine, and replacing plugs/wires stops the misfires, can I hold off on replacing a bad lifter if there is one?
4) I would plan on getting a Range tuner to disable AFM (which I should have done when I bought the truck 3 years ago) and replacing the valve coverwith the new one. If the compression test is OK suggesting there is (currently) no ring, gasket, valve, etc. damage, would these measures stave off more issues?
4) If a lifter is bad and I really need to replace it now, can I just replace the one, or do I need to replace them all? Also, how difficult is it to take the passenger side head off to access the #6 lifters?
5) If it does fail compression, am I likely screwed and looking at a rebuild or replacement?
6) Any other advice, recommendations, or thoughts?
Thanks in advance!
Hey guys I’m new to the forum but I’ve been a long time subscriber since I bought my 14 Sierra new in feb 2014. So I’ve read lots of horror stories on the site and I thought I’d tell you guys about my experience.
A few weeks ago over 5r holidays, my girlfriend and I were returning a uhaul after moving and she was following in my truck, she called to say that the check engine light was on and the truck had reduced power. We dropped off the uhaul and I hopped in and could tell it was misfiring and had a rough idle. I took it to my local mechanic and he told me cylinder 4 was misfiring and he tried a coil pack but that didn’t fix it, he did a compression test and it was holding compression but he told me this was gonna be a bigger problem.
luckily I still had powertrain warranty so I contacted the dealership that I bought the truck from and they had me tow it there using gm roadside. So my first hats off to gm, the lady I had on the phone from roadside assistance asked her manager to waive the tow fee as I was having it towed to my home dealership that was > than the 50 miles that they cover for free.
Once the truck made it to the dealership, it only took the. A couple of hours to figure out I had a failed lifter and broken rod for cylinder #4. Now I was freaking out because I’ve read horror stories on this site about having to argue with regional managers for warranty work this significant and I’ve heard dealerships arbitrarily saying work isn’t covered under warranty for whatever reason. Thankfully I can say my service advisor set me up with a rental the same day and reassured me that everything would be covered by gm. He did say parts were on backorder and it would take approx 2 weeks. Almost 2 weeks to the day, truck was ready to be picked up with 0 hassle the entire time.
This is my 3rd truck with the 5.3 and the only time I’ve had a significant mechanical issue. The truck only had 85000 km (around 50k miles) sure I was PO’d that my truck was out of commission for 2 weeks but I was extremely thankful that gm stood behind their product and was able to fix the truck for me. The truck seems to run fine now but I don’t know if I will keep it as I don’t know if it will be the same or if the issue will reoccur. I do know that my next truck will definite be another Chevy or Sierra. I can’t wait to see the reveal of the new Chevy this weekend at Detroit!
Jut thought I would post a positive warranty repair story and throw a kudos out to gm for making things right with me
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