Help with cylinder 5 misfire P0305 (sorry, long post... but stumped)

[Rocket Man]

There is a TSB that might relate to this which concerns the valvetrain:

#PIP4138Q: SES Light, Misfire, DTC P0300, And/or A




Chirp, Squeak, Squeal, Or Tick Noise - Potential Valvetrain

Concern - (Jan 24, 2018)

Subject: SES Light, Misfire, DTC P0300, And/or A Chirp, Squeak, Squeal, Or

Tick Noise - Potential Valvetrain Concern

Brand: Model:

Model Year: VIN:

Engine: Transmission:

from to from to

Buick

Allure

(Canada

Only)

2008-2009 All All V8 ALL

Buick LaCrosse 2008-2009 All All V8 ALL

Buick Rainier 2004-2007 All All V8 ALL

Cadillac CTS-V 2006-2018 All All V8 ALL

Cadillac Escalade 2002-2018 All All V8 ALL

Chevrolet Avalanche 2002-2013 All All V8 ALL

Chevrolet

Caprice

PPV

2011-2018 All All V8 ALL

Chevrolet Colorado 2009-2012 All All V8 ALL

Chevrolet Camaro 2010-2018 All All V8 ALL

Chevrolet Corvette 2005-2018 All All V8 ALL

Chevrolet Express 2002-2018 All All V8 ALL

Chevrolet Impala SS 2006-2009 All All V8 ALL

Chevrolet

LCF

Models

2016–2018 All All V8 ALL

Chevrolet

Monte

Carlo SS

2006-2007 All All V8 ALL

Chevrolet SSR 2003-200©6 2018 GeneralA Mllotors. All riAglhlts reservedV. 8 ALL

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Brand: Model:

Model Year: VIN:

Engine: Transmission:

from to from to

Chevrolet Silverado 2002-2018 All All V8 ALL

Chevrolet

Silverado

HD

2002-2018 All All V8 ALL

Chevrolet Suburban 2002-2018 All All V8 ALL

Chevrolet Tahoe 2002-2018 All All V8 ALL

Chevrolet TrailBlazer 2003-2009 All All V8 ALL

GMC Canyon 2003-2009 All All V8 ALL

GMC Envoy 2003-2009 All All V8 ALL

GMC Savana 2002-2018 All All V8 ALL

GMC Sierra 2002-2018 All All V8 ALL

GMC Sierra HD 2002-2018 All All V8 ALL

GMC

Yukon

Models

2002-2018 All All V8 ALL

Hummer H Models 2003-2010 All All V8 ALL

Pontiac G8 2008–2010 All All V8 ALL

Pontiac GTO 2005–2006 All All V8 ALL

Pontiac

Grand

Prix GXP

2005–2008 All All V8 ALL

Saab 9-7X 2005-2009 All All V8 ALL

Supersession Statement

This PI was superseded to update Model Years. Please discard PIP4138P.

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern

Some customers may complain of a SES light, engine misfire, and/or engine noise.

If the SES light is on, the technician will find a P0300-P0308 DTC with misfires counting on a

single cylinder that may or may not be felt.

This may occur consistently, or it may occur intermittently.

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If a noise is verified, it will not be eliminated by canceling fuel injectors and the noise will occur at

camshaft speed (half of crankshaft speed).

The noise may be described as a chirp, squeak, squeal, or tick noise and may increase off of idle.

In either case, the cause of this concern may not be isolated after following SI diagnosis. This PI

is written for technicians who experience this concern and follow SI diagnosis without isolating the

cause of this concern.

Recommendation/Instructions

If SI diagnosis does not isolate the cause of this concern, it may be the result of any of the

following:

1. Worn camshaft lobe and/or lifter roller

2. A sticking valve

3. Valve leakage

4. A broken valve spring

5. A collapsed AFM (Active Fuel Management) lifter.

If SI diagnosis does not isolate the cause of this concern, review the information below, determine

which description best matches the vehicle you are working on, and perform the suggestions as

necessary, starting with the easiest ones first:

1. Worn Cam Lobe and/or Lifter Roller:

Generally, a worn cam lobe on this engine family will create a consistent chirp, squeak, squeal, or

tick noise at camshaft speed and/or a misfire with a P0300-P0308 DTC. The misfire may or may

not be felt and the misfire could occur at all RPM or just a specific RPM, such as idle only or only

at high RPM. If a noise is present, it will not be eliminated by cancelling fuel injectors and

generally, the static compression and cylinder leakage will be similar on all cylinders.

