P0301 and 0300 Codes

[hatinthering]

2015 Tahoe, just turned 200K mi. Upon brisk downshift/accel, flashing CEL and traction came on. This happened once or twice over the last couple years, cleared itself shortly after and ran fine.
This time it didn’t clear itself. CEL still flashing while driving, clearly missing/running poorly. Scanned and got codes 0301 always, and 0300 with it about half the time. Checked cyl 1 spark, coil is good. Pulled plug (Original to my knowledge), looked like crap. Replaced, cleared codes, and ran perfect for 2-3 days.
Then back comes the flashing light and same codes, and rough running with clearly a cylinder offline. Cleaned nee plug and Replaced injectors this weekend, still no joy.
Any ideas beyond the dreaded lifter issue? Honestly does not seem like mechanical damage to me….no ticking, and cleared completely (and ran perfect, albeit for just a couple days) after the plug change.
Pretty stumped on this one….

 

[Fless]

Can you look at individual cylinder misfires to verify that it's hole #1, or another one? If one cylinder is misfiring, pull the rocker cover to see if the valves are moving.

Hang on to your old injectors; they're likely OE and may be okay. What brand and source are the replacements? Aftermarket parts are not very reliable these days, and there are some fake GM and AC Delco listings on eBay, Amazon, etc. Best to buy name brand from a brick and mortar store.

Can you put a good scanner on it and do a CASE (cam-crank correlation) relearn to rule it out?

What value is the MAF reporting at hot idle, in g/sec?

What do the fuel trims look like?

 

[OR VietVet]

What @Fless said and I an curious as to whether you bought new or from previous owner? You said has 200k miles and plug #1 looked original? Really? In the future please remember that some ignition components are maintenance items and are not supposed to be replaced just because having a problem. Especially the plugs. They should have been replaced 2 times already at 200k miles.

Yea, get a scanner hooked up and get some live data info and also check for a vacuum leak. Also like @Fless said, lots of crap parts out there.

 

[hatinthering]

Can you look at individual cylinder misfires to verify that it's hole #1, or another one? If one cylinder is misfiring, pull the rocker cover to see if the valves are moving.

Hang on to your old injectors; they're likely OE and may be okay. What brand and source are the replacements? Aftermarket parts are not very reliable these days, and there are some fake GM and AC Delco listings on eBay, Amazon, etc. Best to buy name brand from a brick and mortar store.

Can you put a good scanner on it and do a CASE (cam-crank correlation) relearn to rule it out?

What value is the MAF reporting at hot idle, in g/sec?

What do the fuel trims look like?

Definitely Cyl 1, I will pull the rocker cover next to check valve movement. Hundreds of misfires on Cyl 1 mode 6, zero misfires anywhere else.

Will do on holding onto the old ones, good point on possible fakes...I did buy "allegedly" GM on Amazon. Clearly though at least the other 7 new ones are working fine since replacement yesterday, but no change on Cyl 1.

I do not have CASE capability, but I can likely track someone down who does after I do the rocker check, assuming all valves are moving properly.

Will need to see if my scanner will read MAF and fuel trims as well, after I check for proper valve movement. Sounds like that is the next step for sure.

Regarding rocker check- I hadn't done this yet only because I nave never had the tell-tale ticking at all (very familiar with the noise from my 05 Z71, 380K mi), and because the condition went away completely for a couple days after the plug change. Is it possible/likely that a mechanical lifer issue could be intermittent like that early on?

Appreciate your reply, Thanks!

 

[hatinthering]

What @Fless said and I an curious as to whether you bought new or from previous owner? You said has 200k miles and plug #1 looked original? Really? In the future please remember that some ignition components are maintenance items and are not supposed to be replaced just because having a problem. Especially the plugs. They should have been replaced 2 times already at 200k miles.

Yea, get a scanner hooked up and get some live data info and also check for a vacuum leak. Also like @Fless said, lots of crap parts out there.

Thanks for the reply! This was bought used at about 90K maybe 4 yrs ago. Agreed on plug maintenance, that's on me...

Will get full capability scan after valve operation is checked under rocker cover...assuming they are moving properly. Sounds like that is the next step for sure. Fingers crossed...

