2015 silverado 1500 lt 5.3L E92 6L80E help

[doobiebanditt]

You need to figure out what's causing the miss. It's not the MAF unless fueling is WAY out. Only reason you're not seeing a miss with it not there is because of dtc and logic operations within the ecm.

Could be something real simple and cheap like a bent pushrod. Verify valve train first. If it's good and good compression then it's the injector.

Ok I checked lifters today no play on any on driver side so that rules out bent rod / collapse lifter tommarow I'm gonna get my dad's compression test and check the heads

[GHuggins]

As long as you checked for play at 0 lash. Rockers are easy enough to take loose if you want to remove the ones for that cylinder and just make sure you can roll them on a flat table without them wobbling. You can even spin the engine over with them in place and make sure the valves are functioning correctly. You could even do that tomorrow while checking the compression. Make sure to compare it to a neighboring cylinder. If all this checks out then do a set of injectors. Do all 8 and not just one too.

[doobiebanditt]

As long as you checked for play at 0 lash. Rockers are easy enough to take loose if you want to remove the ones for that cylinder and just make sure you can roll them on a flat table without them wobbling. You can even spin the engine over with them in place and make sure the valves are functioning correctly. You could even do that tomorrow while checking the compression. Make sure to compare it to a neighboring cylinder. If all this checks out then do a set of injectors. Do all 8 and not just one too.

Checked for play at 0 lash what do you mean. Sorry first time doing something like this and I'll recheck tommarow as well in daylight

[GHuggins]

0 lash is when there is no pressure (valve not open and on the compression stroke)

The rockers should torque to 22 lbft. You can remove them then remove the pushrods and roll them on a flat surface. If bent you'll know. OR while checking compression just watch for proper valve movement. Compression should show if further investigation is required either way if you don't want to take anything in the valve train loose.

[Alvin]

i'd put my money on a bad plug/wire.

I've gotten like 5 dead plugs straight out of the box in my lifetime. Go in... they miss. pull them out after a good bit of run time and they look absolutely brand new.


New plugs/wires would be my first step.

[doobiebanditt]

0 lash is when there is no pressure (valve not open and on the compression stroke)

The rockers should torque to 22 lbft. You can remove them then remove the pushrods and roll them on a flat surface. If bent you'll know. OR while checking compression just watch for proper valve movement. Compression should show if further investigation is required either way if you don't want to take anything in the valve train loose.

Ok so an update I took it to My dad's to have him take a look at it. He used his snap on scanner to check injectors each one were passing the pulse test and read good. It also showed a code for invalid data received from ecm and he trying to figure that issue out as he believes that is one of the issues. Have yall ever ran into this issue if so any insight on how to resolve it. Vehicle has been in a reck on driver side were the fuse box sits it moved harneses but no visual signs of damage.if you think that is one of the issues I'm looking at. Still haven't pulled the rockers and checked the rods since it been raining all day over here didn't wanna get anything all wet.

[doobiebanditt]

i'd put my money on a bad plug/wire.

I've gotten like 5 dead plugs straight out of the box in my lifetime. Go in... they miss. pull them out after a good bit of run time and they look absolutely brand new.


New plugs/wires would be my first step.

I have replaced all plugs and moved my wires around havnt bought new ones as these are still new but figured if one is damaged moving then around should of moved the misfire but misfire still stayed in same spot

[GHuggins]

Ok so an update I took it to My dad's to have him take a look at it. He used his snap on scanner to check injectors each one were passing the pulse test and read good. It also showed a code for invalid data received from ecm and he trying to figure that issue out as he believes that is one of the issues. Have yall ever ran into this issue if so any insight on how to resolve it. Vehicle has been in a reck on driver side were the fuse box sits it moved harneses but no visual signs of damage.if you think that is one of the issues I'm looking at. Still haven't pulled the rockers and checked the rods since it been raining all day over here didn't wanna get anything all wet.