The following suggestions may help determine if a worn cam lobe and/or lifter is causing this

concern:

• Use a wooden hammer handle to apply pressure to the following locations of the rocker

arms during the noise to determine which one is making noise: valve side, push rod side,

and side of the rocker. If the noise is changed by applying pressure to the valve side of the

rocker, this is most likely the result of a lifter and/or cam lobe concern on that cylinder.

Sometimes this works, sometimes it does not - it seems to depend on the amount of cam

lobe wear.

• Disconnect the coils and injectors on one bank of the engine, run the engine with the

related valve cover removed, and back off the related rocker arm a couple of turns and

listen for a change in the noise. If necessary, both rockers and push rods can also be

removed one cylinder at a time with the related coil and injectors disconnected. If the noise

is eliminated and there is no problem found with the valve spring, push rod, or rocker arm,

this is most likely the result of a worn lifter roller and/or cam lobe.

• Measure the cam lobe lift at the push rod side of the rocker arm. The lift in this location will

differ from the SI specification but it should be similar as compared with other rockers on

the same bank. The misfiring/ticking cylinder should obviously have less lift than the

comparison cylinders if this is the result of a worn lifter roller and/or cam lobe. Another

possibility of no/low lift on cylinders 1, 4, 6, or 7 on an AFM engine would be a collapsed

AFM lifter. If a collapsed AFM lifter is found, refer to the latest version of PIP4568 for

additional information.

• On engines with AFM (active fuel management), you can command AFM on with the scan

tool, which will unlatch the lifters on cylinders 1, 4, 6, and 7 and stop opening the related

valves. If the noise is eliminated, there is a good chance that the noise is coming from the

valvetrain of cylinders 1, 4, 6, or 7. If there is no problem found with the push rods,

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rockers, or valve springs, the noise is most likely coming from a worn lifter roller and/or

cam lobe on cylinders 1, 4, 6, or 7.

Note: The above step will not work on 2017 and 2018 models.

• If the tests above do not isolate the cause of this concern, it may be necessary to visually

inspect the lifter rollers and cam lobes for obvious damage, such as flat spots, pits, grooves,

scoring, gouging, flaking, rusting, etc...It is very easy to overlook a damaged cam lobe

when inspecting them through the lifter bores and just because the lifter rollers are not

worn, does not mean that the related cam lobes are okay. Both pieces need to be carefully

inspected. It may help to use a bore scope or pen light when inspecting the cam lobes

through the lifter bores. In some cases, the worn cam lobe may not be discovered until the

camshaft is physically removed from the engine and inspected for the issues mentioned

above.

Notice: Follow SI procedures to replace the camshaft and all lifters if a worn camshaft lobe

or lifter roller is found. Also replace the plastic lifter guide for the lifter that had the

damaged cam lobe and/or lifter roller (For 2010 Model Year, replace all of the

plastic lifter guides). On AFM engines, also replace the VLOM (Valve Lifter Oil

Manifold) filter screen that is under the oil pressure sensor.

2. Sticking Valve:

Generally, a sticking valve on this engine family will cause an engine misfire that may or may not

be felt and it may occur consistently or intermittently. It is unlikely that any engine noise will be

present. It may be temperature sensitive and it may be more apparent during certain operating

conditions, such as driving up a grade, cresting a hill, or during hard acceleration. A good

indicator of a sticking valve is if engine misfires continue to count on an aggressive deceleration

with engine braking. If the misfire occurs consistently, a static compression test, running

compression test or cylinder leakage test may isolate the sticking valve. However, it is unlikely

that any of these tests will isolate the sticking valve if the misfire only occurs while driving at

specific conditions.