 

[hatinthering]

Following up on this...I did remove the drivers side valve cover to check rockers. Zero movement on cyl 1 (not sure if it's intake or exhaust yet, doesn't much matter at this point, but it's the second lifter from the front). Never made a bit of noise...
Gonna start teardown this weekend, doing full DOD delete cam/lifters/etc...plan to keep this Tahoe for a while, in super shape other than this issue.
From all the vids I've watched, nothing looks terribly difficult...just tedious, time consuming, and awkward to reach things. Wish me luck!

 

[Maxentropy]

Please keep us posted. My '14 has 195k and I plan to do the same when the problem arises. Mine's very rusty but has nice a remanufactured 6L80 so I'd also like to keep it for the long haul.

 

[OR VietVet]

Following up on this...I did remove the drivers side valve cover to check rockers. Zero movement on cyl 1 (not sure if it's intake or exhaust yet, doesn't much matter at this point, but it's the second lifter from the front). Never made a bit of noise...
Gonna start teardown this weekend, doing full DOD delete cam/lifters/etc...plan to keep this Tahoe for a while, in super shape other than this issue.
From all the vids I've watched, nothing looks terribly difficult...just tedious, time consuming, and awkward to reach things. Wish me luck!

IMO, I would make sure you do lots of pictures. Maybe even refer from here to a build thread.

 

[2015TahoePPV]

Following up on this...I did remove the drivers side valve cover to check rockers. Zero movement on cyl 1 (not sure if it's intake or exhaust yet, doesn't much matter at this point, but it's the second lifter from the front). Never made a bit of noise...
Gonna start teardown this weekend, doing full DOD delete cam/lifters/etc...plan to keep this Tahoe for a while, in super shape other than this issue.
From all the vids I've watched, nothing looks terribly difficult...just tedious, time consuming, and awkward to reach things. Wish me luck!

Mine didn't make any noise either. I did get bitten by the counterfiet injectors from Ebay. If you paid less than $60 each for yours, they're likely fake.

Have fun on the swap!

 

[hatinthering]

Mine didn't make any noise either. I did get bitten by the counterfiet injectors from Ebay. If you paid less than $60 each for yours, they're likely fake.

Have fun on the swap!

Thanks, I'm not sure how fun it will be, but plenty do-able.
I did likely get fakes, but I did save the old GM ones...and all of the old and new injectors seem to be working just fine.
Pretty much half torn down at this point, UPS man just brought a big box of parts from BTR...will see about getting it done over the long weekend. Bought their full kit, stock-type DOD delete cam. Will post an update when completed

***Can anyone recommend a local tuner (SW FL/Naples/Ft Myers ideally) who does the DOD delete tuning? Would like to try to use somebody local before I mail it off...would prefer to just bring them the ECU

 

[2015TahoePPV]

Thanks, I'm not sure how fun it will be, but plenty do-able.
I did likely get fakes, but I did save the old GM ones...and all of the old and new injectors seem to be working just fine.
Pretty much half torn down at this point, UPS man just brought a big box of parts from BTR...will see about getting it done over the long weekend. Bought their full kit, stock-type DOD delete cam. Will post an update when completed

***Can anyone recommend a local tuner (SW FL/Naples/Ft Myers ideally) who does the DOD delete tuning? Would like to try to use somebody local before I mail it off...would prefer to just bring them the ECU

Mine seemed to run ok, but the fuel trims were rich enough on one side to kill my catalytic converter. I ended up with a bank 2 catalyst efficiency fault.

 

[hatinthering]

Mine seemed to run ok, but the fuel trims were rich enough on one side to kill my catalytic converter. I ended up with a bank 2 catalyst efficiency fault.

Thanks...I'll probably just reinstall my real GMs anyway...but will make a point to check fuel trims (along with all available data) right away when back up and running. Would like to see if I can squeeze another 150K or so miles out of this after the delete. Up to 380K on my '05 Z71...4 waterpumps, 2 alternators, 1 starter, and just 10K miles ago finally a trans rebuild...not too shabby! Never have had the motor open on that one...

 

[2015TahoePPV]

Thanks...I'll probably just reinstall my real GMs anyway...but will make a point to check fuel trims (along with all available data) right away when back up and running. Would like to see if I can squeeze another 150K or so miles out of this after the delete. Up to 380K on my '05 Z71...4 waterpumps, 2 alternators, 1 starter, and just 10K miles ago finally a trans rebuild...not too shabby! Never have had the motor open on that one...

I'm seriously considering one of those also. I think that's pretty much the epitome of GM reliability.

