Engine Pinging

[coz3z3]

Hello again!

13 Yukon Denali L94, around 195k on replacement motor.
Many of you helped with my recent engine replacement, well the next one is in and I can't figure out what the issue may be. The engine is pinging. Not knocking, not ticking. At first, I thought it was bad gas, and I still haven't completely ruled that out. The gas was well over 1.5 years old. When I got this yukon, the tank was full. I tried to a ton of stabil and cleaners to help at first. It pinged for about 10 minutes before it went away. I was able to drive it for 3 days, about 50 miles, and got the tank to just about the 3/4 mark. Ran like a champ. Then it started pinging again. This time worse. I dropped the tank, siphoned it all out except maybe .5 a gallon. Put me 91 in there with some more cleaner. Now I'm getting a misfire on cylinder 5. I've changed coil, fuel injector, spark plug wire with no avail. The plugs are brand new, my next step is to swap with another cylinder and see if it follows. I did swap with one of the older plugs from the old block and that didn't help. I'm at a loss. I thought it could be the AFM but read that isn't a cylinder that shuts down. But it doesn't sound like a lifter tick. It sounds like predetonation from bad gas. A ping. And I've tried disconnecting the battery to reset the fuel trims as well. Multiple times.

Thank you again!

 

[Trey Hardy]

Hello again!

13 Yukon Denali L94, around 195k on replacement motor.
Many of you helped with my recent engine replacement, well the next one is in and I can't figure out what the issue may be. The engine is pinging. Not knocking, not ticking. At first, I thought it was bad gas, and I still haven't completely ruled that out. The gas was well over 1.5 years old. When I got this yukon, the tank was full. I tried to a ton of stabil and cleaners to help at first. It pinged for about 10 minutes before it went away. I was able to drive it for 3 days, about 50 miles, and got the tank to just about the 3/4 mark. Ran like a champ. Then it started pinging again. This time worse. I dropped the tank, siphoned it all out except maybe .5 a gallon. Put me 91 in there with some more cleaner. Now I'm getting a misfire on cylinder 5. I've changed coil, fuel injector, spark plug wire with no avail. The plugs are brand new, my next step is to swap with another cylinder and see if it follows. I did swap with one of the older plugs from the old block and that didn't help. I'm at a loss. I thought it could be the AFM but read that isn't a cylinder that shuts down. But it doesn't sound like a lifter tick. It sounds like predetonation from bad gas. A ping. And I've tried disconnecting the battery to reset the fuel trims as well. Multiple times.

Thank you again!

On my higher mileage Tahoe 87 would cause it to spark knock it almost sounded like a rod bearing was going bad I put some B12 in the tank and never had the issue again so whenever I run cheap gas I always throw some B12 or a lil marvel mystery oil in with it and it helped eliminate the spark knock

 

[Marky Dissod]

 

[OR VietVet]

Are you seeing a CEL? If so, what was the code(s)?

 

[Foggy]

Add in some "good" octane booster. Lucas, Purple stuff, etc
That would rule out a true predetonation with your 91 fuel.
Also see if you can get 100% gasoline with zero ethanol
The cleaners are full of alcohol type chemicals and could be
adding to the issue

 

[j91z28d1]

when you say plugs were replaced, what kind and where did you get them?

so many bad parts going around

 

[Foggy]

Great point on the spark plugs !!!! Use the ACDelco irridium from a known
source: local parts store, rockauto, summit racing.... NOT: amazon or ebay

 

[coz3z3]

Hello!
Sorry for the late reply, I wasn't getting notifications and decided to check the forum this morning.
I will look at that B12 some more. I have added cleaners, not necessarily octane booster. The cleaners were Lucas, and Amsoil. They both said it should eliminate the predetonation.
Spark Plugs are Delco from O'Reilly. Can't remember the part number off the top of my head, bit they should be what came in it.

CEL has come on. My reader says P0300 is permanent for multiple misfires. Then the only cylinder to post is cylinder 5. P0305. I did get one code for Bank 2 being lean. I thought was weird since that is opposite of cylinder 5. But it only happened once and I cleared it and hasn't come back.

The CEL will come on along with service stabilitrak and all that, then after a couple minutes, they all disappear. Codes stay in computer of course.

Also, the pinging is irratic. Sometimes it is super loud, sometimes it disappears completely for about 2 minutes and then comes back. No matter if it's cold, warm, rpms up, at idle.

Thanks again everyone

 

[coz3z3]

Also, I did swap spark plugs with cylinder 1. No change. I then swapped coil and wire with cylinder 1, no change. I removed the valve cover and all the rockers moved in what seemed like normal fashion. My next step is to get one of those camera scopes and check inside cylinder 5. I'm pretty dumbfounded by this. After that, I'll trace some wires. I've tried unplugging the fuel injector, and coil from cylinder 5 and there has been no change. I'm almost leaning towards a lifter now. But I'm just confused why it goes away sometimes, and it doesn't follow the rpms all the time. It gets faster when the rpms do, but sometimes will slow or go away completely and then not return for 5-10 minutes. Then it comes back slow and not loud.

 

[Trey Hardy]

Hello!
Sorry for the late reply, I wasn't getting notifications and decided to check the forum this morning.
I will look at that B12 some more. I have added cleaners, not necessarily octane booster. The cleaners were Lucas, and Amsoil. They both said it should eliminate the predetonation.
Spark Plugs are Delco from O'Reilly. Can't remember the part number off the top of my head, bit they should be what came in it.

CEL has come on. My reader says P0300 is permanent for multiple misfires. Then the only cylinder to post is cylinder 5. P0305. I did get one code for Bank 2 being lean. I thought was weird since that is opposite of cylinder 5. But it only happened once and I cleared it and hasn't come back.

The CEL will come on along with service stabilitrak and all that, then after a couple minutes, they all disappear. Codes stay in computer of course.

Also, the pinging is irratic. Sometimes it is super loud, sometimes it disappears completely for about 2 minutes and then comes back. No matter if it's cold, warm, rpms up, at idle.

Thanks again everyone