serious misfire cylinder 7 , medium/mild misfires other cylinders

[Ludlow]

Hello forum! I am seeking help with my Truck, my theory is I have a problem with idle AFR, but i am no where near sure.
I will try to give as much information as possible to be of the most help. please for give me ahead of time, i am not a pro mechanic.

i am trying to solve a idle/cruising misfire problem ( misfire clears up at higher rpms) on my:

2009 gmc sierra sle 1500, 5.3 (vin M) 4x4 (299k KM)

before work was done on truck had Engine light (not sure of code) but warnings were: service trailer brake, service air bag. Lifters and cam died, decided to go with a full AFM delete kit.

the following work was done to the truck:

Truck Norris NSR cam install. including ls7 lifters, lifter trays, spark plugs,oil AFM delete oil plugs, heads re finished, valves cleaned. ect. (package purchased from Michigan motor sports.
Bench tuned PCM.

after receiving truck back from shop. there was lots of vibration. (assumed was cam chop). there was a loss of vacuum to the brakes. stalling when stopping to change gear(making 3 point turn) and was even sent into limp mode a few times. sent it back to the shop, And sent pcm back to bench tuner and traded in for a new pcm.

replaced brake booster, and installed vac can, new pcm installed. braking improved slightly. (not satisfied)

used cheap ODB reader to scan codes, got a code for oil pressure sending switch, i replaced it with a new one (and filter)

after about 500-700 kms driven, Engine light started flashing rapidly, acceleration decreased, sounded like a popping noise, like a detonation, that you can feel in the pedal. also a sluggish grinding feeling when accelerating from a stop, or low speeds.

took truck to transmission shop ( i feared for the worst) they told me trans(6l80e) is working perfect, but engine has a bad misfire.

so i replaced my spark wires with NGK wires. and coil packs with an oem option from local parts store. (still misfire)
my Hp tuners Finally arrived across the boarder and i did a dtc read.

pulled codes :
0x541: U0137 (pending, current, history)
0x543: C0299 (history)
0x543: C0561 (history)
0x7E8: P0102 (pending , old)
0x 7E8: P0113 (pending, old)

I purchased a new MAF sensor and replaced that, also cleaned air intake, throttle body with throttle body cleaner spray
cleared codes. and still none have come back. but Engine code remains.

i tested my 3 catalytic converters with a laser temp gun, and a 3-4 minute cold start test showed they were staying much cooler than the rest of the exhaust pipes/ manifold.

my misfire still is there in cylinder 7 and also some misfires in all the other cylinders. I have swapped coil and wire with cylinders 5-7 and the misfire is consistent with cylinder 7. I will replace the fuel injector in cyl 7 and see if that works.

i will attach my log and config, hopefully something sticks out of place for a trained eye? thanks in advance for any guidance!

newtuneupdatelogmms.hpl2009 Sierra 5.3 MM Mail Order Tune Anthony Agostino email tune update (2).hpt

[TragicMike]

Not a pro.. but I just compared your tune file to mine (07 non vvt).

All of the Knock Sensor Multipliers have small differences.. but cyl7 has a pretty big difference right in your idle range.
Might be worth a shot to change them by the amount shown on the pic.

KSdiff.JPG

Stock for Reference

StockKnock.JPG

[edcmat-l1]

You have a bad miss on bank 1. Can't tell the exact cylinder but it is definitely that bank. Need to check plug wires and plugs. Most common cause is cracked plug or plug wire not snapped tightly on the plug or coil or both.

Miss on bank 1.jpg

You shouldn't need a brake vacuum booster. Should work perfectly fine without one.

[Ludlow]

okay thank you for pointing that out!

[Ludlow]

the plugs and wires are brand new. i had them all pop when full plugged in. could it be a problem with the driver side(bank1) part of my fuel rail?

