I was drawn to this group through the mutual problem of DOD/AFM. My engine developed the lifter tick in an instant. It has not progressively gotten worse over time. My Tahoe has 260k miles and ran great until the P0304 #4 cyl misfire code. I had to take a crash course of sorts on the internet to understand the operation of the AFM/DOD system. I have a son that is a decent mechanic, and I tinker as well. I bought the Tahoe with high mileage ( I drive very little since retiring) and the intention if I started experiencing costly issues I would just find a salvage yard 100k mile replacement engine. Trying the lifter unsticking may buy me some time, but no guarantee it won't return. I think a proved running replacement engine might be the better gamble given the 260K. Murphy's Law always prevails with me, my luck would be new lifters, trays, VLOM, gaskets etc and then have another issue immediately after buttoning up. My oil pressure has dropped also, rarely hits 40, hovers around 25 or so. VLOM bolts loose. Makes me wonder if the screen on the VLOM is clogged, or the oil pick up tube o-ring is bad, sludge in the oil pan? I'm an old man, if I can get 50k miles from an engine now it would take quite a few years for me to drive them. I want the higher gas mileage of the DOD, was getting in the high 19's last long trip. I am retired and am not performance minded any longer. I also just want the best bang for the buck without alot of time wasting trial and error. In my area I can pick up a good engine for $12-1500. There has to be a point when you decide to just replace the engine. I have seen many that have more miles than me still going strong. There is nothing to say a replacement engine wouldn't develop the same issue eventually since it is a known fault. I haven't decided yet what approach to take. Maybe your responses will help me decide. Hats off to all the time and effort you have spent on these issues.
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This AFM/DOD delete project got put on the back burner. Yesterday was ready to start. Found out there was no spark. Grounded 7 pin coil bank connector black wire to firewall and it started. Before beginning this project ran fine except #4 lifter. Oil pressure was good on start up, brief run and was running very rough. Did a quick scan and saw reduced engine power, cam position sensor. Did not not run for more than 20 seconds or so. The ground for the coil was temporary and as the wire jiggled the engine would stop. Did I miss a ground on reassembly that was overlooked. I will look more today. The obvious ones are the one on the passenger side front of head (two wires, battery and one from loom) and the strap attached at firewall above brake booster. I will clean up those connections well today and add dielectric grease. Any other locations I should look at that may have been disturbed during the delete? Project was done in vehicle 2011 Tahoe 5.3.
I would try to free the lifter using the CPR tool first. I just did it on #4 of a 2008 suburban with 208000 miles on it. All it cost me was the price of the tool and a few hours of work.
It doesn't matter if it's continuous or not just that you make the required total degree of rotation. Most important thing though is to make sure you're using new bolts. I hear far too many people that try to reuse the old bolts and do that same torque method then snap the bolts off in the block.
I personally sometimes won't even use a torque angle meter or my fancy degree torque wrench. Sometimes I will just figure the 60° per point of a 6-point head and use that with a sharpie to do the math to get the correct angles. For example I believe that the harmonic balancer bolt is 120° which would be two points on a six-point head.
I haved torqued heads to spec, now comes the TTY "torque to yield" values. I'm old school and have never used TTY bolts. Idealy I would imagine if let's say 90 degrees is required first pass you could make one continuous 90 degree sweep. What if space would not allow (like cyclinders 7-8) a full sweep. Could you make two 45's to make the 90 since total movement is still 90 degrees? Does some scientific crap (bolt heats up while stretching and end value will be compromised if more than one effort is used to achieve the 90)come into play ? Or am I over thinking it? Using an angle guage of course. Goes without saying engine is still in vehicle.
Update, bought afm/dod delete and had pcm reprogrammed. Removed oil pan and cleaned and replaced with new pick up tube "O" ring. Winding down the project. Looked at several sources about disabling fuel and ignition to build initial oil pressure prior to starting. My engine compartment fuse block is missing the recommended relay to be unplugged,any advice? Everything worked as it should before the #4 lifter failure.
You are mostly correct in your observations/assumptions. Couple things to note though, torquing the VLOM down should be 16-17ft lbs. I've seen 18 strip out aluminum blocks. VLOM bolt tq won't effect oil pressure unless it was near the oil pressure sensor area. If oil pressure doesn't improve I have several videos, forum post, and even a copy paste thing I typed up on the matter. Just let me know if you need info on it. Going non AFM components can be required for several reasons beyond just a collapsed lifter situation. One could have a AFM lifter spin from a bad plastic guide, the roller/cam could get wiped out from pitting or gauling, you could even maybe find you low oil pressure situation is because of a bad second camshaft bearing and decide, "well, I'm already this far, f-it let's delete this trash." One more thing I'd like to note. The best way to check for a successful lifter release. After you are done tightening up the VLOM, use the starter relay to crank it over and watch the rocker. If the rocker works for at least 6-7 times in a row and not stopping till you stop cranking, you should be good to go. Just use this trick with caution or with ECM out. If you jump the wrong relay pins you could short out ECM.
I have seen the release trick last long over 50k miles, but I have also seen something else fail valvetrain related very soon after the release trick. As long as the release trick holds and done properly by disabling AFM though it is a long term fix. The release trick does require disabling the system though so any mileage gained from it will be gone. However the system doesn't get used over 55mph cruising speeds anyhow. So long term trips you really shouldn't loose any mileage. Also, just replacing a lifter isn't a option as it will likely fail again. This is of course if you don't saw the little oil pressure concern first. The reason these lifters fail is from lacking 26 PSI or higher oil pressure at the lifter during activation. If it doesn't have that much pressure while it activates the locks will bind and damage the AFM portion of the lifter. Considering the VLOM is loose and if the screen inside of it is plugged. In your position I certainly would not hesitate to do the lifter release trick. I did this message via cell phone while doing other things. If I missed anything please don't hesitate to ask again.