The following suggestions may help determine if a sticking valve is causing this concern:

Follow SI procedures to remove the valve springs and seals from the valves of the misfiring

cylinder. Before removing the air pressure from the cylinder, tightly wrap a rubber band or tie

strap around the tip of each valve stem to prevent the valves from dropping into the cylinder.

Release the air pressure from the cylinder and work the valve up and down in the guide while

turning the valve 360 degrees.

If any binding is felt, a stem to guide clearance concern exists and should be repaired by following

SI procedures.

If okay, rotate and snap the valve onto the valve seat to make sure that it easily comes off of the

seat again. If you have to use force to tap the valve off of the seat, excessive carbon build up

exists, which may be repaired by decarboning the engine.

Notice: Refer to the latest version of PIP4753 for decarboning instructions.

3. Valve Leakage:

Generally, valve leakage on this engine family will cause a consistent engine misfire that may or

may not be felt and is more apparent at idle or low RPM. Normally, no engine noise will be present

and in most cases, a static compression test or running compression test will not reveal anything

abnormal unless the leakage is very high.

Typically, the Cylinder Leakage Test outlined in SI should isolate valve leakage by finding

excessive leakage past an intake or exhaust valve, as compared with others.

Notice: If a valve sealing concern is found, it should be repaired by following SI repair

procedures.

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4. Broken Valve Spring:

Generally, a broken valve spring on this engine family will cause a tick noise and/or an engine

misfire. In either case, the concern may occur consistently or intermittently. If it is causing an

engine misfire, it may or may not be felt and it may only occur at specific operating conditions,

such as high RPM driving, etc...

In some instances, a static compression test, running compression test, and/or cylinder leakage

test may isolate the broken valve spring, while in other instances; it may not if the spring remains

stacked together during the tests. As a result, it may be necessary to visually inspect the valve

springs by closely examining them. Sometimes, the two broken pieces of the spring will remain

stacked together so it may be hard to detect when visually inspecting them. As a result, it may

help to lightly push on different places on the springs with a small hammer handle.

Notice: If a broken valve spring is found, replace the broken valve spring as necessary.

5. Collapsed AFM Lifter (Engines with AFM Only):

Some customers may comment on an SES light, engine misfire, and/or tick noise. This may be

the result of an AFM lifter that unlocks as soon as the engine is started or one that is mechanically

collapsed/stuck.

If an AFM lifter unlocks as soon as the engine is started, a SES light and DTC P0300 will be

experienced with engine misfires on cylinder 1, 4, 6, or 7 but it is unlikely that any noise will be

experienced. If an AFM lifter is mechanically collapsed/stuck, a consistent valve train tick noise,

SES light, and DTC P0300 will be experienced with engine misfires on cylinder 1, 4, 6, or 7.

Notice: If either of these AFM lifter concerns is suspected, please refer to the latest version of

PIP4568 for additional information.

Notice: If there is an AFM lifter concern on RPO's L83, L86, LT1 and LT4 follow 15-06-01-002E.

Warranty Information

For vehicles repaired under warranty, please use the appropriate warranty labor operation based

on the actual cause and repair.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition

exhibited is resolved without completing every step, the remaining steps do not need to be

performed.

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these

technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a

vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and

safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that

condition. See your GM dealer for information on whether your vehicle may benefit from the information.

WE SUPPORT

VOLUNTARY

TECHNICIAN

CERTIFICATION

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[mckpaul]

James - Yeah that's kind of what I was thinking. I didn't notice any metal shavings in my last oil change. Now I'm wishing the when I did the intake manifold gaskets that I would have pulled the VLOM manifold to take a peek under it. From what I've seen in pictures you can see the bottom of the lifters where they ride on the cam. Not sure if you can see both intake and exhaust, but looked like there were small openings just big enough to see a little bit of the cam and lifter. But I agree, I don't think there's a rotated lifter. I think that would make enough noise to be heard without the stethoscope , and I also think it would have been REALLY loud through the stethoscope.

