2022 Tahoe random misfire

MixedQiwi · June 30

Hello everyone. Came here with 2022 tahoe GM 6.2 L87 engine problem. 4th cylinder randomly misfires without MIL. When it came to us two months ago it was randomly misfiring by all of the cyilinders, but 1,4,7 were the most. MIL was shown up. Since then we found melted catalytic converter on the left side (1,3,5,7) and changed it. Checked cylinder compression - it is approx. 220 psi (15.5 bar) in every. Changed all of the injectors. Changed all of the spark plugs, wires and coils. All of the spark plugs were completely worn. Now it has only one problem cylinder. It could work without misfire for 1-3 hours staying at idle or start to misfire when accelerator slowly and gently pushed towards to reach approx. 1.5-2k rpm doing 6-25 misfires per logging cycle. No tickling noise. Opened both rocker covers to look at the lifters. They are not stuck when engine is idling. When pushing accelerator fast and completely, or just sharply and briefly push - there are no misfires at all and it stops misfiring if there are some. Total mileage is 25000 miles. 13000 miles ago it had stuck lifter on the right head (2nd cylinder, intake valve). Since then, all of the lifters on the right head have been replaced. Oil pressure is 40 psi at cold engine and 30 psi at hot. Fuel corrections are: -0,5% long bank 1 -1% - -4% - -7% long bank 2 (high percentage when misfires obviously from enriching the mixture with unburned fuel) Short-term correction jumps from 1% in plus to 5-7% in minus, depending on misfires in right bank. Coolant level is constant i guess. Camshaft without any scratches or damages. Could new injector be broken by the chance? Will try to change 4th injector on monday and swap 4th and 3rd AFM system solenoid but it hardly would work. I'll be glad to hear your opinions.

Edited June 30 by MixedQiwi

asilverblazer · July 1

Swap injector from a good cylinder to the bad one. See if the miss fire follows.

Make sure they are legit GM injectors!

Smoked CAT probably from running with the miss too long.

theroutfield · August 13

On 6/30/2024 at 7:52 PM, MixedQiwi said:

Hello everyone. Came here with 2022 tahoe GM 6.2 L87 engine problem. 4th cylinder randomly misfires without MIL. When it came to us two months ago it was randomly misfiring by all of the cyilinders, but 1,4,7 were the most. MIL was shown up. Since then we found melted catalytic converter on the left side (1,3,5,7) and changed it. Checked cylinder compression - it is approx. 220 psi (15.5 bar) in every. Changed all of the injectors. Changed all of the spark plugs, wires and coils. All of the spark plugs were completely worn. Now it has only one problem cylinder. It could work without misfire for 1-3 hours staying at idle or start to misfire when accelerator slowly and gently pushed towards to reach approx. 1.5-2k rpm doing 6-25 misfires per logging cycle. No tickling noise. Opened both rocker covers to look at the lifters. They are not stuck when engine is idling. When pushing accelerator fast and completely, or just sharply and briefly push - there are no misfires at all and it stops misfiring if there are some. Total mileage is 25000 miles. 13000 miles ago it had stuck lifter on the right head (2nd cylinder, intake valve). Since then, all of the lifters on the right head have been replaced. Oil pressure is 40 psi at cold engine and 30 psi at hot. Fuel corrections are: -0,5% long bank 1 -1% - -4% - -7% long bank 2 (high percentage when misfires obviously from enriching the mixture with unburned fuel) Short-term correction jumps from 1% in plus to 5-7% in minus, depending on misfires in right bank. Coolant level is constant i guess. Camshaft without any scratches or damages. Could new injector be broken by the chance? Will try to change 4th injector on monday and swap 4th and 3rd AFM system solenoid but it hardly would work. I'll be glad to hear your opinions.

geometry dash wave

Sounds like your problem is due to the quality of the injectors and cylinders in the last replacement as I don't think using genuine parts would damage it so quickly. Check again and find a reputable place to replace it.

Edited August 13 by theroutfield