[GHuggins]

It's possible to have something in the top of the injector but unlikely as that will usually move around or rather come and go. You can swap injectors around and see if that makes any difference then I would recommend compression check or even pulling the valve cover since they are easy to do then inspecting valve train since you had so much mechanical work done.

[Ludlow]

if there would be anything wrong with the valve train, or compresion, would that only cause problems at idle/cruising? the misfires go away and engine light goes away as well when giving throttle. actually it runs smooth from 2000 rpm and up. throttle. im no pro but if something mechanical is of/broken, wouldnt it cause a problem the whole time? do you think what tragic mike said about knock multipliers being off being the problem?

is it possible my o2 sensors are failing, causing the miss in bank 1?

[edcmat-l1]

No. Everything points to it being a secondary ignition misfire. Cracked plug, plug wire not snapped on, etc.

[GHuggins]

if there would be anything wrong with the valve train, or compresion, would that only cause problems at idle/cruising? the misfires go away and engine light goes away as well when giving throttle. actually it runs smooth from 2000 rpm and up. throttle. im no pro but if something mechanical is of/broken, wouldnt it cause a problem the whole time? do you think what tragic mike said about knock multipliers being off being the problem?

is it possible my o2 sensors are failing, causing the miss in bank 1?

Valve seats, too long of pushrods holding a valve slightly off seat will cause the same problem for the one cylinder. Are the misfires only on the one bank? I honestly haven't looked at the log - just going by what you're saying... O2's or cats will cause whole bank issues, but you'll see that in trims.

I think everyone should remember the 5 cylinder colorado's and their valve seat problems where the seats were too soft causing built up carbon to dimple the seats. Depending on how bad the condition was it could misfire all the way to 1500 or 1800 rpms then clear right up

[Ludlow]

oh okay that makes sense. I will do a compression test to find out whats going on .

and for the cracked plug, i bought a new plug and installed it(12-13 lbs torqued), same misfires. (in cylinder 7)
the wires are definitely plugged in properly, they all made a snapping noise when doing on the plug, and the coil packs(also brand new)-connectors are pushed in as far as they can go.

for the o2 sensor, i feel like it could be a possibility. on my log, it shows both banks get voltage. between 0.04 - 0.8 . im not sure how quickly/regularly the voltage should bounce between 0 and 1 but they seem to "stick" sometimes around 0.04 and 0.600-0.700 v and never seems to max out at 0.99 ( could that be indication of a dying sensor?)

[Ludlow]

update: did compression test on bank 1, and half of bank 2 ( battery died) cylinders 1,2,3,4,5 all have 175 psi, cylinder 7 had only 12 psi. cylinders 6 and 8 are unkown for now, but either way, i have no compression in cylinder 7. https://youtube.com/shorts/lJXR0n6CM-o?feature=share i have attatched a couple videos on cylinder 7, does anything look out of place?

[Ludlow]

IMG_3964.jpgIMG_3971.jpg

got the cover off and found the intake rocker for cylinder 7 had been pushed off the pushrod. is there a way to know if the lifter is the problem without removing the head/valley cover?

[edcmat-l1]

It was either left loose or loosened up enough for it to turn.

Take the pushrod out and roll it, make sure it's not bent. Make sure the rocker bolt thread in the head are OK. Put it back together and crank it over a few times with the starter. Make sure it moves like it should.

BTW those blue FelPro gaskets only go back in once or twice before they're so out of shape you can't use them again.

[Ludlow]

update: rocker tightened up, pushrod was nice and straight as well. engine light is gone, idle is much smoother. i did another log and i notice now i have misfires in all cylinders up to 20 or so at a time. is that normal? what could cause that? also i noticed my o2 sensors behind the catalytic converters fluctuate, ( to my knowledge they should want to stay around .500, maybe im wrong! i did a dtc code read and some strange codes came up that i never had before i will post attach those aswell. once again thank you guys for your guidance! misfire7fixedrockerpushrod.hplIMG_3997.jpg