Just because an injector is showing pw doesn't mean it's mechanically opening. That's the problem with these high pressure injectors. They get stuck shut or open or leak as far as that goes.

Do the compression check. Compare to another cylinder. Use a spark tester if you haven't. Make sure the plug is actually sparking. If you have sparky spark and good compression then it's the injector. Dead misses are fairly simple.

Fuse box shouldn't be a problem as long as you have sparky spark especially with one cylinder.

[doobiebanditt]

Just because an injector is showing pw doesn't mean it's mechanically opening. That's the problem with these high pressure injectors. They get stuck shut or open or leak as far as that goes.

Do the compression check. Compare to another cylinder. Use a spark tester if you haven't. Make sure the plug is actually sparking. If you have sparky spark and good compression then it's the injector. Dead misses are fairly simple.

Fuse box shouldn't be a problem as long as you have sparky spark especially with one cylinder.

Ok so far check the pressure in cylinder 5 and compared to cylinder 1 cylinder 5 hit 180 but stayed at 160 same with cylinder 1.

[GHuggins]

Valve spring and rocker look good while spinning it over? Looking more like an injector as long as you're sure you have spark on that plug.

[doobiebanditt]

Valve spring and rocker look good while spinning it over? Looking more like an injector as long as you're sure you have spark on that plug.

Ok checked compression in cylinder 7 only getting 92 did test qgain getting 122 turning over and cut off not like the other hitting 180 and dropping did it aging it hit 160 and stayed at 160 and I did the injector pressure test with the scanner again not sure how accurate it is but cylinder one reading 33.9
Cylinder 2 40.5 Cylinder 3 28.4 Cylinder 4 44.2
Cylinder 5 26.9 Cylinder 6 35.8 Cylinder 7 31.0 Cylinder 8 40.1 those were the reading forthe injector balance test per Cylinder with snap on scanner

[GHuggins]

Cyl 5 was the one with the dead miss at least in the last log you posted. Interesting. Cyl 7 is a DOD cylinder. Do the same valve train checks for it.

[doobiebanditt]

Cyl 5 was the one with the dead miss at least in the last log you posted. Interesting. Cyl 7 is a DOD cylinder. Do the same valve train checks for it.

linder 5 compression was good at crank did 180 than drop to 160 and held. I'm thinking imma try and swap all 8 injectors out. Should I upgrade to l86 injectors well it gives me more power or stay with the oem l83

[GHuggins]

You won't get more power, just more headroom and that's if you go to the higher flow ones specifically. You also might need to do some minor changes in the cal for them. That still wouldn't answer the low compression on cyl 7 question...

[doobiebanditt]

You won't get more power, just more headroom and that's if you go to the higher flow ones specifically. You also might need to do some minor changes in the cal for them. That still wouldn't answer the low compression on cyl 7 question...

i ended up re checking spark turns out cyllinder 5 was getting no spark. i got my meter checked the connector and one wire had 1 volt i compared to another connector and it had 14 volts so i ran a test jump wire and it stoped missing but then i got a miss in cylinder 6 now for some reson but 5 and 7 stoped with jumper wire do you have a wire diagram i can use to chase the wire i dont wanna just start cutting into harness lol.

[GHuggins]

i ended up re checking spark turns out cyllinder 5 was getting no spark. i got my meter checked the connector and one wire had 1 volt i compared to another connector and it had 14 volts so i ran a test jump wire and it stoped missing but then i got a miss in cylinder 6 now for some reson but 5 and 7 stoped with jumper wire do you have a wire diagram i can use to chase the wire i dont wanna just start cutting into harness lol.

I don't have access to service info at the moment, but I would say you're looking for a bad splice or corrosion at the voltage feed if that's the case.

[doobiebanditt]

I don't have access to service info at the moment, but I would say you're looking for a bad splice or corrosion at the voltage feed if that's the case.

yes im getting all data in a moment and gonna go from there