Engine stalling, rough idle, rpm fluctuation.

[rdezs]

I'm far from perfectionist due to lack of skill, but that sounds like something I would do. I do wonder how mine stacks up? How many miles on your truck? There are 156K on mine. I don't have a vacuum gauge...yet!

I had wondered about the PCV valve since NBS LS had them but NNBS don't. Any chance that orifice can get blocked/plugged?

I've got a 2014 Escalade with an AFM deleted 6.2. kept the VVT by using an oem L9H camshaft. 176,000 miles, runs like new. Then there's the 2003 Hummer H2 with the LQ4 6.0, currently just over 114,000 miles. Also runs like new. Neither use any oil. The 6.2 with the AFM delete has a Melling 10296 oil pump that comes with the +10 psi overstock spring installed. Steel plugs tapped into the towers under the valley cover. Oil pressure relief valve in the oil pan removed and replaced with a stainless steel bolt with a copper washer. Have the heads gone through by a local guy that works on NASCAR heads for a living. About 32 psi hot idle, 1700 RPM it's 55 PSI. It went from 17.5 MPG on the highway cruising 65 to 21.7 MPG.

Same oil pump on the 6.0, 36 PSI at hot idle and 60 PSI at 1700 RPM. It does hit about 70 PSI at 3,000 RPM and up.

Then an hour open bow 19 ft boat, I'm running a 6.0 bored to a 6.2, with a Holley sniper EFI bolted down to an aluminum intake manifold. Only has a stage one cam, and it's way more power than the boat needs. You can go fast enough in choppy water to scare yourself, LOL.

Currently building another 6.0 bored to a 6.2. Not getting too crazy, aiming for a streetable 500 horse power. Went for a 58x reluctor.... In the market for a 2010 to 2014 Sierra four-wheel drive pickup with a blown motor.

 

[Fless]

I'm far from perfectionist due to lack of skill, but that sounds like something I would do. I do wonder how mine stacks up? How many miles on your truck? There are 156K on mine. I don't have a vacuum gauge...yet!

I had wondered about the PCV valve since NBS LS had them but NNBS don't. Any chance that orifice can get blocked/plugged?

Not all the NBS engines had a physical PCV valve; my '04 L59 doesn't, and I don't think any of the '05s and '06es had them.

 

[donjetman]

I had wondered about the PCV valve since NBS LS had them but NNBS don't. Any chance that orifice can get blocked/plugged?

Here is a GM TSB that applies to your vehicle: https://static.nhtsa.gov/odi/tsbs/2014/MC-10114272-9999.pdf
has it been accomplished? if not, then yes the driver side valve cover which is the dirty suction side of the pcv system, can become clogged.
Ask me how I know

 

[OBSandaNNBS]

I've got a 2014 Escalade with an AFM deleted 6.2. kept the VVT by using an oem L9H camshaft. 176,000 miles, runs like new. Then there's the 2003 Hummer H2 with the LQ4 6.0, currently just over 114,000 miles. Also runs like new. Neither use any oil. The 6.2 with the AFM delete has a Melling 10296 oil pump that comes with the +10 psi overstock spring installed. Steel plugs tapped into the towers under the valley cover. Oil pressure relief valve in the oil pan removed and replaced with a stainless steel bolt with a copper washer. Have the heads gone through by a local guy that works on NASCAR heads for a living. About 32 psi hot idle, 1700 RPM it's 55 PSI. It went from 17.5 MPG on the highway cruising 65 to 21.7 MPG.

Same oil pump on the 6.0, 36 PSI at hot idle and 60 PSI at 1700 RPM. It does hit about 70 PSI at 3,000 RPM and up.

Then an hour open bow 19 ft boat, I'm running a 6.0 bored to a 6.2, with a Holley sniper EFI bolted down to an aluminum intake manifold. Only has a stage one cam, and it's way more power than the boat needs. You can go fast enough in choppy water to scare yourself, LOL.

Currently building another 6.0 bored to a 6.2. Not getting too crazy, aiming for a streetable 500 horse power. Went for a 58x reluctor.... In the market for a 2010 to 2014 Sierra four-wheel drive pickup with a blown motor.

Nice rides, that H2 sounds like a real sweetie.
For when I measure mine, any reason the larger engines would pull more vacuum? I wouldn't think so but also don't know.

That seems like a lot of oil pressure to me, but obviously you have a reason. Care to enlighten me?

PS you're right about that boat, but then again I just can't bring myself to leave perfectly good dry land to get on a boat. LOL.

