Podor

It almost sounds like there is still a passlock issue. We know fuel pressure is good. It may be helpful to put a noid light on an injector and a spark tester on at the same time and see what happens. I can't remember if the security system cuts fuel and fire or just fuel. If we are losing both at the same time, I would almost say the passlock is still an issue. It could be cam or crank signal dropping out, but that is almost never an issue on these, as far as I can tell. If I were still I a shop with a scope, I would probably watch cam and crank signals and see if they drop out. Not really a possibility in most cases.

Map sensors are used for monitoring only, they will not cause a no start condition unless it is shorted causing another sensor to lose 5v reference. Just for clarification; At what point did the no start condition start, what did you replace before and what did you replace afterwards? Mike Gmc has a good idea. Will it run above closed throttle? It is very possible that has to relearn idle if everything was so off. IAC motors will cause this also and not set a code. If it runs with a little throttle, we may be in pretty good shape. Keep it running until it gets a little warm, then let off and see what happens. It may take a little bit to relearn. If it runs but still won't idle, It's probably the IAC motor itself. The IAC motor allows a metered vacuum leak to control idle. If the motor itself is bad or the port is clogged, it won't be able to raise the idle on startup. So it will fire with the initial rich mixture controlled by the PCM, but if it can't raise the idle it will stall.

We have 2 potential issues that may or may not be related. The first issue is the high idle. The question is was that caused by a mechanical issue or an electronic issue. The 3 codes come from a higher idle condition that isn't controlled. If the TPS sensor sees closed throttle, but a high idle with matching MAF/Map signals, it flags the codes. That could have been caused by an open Pcv system or stuck open IAC valve. It could also be an electrical issue, but highly unlikely. Now we have the no start condition, which may or may not be caused by the repairs for the first issue. I suggest putting everything back, including the PCM and starting from scratch on the high idle issue first.

Does the security light flash? If you unplug the MAF sensor, does it run?

Here's my '05 Suburban Z71. I installed a GM Goodwrench LQ9 6.0 with Black Bear tune about 1200 miles ago. I would like to do a 2" leveling kit, but I have to recover financially from the engine first, lol.

It sounds like the IAC motor is not controlling the idle. GM vehicles usually don't set a code for IAC issues. The Idle Air Control motor is a stepper motor that controls air flow through a port in the throttle that controls the idle. The port may be clogged, the motor may be defective or there could be a wiring issue. There are probably 2 torx screws holding it in on the side of the throttle body. There is a cone shaped plunger with a spring on the back side. The motor pulls the cone away from it's seat to raise the idle by creating a controlled vacuum leak. Make sure there are no deposits on the cone an make sure the port is clean. If it looks OK or doesn't fix the issue, most likely the motor itself is bad. Super easy to replace, just make sure to hold on to the screws.

Is it throttle by wire or does it have an actual throttle cable?

I know there are probably tons of threads out there about the chevy shake. I had a '14 that I put 45k on and didn't have any vibration issue. I did do an alignment and rotate and balance at about 6k at an independent shop and found out that the toe was out about 2.5 degrees on both sides, which is a significant amount. I'm not sure if by fixing the alignment and keeping the tire wear down prevented the issue, or I was fortunate enough to get a good truck. I recommend having a shop other than the dealer with a road force balancer balance the tires and do an alignment. The dealer I bought my truck couldn't diagnose their way out of a paper bag. Is there any consistency in vehicles with the vibration, like tire and wheel combo, chassis length, 2 or 4 wheel drive? I haven't had mine for 2 years now so I don't remember much. It was a crew cab, 5.5 foot bed, 4x4 with stock z71 18' wheels.

I'm right there with ya.

From what I understand, the oil consumption issues are due to the rings seize on the AFM cylinders because of lack of maintenance and the conventional oil not holding up over time. GM switched to the Dexos full synthetic, lower viscosity and 8 qt + capacity to minimize the problems that the gen 4 5.3 had. My wife's '07 had the slugs replaced about 15k before we bought it. I run Valoline full synthetic and change the oil every 4500 to 5000 with no issues. I did disable the AFM. There is a TSB on the driver's side valve cover allowing oil to get sacked into the Pcv vacuum line. Ours smoked up the garage on cold startup before we changed it.

New guy here. I've been enjoying reading this post. I have owned a bunch of vehicles over the past 15 years for various reasons. My job required me to have a fairly new vehicle up until last year when they got us all company vehicles. In that timeframe, I had a '00 Suburban, '03 Silverado 1500, '11 Sierra crew cab with a Duramax and a '14 crew cab Silverado 1500, and my wife currently has a '07 Yukon XL. Now that I can have what I want, I traded my last truck in to get some cash out of it and go back to a Suburban, which was my favorite of the bunch. Here are the reasons I went back to the GMT800. 1. Interior. I know there's a lot of chunky looking plastic, but the layout is my favorite. Everything is easy to reach and easy to "feel" while driving so I can keep my eyes on the road. Even though the GMT900 is supposed to be an upgraded interior, both the high end dash in my wife's and the basic dash in the '11 were pretty flimsy. The seats fit me better. It feels more roomy than my wife's '07 not just up front, but everywhere, especially in the back. 2. Ride and handling. The '14 was by far the best driving of the bunch, but the GMT800 have been pretty close. My wife's has quite a bit of oversteer and not much feedback. I can easily load up the front end and corner well in my '05 compared to the '07 that's a little hard to predict. I actually think my Duramax handled better than our '07 (everything is tight and aligned with new quick struts). I also like the fact that almost everything in the suspension is greasable. My '00 Suburban had all OE parts when I got rid of it with 180k miles. 3. Power train. I'm not a fan of the DOD and VVT. My wife's had the slugs replaced right before we bought it, so I think we're good. I will concede that the Castech head issue can be bad. The heads on the newer 5.3 are far superior performance wise too. I love the 6.2 in the newer trucks too (Maybe that's pushing me towards the GMT900). I've had two of the 6L80s and neither seemed to do too well. I had a G8 GT in the mix and it shifted horribly until I had it tuned, and it still had some issues finding the right gear and sometimes it just wouldn't shift into reverse. The '14 Silverado was worse. Not to mention, I can get a nice 4L65E for way less than the 6 speed. 4. Styling. I prefer the body lines to the GMT900. I couldn't catch on to the fender flair profile on either version. Totally subjective. So, there you have it. Totally just my opinion. Either way, GM makes the best trucks, no matter what year!