Jerry Suiters

I had this motor built, it is a 5.3 LMG bored out to a 5.7 with forged rods and pistons, stock crank, TSP VVT cam .600 216/220 112 LSA with VVT disabled(I chose to disable after the fact) long tube headers and an air raid intake pipe and wix filter along with a ton of other supporting modifications. So I installed the motor over the last weekend and got it running, but its showing signs that the DOD/AFM system is active all the time, whether its in park, neutral, drive, reverse, or manual mode. I can tell because the spark plugs in the non DOD/AFM cylinders are clean and only the headers on the DOD/AFM cylinders have burnt off the paint. I am wondering why this is activating as I thought it only activated in "drive" over 50mph. Should I avoid running/driving the motor at all while this is happening? I am going to get it tuned shortly but planned on driving to the tuner. Any help is greatly appreciated, thanks!

68Formula

First, you shouldn't be running AFM and AFM lifters with a non-AFM cam period. The factory AFM cams have different lobe profiles on the AFM cylinders to compensate for the different lift. So when it's in 8 cylinder mode those cylinders will be filling differently.

Second, AFM lifters shouldn't be run much more than 0.500" lift and factory springs! Which is probably the problem. You have so much lift and spring force to match that lift, that it's forcing those lifters to collapse.

Do NOT even start your vehicle, until you get those lifters out of there. And while you're at it, you'll want to inspect the cam lobes to make sure you haven't damaged them. And if it's okay, since you aren't running the VVT anyway, sell your old cam (if not damaged) and buy a non-VVT cam. That cam should have a lot of advance dialed and without the cam retarding, it will quickly run out of breath on the top end.

Jerry Suiters

To clarify I have aftermarket non afm lifters that were recommended to me by the builder, its as if the ecu is just disabling ignition to the non afm cylinders

Edit: nevermind, those cylinders are getting spark, next i will check if they are getting fuel

Edit 2: just checked, the fuel injectors to non afm cylinders are not being activated