2009 Tahoe 5.3 135k - Cold Start Misfire. Misfires at Idle. Drives almost perfectly otherwise DOD Software Delete

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

kilgore1313

TYF Newbie
Joined
Aug 5, 2021
Posts
2
Reaction score
6
This all started a few months ago with the #4 DOD/AFM lifter failing. I didn't have time to do the work myself, so I found a mechanic that was willing to do a DOD delete. We talked and he convinced me that he could unstick the lifter and then turned off the DOD in the software. He also replaced the VLOM with an aftermarket smooth valley plate, did some exhaust work and turned off the E85 tune.

He finished the work and I drove it home. Ran perfectly until I got off the freeway. Then #7 started misfiring badly. I took it back and he said he found #7 had a cracked plug. I paid for plugs and wires and then drove it home.

Ever since then, when the truck is cold and everything is at outside temperature, it will start and drive smoothly for about 1/2 mile. At that point, it warms up enough to start misfiring. It will misfire badly until the engine gets to 210 or so and then it smooths out again. CEL and Traction control lights are flashing. After this I can drive the truck for a whole day with no issues except some minor misfiring at idle. You can feel a little shake at stop lights.

CEL codes are P0300 and P0301

My ODB tool is a little wonky, in that I see current misfire counts on 2 and history on 1, that coupled with the P0301 code makes me think something is going on with 1

I have done the following.

1. Swapped the plug in 1
2. Swapped the wire in 1
3. Swapped the coil for 1
4. Replaced the MAF (Delco)
5. Cleaned the Throttle Body
6. Replaced the MAP (Delphi)
7. Replaced all 4 o2 Sensors (Delco)
8. Replaced fuel injector 1 and all o-rings for the rest (also, 5 and 6. The plastic ring at the top had disintegrated) (Delco)
9. Ran one tank of Lucas Fuel System Cleaner
10. 1/4 of a tank with a bottle of Techron
11. New air filter.

I have tested the compression on cylinder 1 and it comes back at 120, cylinder 3 has 140.

Am I missing anything obvious? I think the next step is for me to start looking for vacuum leaks.
 
OP
OP
K

kilgore1313

TYF Newbie
Joined
Aug 5, 2021
Posts
2
Reaction score
6
Update: 2 days ago I started hearing the lifter tick at startup. It would smooth out pretty quickly. Today it's ticking at all times. Looks like time for a full delete. I will update here with those results, just in case anyone can learn from my experience.

I saw a couple of mentions that the unstick trick is just a temporary fix and that once the DOD/AFM goes bad it must be hardware deleted. This has been my experience 100%. If your lifters are sticking, do the hardware delete ASAP.
 

Dustin Jackson

Full Access Member
Joined
Aug 9, 2018
Posts
1,376
Reaction score
1,529
I hope the AFM delete can resolve your original problems, thanks for the update we are watching
 

Forum statistics

Threads
128,783
Posts
1,805,340
Members
91,761
Latest member
AlbertoTahoe2011
Top