BarryKH

I have found in my 60 years of shade tree mechanic work, that when I have an issue like you are describing, the very first thing I do is give the cable connectors and the battery terminals a very good cleaning. Although they look clean and you don't see any corrosion, there is a gray film that develops on them that causes that. Clean them with a wire brush, the battery and the cable ends, reconnect them good and snug, and I spray my with battery terminal protector I get from the auto parts, and it does a great job preventing this. When you can no longer see the red tint on the terminals, clean them again and respray with a light coat. I hope this helps. Many issues like yours are caused by clean looking terminals. Just my experience that I've had all these years.

I have not had this problem, but I would start by checking the axles, make sure the splines are not stripped. I would check everything I could like that before opening the differential. I seems as if the actuator motor is working, but I would be sure by having someone help me by having a hand on the actuator when you try to engage 4wd. I will try to do some research and see what I can come up with. Sorry I can't be more help.

I think I have finally fixed the quirky engine. I recently purchased an Xtool D7 Scan Tool. I did an idle relearn and reset the fuel/air ratios. Since doing this I have not had an incident that I called Quirks. Been a month to 6 weeks since I did it, refilled gas two or three times and no problem with starting after filling. I was grasping at straws, but couldn't stand to give up and let it go. It may not be fixed, but so far it seems to be.

I have cleaned the throttle body thoroughly, put a new cannister purge valve on, new fuel cap, ran full diagnostics with scan tool, no issues showing up.

2013 GMC Sierra SLE with 5.3 LC9. AFM programmed out. Sometimes when stopped at traffic light, or if left idling for a minute or two, when putting in drive it stumble and dies if you give it gas. If you let it idle in drive, it will take gas and go. Only happens at times when idling for a few minutes, then trying to take off. Besides that, runs great rest of the time. Bugs me that I can't figure it out. Anyone else had this issue?

Disconnect the battery and leave it for 30 minutes or so. Reconnect it and try to start it.

My grandson has a 2014 Ram that kept getting misfire code on a cylinder. All the fixes didn't fix it until I finally found through research that the PCM could be reset by going through a reset by using the ignition and a sequence of other things, i can't remember all of them, but I tried it and lo and behold it worked. I'm a GM man myself, but Chrysler Corp has them beat when it comes to resets and things of that nature. Of course the guy who posted this had a friend in the Dodge service dept.

You said the AFM boondoggle was deleted, which is great. I think the engine probably has an AFM delete kit which is new lifters, cam, valve springs, push rods, etc, which makes for a much, much better breathing engine. I would be very happy with it. You have 8 cylinders breathing air as they were meant to. Just my opinion since I have a 2013 GMC with the 5.3 LC9. It is programmed to not cut back to 4 cylinders, but it still isn't the air pump it's supposed to be. I reiterate that I believe you have a V8 engine doing what it's supposed to be doing.

I would look for something loose in a muffler or catalytic converter, or a loose clamp or bad seal in the exhaust system. The sound is not consistent enough, to me, to be a lifter tick. My grandson had a leak in his exhaust that sounded like a tick, but a clamp had worked loose and the gasket between the pipes was leaking. Just my thoughts from the experiences I've had. Sometimes I'm right, sometimes I'm wrong. But I have learned in my 74 years to do just what you're doing, ask others for advice from their experiences. Experience is worth more that all the books.

My grandson bought a 2006 Colorado LT1 crew cab 2wd z71 and only has one key and remote. The key is not chipped, but I was told to get the key part # by using the vin and they could help me with the keys I ordered and had cut not working. Do I have to go through a locksmith or dealer to get the part # for the key? Anyone else had a problem getting spare keys made that work? Thanks in advance.

I've noticed that going up or down hills if I let off the accelerator, the engine revs up to 1500 to 2000 rpm. I know the electronic throttle is position sensitive, but is it supposed to react to this? Is this a sign of a bad sensor, or normal? What is involved in converting it to a cable throttle, which is stable in any position of the vehicle.

I kept having fuel cap problems on my cadillac and it turned out to be the purge valve. I replaced it and haven't had any problems since. I think the purge valve could be sticking a little sometimes making it seem like a vacuum leak. I don't know, it never fails to start, just sometimes you hit the starter and it will spin over for several seconds before it starts. I have even suspected the accelerator pedal module, I'm just trying to figure it out without spending a bundle on parts I don't need. Sometimes, after idling for a minute or two, and you start to take off, it stumbles, and will die if I keep trying to give it gas, but will start right back up and run fine. If it stumbles and I just ease back off the gas and give it a few seconds it picks up and goes. It has me puzzled. I am far from a master mechanic and depend on advice from folks like you for help when I'm in over my head. Many thanks.

Does a failing Evap Purge Valve always throw a code. My 2013 Sierra sometimes cranks but won't start for a few seconds, DIC shows tighten fuel cap pretty often. I cleaned the fuel filler neck and installed a new cap, but still get the DIC message often. Sometimes if stopped for a minute or two at idle, it doesn't want to take gas and accelerate. Could the Purge Valve cause this without throwing an error code? No check engine light either.

I can't seem to find a replacement fuel filter for my GMC Sierra SLE LC9 5.3. GMparts says discontinued, but has a fuel filter kit. What gives? A Change?