 

[OBSandaNNBS]

Here is a GM TSB that applies to your vehicle: https://static.nhtsa.gov/odi/tsbs/2014/MC-10114272-9999.pdf
has it been accomplished? if not, then yes the driver side valve cover which is the dirty suction side of the pcv system, can become clogged.
Ask me how I know
View attachment 457303
View attachment 457304

Ah, that's gold, sir, thanks.
I'm having a little trouble determining if the valve cover applies to me. I have a 2012, which could have been produced after October 2011. I don't know how to find a build date, but coolant hoses have 05122012 printed on them.
LMG btw.

Yikes that's a crusty plug!
The difference in your covers is wild!

 

[rdezs]

Look on the label with the RPO codes, VIN, etc. one of them will have the month and year of production. (Which really is the date it was submitted for production, actual production can be weeks later.)

 

[rdezs]

Nice rides, that H2 sounds like a real sweetie.
For when I measure mine, any reason the larger engines would pull more vacuum? I wouldn't think so but also don't know.

That seems like a lot of oil pressure to me, but obviously you have a reason. Care to enlighten me?

PS you're right about that boat, but then again I just can't bring myself to leave perfectly good dry land to get on a boat. LOL.

I like a little bit more vacuum than stock, as I do a lot of short trips. Plus it doesn't hurt anyway to have better crankcase ventilation. Any blow by will very based on engine condition, miles, etc. I don't think any of the lS engines, per se, have any more blow by than other ones. (4.8/5.3/6/6.2 and so on)

I like to have decent oil pressure. The 10296 pump is both higher volume and higher pressure than OEM. Considering your oil does quite a bit to keep your bearings cool, I figure it can only help in the long run.

 

[OBSandaNNBS]

Look on the label with the RPO codes, VIN, etc. one of them will have the month and year of production. (Which really is the date it was submitted for production, actual production can be weeks later.)

I promise I checked before posting. The build date of 05/12 was on the door sticker. I just missed it.

Thanks for your replies, I'm learning quite a bit of sage wisdom.

I want to replace the filler tube assembly, but I CANNOT find the filler tube oring. The one that sits in the valve cover. The tube is not sold with it for the LS. It is for the 350. Maddening.
I can't even locate a part number.

 

[rdezs]

Pretty much any auto parts store will have an o-ring behind the counter. Might take your old one with you as well as the new tube.

 

[rdezs]

Maybe this one on Amazon that comes with the o-ring?

Engine Oil Filler Tube Fit https://a.co/d/4zOsNzT

 

[OBSandaNNBS]

Maybe this one on Amazon that comes with the o-ring?

Engine Oil Filler Tube Fit https://a.co/d/4zOsNzT

I think that's the PN for the OBS tube. I'm just going to get a generic oring once the tube comes in. I really wanted it to be blue appreciate it!

 

[OBSandaNNBS]

Hey @abdullah_Zahra did you get any further on this issue?

 

[OBSandaNNBS]

If you want to go overboard and be a perfectionist.... I actually have an LS filler cap that I drilled and tapped threads to mount a 4AN fitting. Then I have a 4AN female to a vacuum line hose barb and connect it to my vacuum gauge to check crankcase vacuum at idle and at 2,000 RPM. I like to see about 7 inches of vacuum at idle, which usually nets me about 4 inches at 2,000 RPM, and down around 1 to 2 at full throttle. If you can achieve that, you'll insure no oil leaks from an overpressurized crankcase.

So how do you fine tune it? The newer revised valve covers for LS engines have no PCV valve, but rather a very small orifice. Over 100,000 miles it's normal to have some more blow-by than the new engine.... Removing the valve cover and increasing the size of the orifice with the next size up drill bit, will increase the crankcase vacuum a bit.

Hey @rdezs,
I've done research to no avail. Do I have to take the valve cover off to clean the orifice? Or can I shoot some carb cleaner into the place where the PCV line connects to the cover?

Right now I'm going for a cleaning, if I have to step it up after chasing other possibilities, I will.

Thanks!

 

[rdezs]

I would do it with the valve cover removed. If the orifice is plugged you likely have a lot of carbon you'll want to clean out anyway.

 

[atvmxr]

chasing down the rough idle on my newish to me 09 Tahoe. Is there a way to tell if that TSB for the valve cover has been swapped out? I presume its the drivers side cover since the tsb mentioned cylinders 1&7?

 

[opfor2]

chasing down the rough idle on my newish to me 09 Tahoe. Is there a way to tell if that TSB for the valve cover has been swapped out? I presume its the drivers side cover since the tsb mentioned cylinders 1&7?

Unfortunately no you will have to remove it inorder to check.

 

[donjetman]

chasing down the rough idle on my newish to me 09 Tahoe. Is there a way to tell if that TSB for the valve cover has been swapped out? I presume its the drivers side cover since the tsb mentioned cylinders 1&7?

square hole in the new cover, round hole in the original.
https://static.nhtsa.gov/odi/tsbs/2014/MC-10114272-9999.pdf