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Posted: 5/1/2021 11:17:01 AM EDT
[#1]
Best disable it anyway before you knock a damned ring land off.
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Posted: 5/1/2021 1:13:05 PM EDT
[#2]
Quote HistoryQuoted: Best disable it anyway before you knock a damned ring land off. That is the plan but something causes it, one of 2 million sensors I’m guessing? Don’t know, I got no engine service light yet |
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Posted: 5/3/2021 4:27:25 PM EDT
[#3]
It could be a DOD lifter has eaten a cam lobe.
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Posted: 5/3/2021 6:40:09 PM EDT
[#4]
It only does it when it switches from V4 to V8
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Posted: 5/3/2021 9:31:03 PM EDT
[#5]
Quote HistoryQuoted: It could be a DOD lifter has eaten a cam lobe. That's a good guess. If it has it probably killed the cam too. We run late model gm's in our fleet. I disable afm with a tuner as soon as we get new ones. I have 5 vehicles at or over 400k on the original engines now. Used to be dead at 200k burning oil and locking afm lifters around 200k before I started. |
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Posted: 5/7/2021 1:49:24 PM EDT
[#6]
Quote HistoryQuoted: It only does it when it switches from V4 to V8 |
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Posted: 5/7/2021 4:42:42 PM EDT
[#7]
Pardon my ignorance (not a troll post, I don’t own a late-model GM)...
They eat lifters/camshafts? Seriously? |
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Posted: 5/7/2021 7:09:36 PM EDT
[#8]
If it has a 6spd, put the gear selector in M and push the up arrow till it says M5. It will shift normally, but never go past 5th gear. This disables the AFM and will tell you if it is that or something else. I have a 6spd and this works. Not sure on other trans.
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Posted: 5/9/2021 2:52:14 AM EDT
[#9]
Quoted: If it has a 6spd, put the gear selector in M and push the up arrow till it says M5. It will shift normally, but never go past 5th gear. This disables the AFM and will tell you if it is that or something else. I have a 6spd and this works. Not sure on other trans. I will try that Quoted: Sure your not hearing spark knock? My truck used to do it often at 1500rpm or so under load (going up a hill without downshifting) That’s what I meant with detonation, I thought that’s what it was and filled it up with corn free premium gas and it made no difference I can’t hear any ticking at idle but driving if you turn the AC and radio down you can hear a tiny ticking, actually sounds like an exhaust leak but every exhaust leak I’ve ever had and not treated in time burned a hole fairly quick and this small ticking has been going a few months and it will go quiet when accelerating Also the knocking isn’t always made but if I work the gas peddle just right I can make it do it |
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Posted: 5/10/2021 9:57:22 AM EDT
[#10]
Both my 5.3 and 6.2 trucks have made an annoying ticking sound in the cab, even after GM says they 'fixed' the issue with a new high pressure fuel line.
It started with the noise coming in around the in and out of V4, then it turned into all the time. Dealer says it normal.  This might be what you're hearing. https://static.nhtsa.gov/odi/tsbs/2016/SB-10078755-7690.pdf |
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Posted: 5/10/2021 10:06:54 AM EDT
[#11]
Quote HistoryQuoted: Both my 5.3 and 6.2 trucks have made an annoying ticking sound in the cab, even after GM says they 'fixed' the issue with a new high pressure fuel line. It started with the noise coming in around the in and out of V4, then it turned into all the time. Dealer says it normal. This might be what you're hearing. https://static.nhtsa.gov/odi/tsbs/2016/SB-10078755-7690.pdf Ticking sound is very different from a detonation sound. Unless OP mis stated. |
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Posted: 5/25/2021 5:32:21 AM EDT
[#12]
Quote HistoryQuoted: Ticking sound is very different from a detonation sound. Unless OP mis stated. Clarification, there is a constant light ticking while driving that isn’t there at idle and the detonation/spark knock sound in switch from V4 to V8, I put the truck in L5 and drove about 40 miles, reset MPG as close as possible to exact start/stop locations and drove in normal shift, exact cruise control speed and gas mileage decreased .6 MPG in L5, why TF would you risk the lifter problems for trivial mileage gains? After driving some more in L5 I can make it “rattle” working the gas pedal but it’s very quick and hard to do. In normal shift V4 it’s guaranteed to rattle |
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Posted: 5/25/2021 6:50:05 PM EDT
[#13]
Quote HistoryQuoted: That's a good guess. If it has it probably killed the cam too. We run late model gm's in our fleet. I disable afm with a tuner as soon as we get new ones. I have 5 vehicles at or over 400k on the original engines now. Used to be dead at 200k burning oil and locking afm lifters around 200k before I started. Lucky they last 200K, I know at dealerships with ‘21’s stacking up like cord wood, hard to get parts for, plus GM had a bunch of defective lifters out in the parts supply chain. No way to ID them. |
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Posted: 5/26/2021 10:02:51 AM EDT
[#14]
Quote HistoryQuoted: Lucky they last 200K, I know at dealerships with ‘21’s stacking up like cord wood, hard to get parts for, plus GM had a bunch of defective lifters out in the parts supply chain. No way to ID them. Before the DOD bullshit they would, I pulled a 6.0 from an 03 Denali just shy of 400k for a square body waiting on a rebuild. It’s still sitting in my shop as the rebuild has been on hold for a room addition and a pool but the motor ran just fine, no fuel management curse ETA I’m looking for a good replacement ‘21 without DOD to trade on but Silverado’s seem to be in high demand and it’s either house payment level truck or the low level cheapo’s , I guess since the 21’s don’t have DOD everybody wants one? I’m too cheap to spend 60k on a vehicle |
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