2018 Randomly Stalls and No Start - No Codes!

[Kubs]

So if you have read my other thread I spent the last 10 months doing a number of "fixes" on my truck.  Its a 2018 5.3L with a BTR L86 DoD delete cam, LS7 lifters, rebuilt heads. new timing gear, chain, tensioner, oil pump, cam sensor, VVT solenoid, L86 intake and L86 throttle body.  I just got it back from the tuner on Friday where everything went well and the tuner actually commented on how well it runs.

 

On Sunday I was out making a couple short trips to various stores (might be important information).  Less than 5 min, run in the store, come out, start the truck and go to the next one.  On the 3rd stop, the truck stalled backing into a parking spot.  Went in the store came out and long cranked no start the first time.  Then fired up and I drove to the end of the parking lot waiting to pull out.  It stalled again and wouldnt start.  After a couple attempts it fired up and drove back home fine.  Zero codes this entire time.  I had my cheap Foxwell scanner with me and was checking live data on the way.  Timing looked good, fuel trims good, fuel pressure, etc.

 

Yesterday it did it again only it wouldnt start for about 15 min or more.  Would just crank sputter and immediately die.  Again watching the data, nothing seemed to be out of whack.  I tried the flood clear foot to the floor method and it would try to start more than with no throttle input but still die.  I dont know if it was the repeated attempts or just luck, but I held the throttle about half way and it fired right up and drove home fine.  I got back to my house, shut it off and it restarted no problem 5 times.

 

This whole time there are no codes!  The only sensor I didnt replace possibly related to starting and stalling is the crank position.  Does this sound like something an intermittent CKP sensor would do?  I would expect there to be a code with it though...  Any thoughts?

[Kubs]

I went ahead and replaced the crank sensor.  It was less than $30 and in stock at Summit by my house.

 

I need to borrow a scan tool from a friend local so I can do the relearn tonight, but it starts ok for now.  It did that before also though, until it didnt, lol.

[Kubs]

Friday I was able to do the relearn procedure.  No issues since then, so fingers crossed that was it!

[Kubs]

Small update.  It stalled a couple more times, but only after towing a trailer for about an hour.  And ONLY when backing up...  Still no codes.  Its been fine for almost 2 weeks since towing.  Im very confused...

 

It seems maybe its load induced, but then triggered by light throttle reversing.  Any ideas?

[diyer2]

With all the work on this truck it makes it hard to pinpoint a problem.

[asilverblazer]

I'd try talking to the tuner, to see what changes were made that might slow or eliminate detection of codes that would illuminate the MIL. Expect a canned response that assumes NO responsibility... so you would have to carefully exercise your tact to get a constructive discussion. 

 

Only other problem I've heard of or experienced that resulted in similar problems was the purge vent valve solenoid... or something along those lines on the 3.6l V6. This resulted in a crank no start condition BUT ONLY after fueling. I saw that on a 2014ish Buick Lacrosse AND a 2009 GMC Acadia. No codes on either of those. 

[newdude]

Battery cables ok?  This gen of truck 14-19 is notorious for either battery cables that aren't 100% seated and tight or have bad cables all together and can cause some weird things to happen.  

[Kubs]

On 10/1/2025 at 5:42 PM, asilverblazer said:

I'd try talking to the tuner, to see what changes were made that might slow or eliminate detection of codes that would illuminate the MIL. Expect a canned response that assumes NO responsibility... so you would have to carefully exercise your tact to get a constructive discussion. 

 

Only other problem I've heard of or experienced that resulted in similar problems was the purge vent valve solenoid... or something along those lines on the 3.6l V6. This resulted in a crank no start condition BUT ONLY after fueling. I saw that on a 2014ish Buick Lacrosse AND a 2009 GMC Acadia. No codes on either of those. 

 

Ok, we might be on to something here... I did get a P0446 a few weeks ago but cleared it and it hasnt come back.  I have a purge solenoid I ordered just sitting in the garage.  I will swap that.  But also I cant get it to stall right now, unless I load the car back in the trailer and go drive.

 

On 10/1/2025 at 11:18 PM, newdude said:

Battery cables ok?  This gen of truck 14-19 is notorious for either battery cables that aren't 100% seated and tight or have bad cables all together and can cause some weird things to happen.  

 

Yeah I checked and both are fully seated and not loose.  I had a similar thought as I did have the negative terminal off a lot recently during the engine work.

[davester]

Did you check/test that the cables themselves are working properly?

[Kubs]

On 10/5/2025 at 4:25 AM, davester said:

Did you check/test that the cables themselves are working properly?

 

Like a continuity test?  No I didnt.  But I would expect it to be more random than a very specific event making it stall if they were faulty.

[asilverblazer]

I had a car that would randomly be a no crank, no start - acting like a very bad battery. 

 

After an extensive amount of battery and starter swapping, finally managed to determine that it was actually a poor ground condition from the engine to the frame. A cheap ground cable fixed that. IT WAS INTERMITTENT. 

[davester]

I would suggest voltage drop tests.  Cables/connections can pass the continuity test a multimeter uses, because it uses a tiny amount of current to perform the test, but the much larger current needed when the truck is running, if the cable and/or some connection is bad, it's resistance goes up and it shows has having a voltage drop from end to end.

[TheRiver]

Check that notorious ground by the drivers side A-pillar.  There's been numerous threads here about it.  The ground does have a name, but I cannot remember it right now.

[doropallo]

On 10/7/2025 at 1:17 PM, TheRiver said:

Check that notorious ground by the drivers side A-pillar.  There's been numerous threads here about it.  The ground does have a name, but I cannot remember it right now.

G218 ground issues. It's been discussed here too or just Google it. 

Another thought is the knock sensors, they set the timing. They caused stalling on my 2001, and of course it was the one under the intake manifold. 

[Kubs]

Just to close this out, it ended up being the charcoal canister.  I got a P0446 code and replaced the vent valve and purge solenoid.  The truck stopped stalling but code would come back every couple weeks.  I replaced the charcoal canister and its been golden.