 

[hatinthering]

UPDATE. As expected, nothing about this has been overly complicated, but it is an extremely tedious and uncomfortable job with engine in. Already plenty of good step-by-step videos out there. 100% do-able, it just sucks...would be exponentially easier if I was 6'2", or GM had moved the engine location forward a few inches. Still about a full day away from being done...see why below. Heads back on, just intake, radiator, and accessories left to install.

#1 intake lifter was the only issue causing the problems...stuck collapsed. All rollers/cam/internals were perfectly clean, no wear shown at all... really the cleanest I've ever seen inside a 200K engine, surprisingly clean.

One big issue came up that added tons of work/time...the chain tensioner plastic guide snapped in half while compressing it to lock. This of course meant oil pan drop, oil pump removal, etc. Oil pan drop means xmember out, drop steering rack, on and on it goes...mercifully this is a 2WD, so I guess it coulda been worse. Easily added an extra 6+ hours to the job, as this is all on my back (no lift, just jackstands).

I did find a local tuner who can come to me, so I hope to wrap up assembly this weekend and have him come by with laptop first of the week...will update results.

If anyone has any specific questions about the process, feel free to ask and I'll offer what my experience was.

 

[hatinthering]

FINAL UPDATE. Got it all back together over the weekend, had to wait until Mon AM to get fresh oil/filter/coolant. Filled 'er all up, put fuel pump fuse back in, and did a few rounds of pedal-to-the-floor turning engine over to get the oil circulated. Took one last look around the engine bay, and fired it up. Started right away, oil pressure gauge good, and after a few seconds of idling was purring like a kitten. Let it warm a bit, and then a brief drive up and down the street, back in the driveway to check for leaks...none to be found, Went back out for a full warm up/cool down cycle, leak check, and another this morning...drove about 50 mi round trip. Still no leaks and running great, so calling this one done for now.

Overall thoughts in no particular order:
1. This job really sucked literally leaning over the engine bay for 4 days, but outside of that nothing was really challenging or difficult. One of the four days was "extra" dealing with the broken chain tensioner and necessary oil pan drop. Torque wrench, good breaker bar, harmonic puller, and something to hold the flywheel locked are must-haves. Nothing else very special, just turn nuts and bolts as specified...a whole lot of them.
2. I bought the DOD delete kit from BTR, along with a new front seal and water pump gaskets...it wasn't really clear, but the kit comes with new front seal and water pump gaskets...so I have extras of each, no biggie. Very happy with kit (standard stock type cam), everything seemed good quality and very complete, would recommend. All in the BTR kit, oil, coolant, etc. right at $1K in parts. Including the damn tensioner from local store.
3. Replacing the tensioner meant dropping the pan and removing oil pump. YMMV, but all of the fear about realigning the pump made no sense to me...I didn't see how a couple chunks of metal bolted to the block as "guides" were going to be any better than a few well-placed machine marks with a scratch awl to realign. Really there was next to zero play anyway, with the black plastic inserts in the holes anyhow. All working fine with oil pump/pressure.
4. The one advantage of removing the oil pump of course was ease of reinstalling the chain, Honestly not sure how easy it would have been to try to force it over the cam sprocket one link at a time like others have...but I didn't have to, so no real opinion there.
5. As far as the tune-out of AFM...still not done, I have just been driving in M5, which keeps out of V4 mode. Not going to drive much until the tune done, but very comfortable that I can just drive it to the tuner. Note- there is some info I've seen that disconnecting the electrical sensor on the brake booster will preclude V4 engaging...maybe that is true on the older LS versions, but it does NOT seem to be the case for LT engines, at least min 2015 5.3 L83.

Overall not much fun, but would likely do it myself again rather that paying $4-5K labor. Very happy with results though, and expect it will last quite a while now.

Happy to answer any questions if I can!

 

[Geotrash]

FINAL UPDATE. Got it all back together over the weekend, had to wait until Mon AM to get fresh oil/filter/coolant. Filled 'er all up, put fuel pump fuse back in, and did a few rounds of pedal-to-the-floor turning engine over to get the oil circulated. Took one last look around the engine bay, and fired it up. Started right away, oil pressure gauge good, and after a few seconds of idling was purring like a kitten. Let it warm a bit, and then a brief drive up and down the street, back in the driveway to check for leaks...none to be found, Went back out for a full warm up/cool down cycle, leak check, and another this morning...drove about 50 mi round trip. Still no leaks and running great, so calling this one done for now.

