2006 GMC Envoy Denali, 5.3 LH6 Truck Norris cam Misfires are Idle

Hi Everyone,
I bought the Envoy with a spun rod bearing. I rebuilt the motor and did the DOD delete and added the Truck Norris cam. The Envoy doesn't have VVT. I have sprayed carb cleaner everywhere and do not believe I have a vacuum leak. I did a compression check on the 2 worst cylinders and they were both 120 lbs. I also added 2 grounds from the block to frame and firewall to cylinder head. It runs good above 1500 RPMs. I just added a wideband but it is only showing a voltage currently...I still have to sort that out. I am hoping this is a tune issue but I am not sure.

I have searched for P0300 but didn't find anything relavant. I am sorry if I missed the solution. I will attach the tune file and a scan file while idling.

Thank you in advance for the help!Attachment 129825Attachment 129826

You need to set the cylinder deactivation codes to no error and then raise the misfire counters by (x1.5) for starters then go with smaller amounts until the misfires aren't showing anymore. Usually a truck norris won't show that many misfires but your cal does have very low settings for misfires. I also assume you've done a crank variation relearn for the rebuilt motor and all bearing clearances were checked? Loose bearings will show misses, but shouldn't be for all cylinders unless multiple are loose.

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Originally Posted by GHuggins

You need to set the cylinder deactivation codes to no error and then raise the misfire counters by (x1.5) for starters then go with smaller amounts until the misfires aren't showing anymore. Usually a truck norris won't show that many misfires but your cal does have very low settings for misfires. I also assume you've done a crank variation relearn for the rebuilt motor and all bearing clearances were checked? Loose bearings will show misses, but shouldn't be for all cylinders unless multiple are loose.

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Thank you Ghuggins! I was able to set the cylinder deactivation codes to no error but I couldn't find where to raise the misfire counters. Under Engine Diagnostics, I went to the misfire tab, but they are all read only tables. (I just realized I need to take a training and test...which I just did) I have the tables adjusted and will try it tomorrow.

The other issue I have is the Crank Relearn, I originally did it wrong. I redid it correctly this time...I believe. But the scanner didn't confirm it was completed successfully. It is a T40 which of course if not a full Gen4. The process is to slowly press the gas until the gas cut off happens...then cycle the key after the engine comes back down to idle. I waited 15 seconds to turn it back on. The scanner didn't do anything....not sure if that is normal.

Thank you again for your help!

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Originally Posted by HPTuner newbie

Thank you Ghuggins! I was able to set the cylinder deactivation codes to no error but I couldn't find where to raise the misfire counters. Under Engine Diagnostics, I went to the misfire tab, but they are all read only tables. (I just realized I need to take a training and test...which I just did) I have the tables adjusted and will try it tomorrow.

The other issue I have is the Crank Relearn, I originally did it wrong. I redid it correctly this time...I believe. But the scanner didn't confirm it was completed successfully. It is a T40 which of course if not a full Gen4. The process is to slowly press the gas until the gas cut off happens...then cycle the key after the engine comes back down to idle. I waited 15 seconds to turn it back on. The scanner didn't do anything....not sure if that is normal.

Thank you again for your help!

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I think it's normal to not get any feedback on a lot of HPT's special functions.

Thank you!

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Originally Posted by gtstorey

I think it's normal to not get any feedback on a lot of HPT's special functions.

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That also means you need to know all the conditions that have to be met - above a certain ECT, apply brake BEFORE turning IGN to RUN, etc. It is described in your service manual. Doing it on a Tech2 you will get prompts and feedback about each step, HPT does not hold your hand and assume you don't know what you're doing.

Sorry for the delay in responding life keeps getting in the way of my project. I appreciate the confirmation gtstorey. Thank you Blindsquirrel, I did look up what was required after I did it incorrectly. GHuggins, that did it. I have a little fine adjusting to go, but it is 95% there. I appreciate everyone's help.