Mark - That TSB had a lot of info in it. I'm going to see if I can find a pdf of it online and save it, or copy and paste to WORD. Of course the links to side procedures said I didn't have authority to open them, but that gave me some things to check on that exhaust rocker. I looked at the valve springs on the sides I could see and felt around the back sides, nothing looked or felt unusual, but if...(or more likely,when).. I get back into the valve cover I'll get a close look all the way around. I have one of those flexible gooseneck USB inspection cameras that will give me a view of the back sides up close. Looks like that TSB just came out in January. Obviously some of it is about the AFM system and luckily at the moment my issue doesn't involve any of those cylinders. I have to wonder if all that is just a problem waiting to happen, but then again as I researched the AFM stuff it kind of looked like most of the vehicles with issues were from the earlier years of the AFM technology, didn't see as many newer year vehicles with problems. But...that could be because they haven't been on the road as long.

If it comes to breaking into the engine for lifters and cam, I may do the AFM delete. I have to wonder how much mileage a fully functional AFM system really adds and if it's worth keeping, replacing the VLOM manifold and such during the repair.

There's a ton of info on the web about the 5.3 engines up to '07. There are several changes made in '07. When I was looking for intake manifold bolts I found that starting in '07 they no longer have the crush washer on the bolts. The knock sensors are no longer under the intake and now on the sides of the engine (I guess because of the VLOM being under the intake instead) The cam position sensor is moved to the timing chain cover. Just saying, when searching for youtube videos for various procedures (to learn from other peoples mistakes lol) there aren't as many out there for the '07 & up Tahoes.

I appreciate the input on all this. I don't have to get inspected until November, but right now if I had to, I couldn't. And this is my daily driver...that I'm paying a car note on...and it's driving me crazy and running me in circles. I've never had this much trouble solving a problem. On one hand it seems so minor, you really almost can't feel the miss, only at stop lights, it's not audible tapping noises, the drivabilitiy is down some, but not a major, but looking more and more like the heads need to come off and the cam pulled out. On a side note, still haven't ruled out the cats. I found some info that said a quick way to get an idea if the cats are contributing to the problem is to pull the upsteam O2 sensors (basically venting the exhaust before the cat) and see if things improve, but sounds like that would cause just as many or more issues when the ECM loses it's input. I guess if I did it on a cold start when it's running open loop and check for misfires it might do some good, but I have my doubts.

 

[mckpaul]

Well, I gave up and dropped the truck off at a GM certified shop near me. After a couple of days messing with it he called and said he was pretty sure it was a lifter so I told him to go ahead and dig in. He found the exhaust lifter on #5 to have a roller that was kind of chewed up and the cam was damaged as well. I attached a pic of the lifter, I hope it's visible. It's frustrating because No. 5 not even an AFM cylinder. He said the plastic lifter tray wasn't cracked and it didn't appear the lifter had rotated, not sure why it did what it did. However I'm not the original owner, it was a trade in vehicle at a Ford dealership when I purchased it back in November. It may have had repairs prior to me buying it that were done poorly just to make it run to trade it in.

So of course that meant new cam and all new lifters. I made sure he got the newest updated GM lifters, replace the plastic lifter trays, and had him change the VLOM to the newer updated version. Knowing he was going to have the timing chain cover off and would be looking at the oil pump, I had him replace that too.

The truck now idles quietly and smoothly, no misfires, and has the throttle response of a new truck.

On a side note, a week prior to the repair I put new y-pipe/cats on the truck, bought it online from AB Catalytic, exact bolt up replacement. Since I got the truck back it threw a P430 code, poor cat performance bank 2. The cats are literally 3 week old and only ran a limited amount on the engine with the bad lifter before the repair. I know the cats are good. I don't want to continue on that topic on this thread, I'm going to start a new one on just that subject. Just wanted to say thanks to all who shared their thoughts, and post the solution to the P0305 misfire in hopes it helps someone who finds this discussion later.

 

[mckpaul]

Sorry...this was a duplicate of the one above..computer locked up and I accidentally posted twice but couldn't find a way to delete.