Overall thoughts in no particular order:
1. This job really sucked literally leaning over the engine bay for 4 days, but outside of that nothing was really challenging or difficult. One of the four days was "extra" dealing with the broken chain tensioner and necessary oil pan drop. Torque wrench, good breaker bar, harmonic puller, and something to hold the flywheel locked are must-haves. Nothing else very special, just turn nuts and bolts as specified...a whole lot of them.
2. I bought the DOD delete kit from BTR, along with a new front seal and water pump gaskets...it wasn't really clear, but the kit comes with new front seal and water pump gaskets...so I have extras of each, no biggie. Very happy with kit (standard stock type cam), everything seemed good quality and very complete, would recommend. All in the BTR kit, oil, coolant, etc. right at $1K in parts. Including the damn tensioner from local store.
3. Replacing the tensioner meant dropping the pan and removing oil pump. YMMV, but all of the fear about realigning the pump made no sense to me...I didn't see how a couple chunks of metal bolted to the block as "guides" were going to be any better than a few well-placed machine marks with a scratch awl to realign. Really there was next to zero play anyway, with the black plastic inserts in the holes anyhow. All working fine with oil pump/pressure.
4. The one advantage of removing the oil pump of course was ease of reinstalling the chain, Honestly not sure how easy it would have been to try to force it over the cam sprocket one link at a time like others have...but I didn't have to, so no real opinion there.
5. As far as the tune-out of AFM...still not done, I have just been driving in M5, which keeps out of V4 mode. Not going to drive much until the tune done, but very comfortable that I can just drive it to the tuner. Note- there is some info I've seen that disconnecting the electrical sensor on the brake booster will preclude V4 engaging...maybe that is true on the older LS versions, but it does NOT seem to be the case for LT engines, at least min 2015 5.3 L83.

Overall not much fun, but would likely do it myself again rather that paying $4-5K labor. Very happy with results though, and expect it will last quite a while now.

Happy to answer any questions if I can!

So glad you got it done successfully! You're now a member of the very elite 'been there/done that AFM delete club'.

 

[hatinthering]

So glad you got it done successfully! You're now a member of the very elite 'been there/done that AFM delete club'.

Thanks I appreciate that! I've been wrenching on my own cars for 35+ years now...so it wasn't too technically challenging, but I'm not as young as I used to be...sure glad it's done though!

 

[2017sltXL]

Thanks I appreciate that! I've been wrenching on my own cars for 35+ years now...so it wasn't too technically challenging, but I'm not as young as I used to be...sure glad it's done though!

Glad to hear you got it done. I'm kind of in that same boat as you, rarely take anything to the dealer but at the half century mark getting up and down on a creeper often gets old in a hurry.
One thing I found when I did my delete was that leaving the radiator out opened things up enough that I just stood in that space most of the time for things like cleaning the deck, torqueing the heads and balancer...whatever else made it easier I just stood right there in front of the engine.
Taking the inner liners out makes a WORLD of difference doing this job as well. I'm surprised more people don't just take the liners out, it's literally a five minute job per side once the tires are off and makes things so much easier for things like spark plugs, etc.
BTR kits are a great choice. I went with the Stage 1 cam, only draw back was the 4* lockout wedge was backordered for a week, but this is not my DD so not a huge deal.

 

[hatinthering]

Glad to hear you got it done. I'm kind of in that same boat as you, rarely take anything to the dealer but at the half century mark getting up and down on a creeper often gets old in a hurry.
One thing I found when I did my delete was that leaving the radiator out opened things up enough that I just stood in that space most of the time for things like cleaning the deck, torqueing the heads and balancer...whatever else made it easier I just stood right there in front of the engine.
Taking the inner liners out makes a WORLD of difference doing this job as well. I'm surprised more people don't just take the liners out, it's literally a five minute job per side once the tires are off and makes things so much easier for things like spark plugs, etc.
BTR kits are a great choice. I went with the Stage 1 cam, only draw back was the 4* lockout wedge was backordered for a week, but this is not my DD so not a huge deal.

Agreed with all! Especially the fender liners, which I should have mentioned in my writeup...I did remove the passenger side liner, and it does help quite a bit with access on that side. Takes no time at all to remove. Quite a few things can be done from that area when creative with various socket extensions, wobbles, etc.

Have had it completed for over a week now, driving 50+ miles a day, couldn't be happier with the results. All working perfectly. The soreness from the job has also worn off, so that helps quite a bit too...