Converter Not Locking up

I have a 2006 LQ4 (P59 PCM) with a 4L80E swapped in to a 62 C20 pickup. I used the factory harness and drive by wire throttle pedal. All of the unnecessary wiring was removed from the harness and an aftermarket fuse panel was used to power everything. The engine is completely stock other than a set of flex fuel injectors from a newer truck. The injector information was updated in the tune and it seems to run just fine with no misfires.

I did use the stock MAF sensor in the setup. I'm a little confused that it keeps commanding a 16 to 1 AFR also, not sure why it's doing that.

The problem I am having is that the converter will not consistently lock up. If I have the scanner hooked up and look at the current codes I don't have anything showing. If I hit the Clear Codes button while driving the converter locks up right away and stays locked until I come to a stop again and then it won't work.

This is my first experience with an LS motor and tuning anything with fuel injection. The tune is attached below if anyone can take a look at it and see if there is something incorrect it would be much appreciated.

The reason for the 16 commanded AFR is because of a cat test. If you install the rear o2 sensors back in, the test should stop. They don't have to be in the exhaust, the circuits just need to be completed.

Many codes you set to "No MIL Light" instead of "No error reported". Go back and check/change all the codes to no error reported for rear o2 sensors, cat codes, evap codes and so on.

I did have the O2 sensor codes all set to No Error Reported and it acted the same way, converter won't lock all the time. I read in another thread that setting them to No MIL Light would keep it from commanding the lean AFR reading, obviously that does not work, lol.

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Originally Posted by bubba2400

I did have the O2 sensor codes all set to No Error Reported and it acted the same way, converter won't lock all the time. I read in another thread that setting them to No MIL Light would keep it from commanding the lean AFR reading, obviously that does not work, lol.

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P59s have this issue whether O2 codes are set to "no error report" or not.

Plug in your rear O2s and just hang them somewhere. Dont even gotta be in the exhaust.
P59s do this for some reason.

Would this keep the converter from locking up? That is my main concern at this point.

I can put the O2's back in under the hood to alleviate the lean commanded AFR without a problem.

Does scanner TCC Status show locked but the converter doesn't lock? Or does TCC Status never show locked? Any chance your cobbled harness is giving a brakes applied signal to the PCM?

It locks the first time when starting the truck and driving, I wasn't real clear on that one. But then while driving it unlocks (can hear it since it has a stall converter) and never locks again until after a key cycle.

I actually unhooked the brake switch to make sure it wasn't getting a signal and chased the harness to check for a short to ground or power.

If I have the scanner running and I clear the codes, even with nothing showing up for codes, it locks the converter immediately. Of course it doesn't stay locked for long.

So it almost seems as though the PCM is throwing a code but because I have a bunch of them set as No Error Reported it doesn't show it as having any. I'm kind of at a loss and frustrated at this point. I just want to drive the stupid thing and not work on it anymore, lol.

Log current misfires and misfire history for each cylinder.

#3 misfires when I get above 50% throttle or so. I will take a look at why it's doing that and hopefully that fixes it!! I will report back what I find. Thanks

My 05 2500hd did this exact same thing when it was stock. No codes never could figure it out. I have since ditched the maf and run it speed density. The converter locks as it should. Unplug your maf and write a maf fail tune and try it

Finally getting back to this. Had misfire on #3 pretty bad, swapped a bunch of ignition components around to different cylinders to see if the problem followed and it never did. Just swapped injectors from side to side and looks like two injectors are the problem. Going to toss the stock injectors back in and see if it clears up.

Davem3261, interesting you say that you run your's off on speed density only, when I was tuning the VE table I felt like it ran way better. I may just go back to that and leave it alone depending how it acts with the stock injectors in it.

Misfire detection can be disabled when in SD on some OSs. With no misfires detected, even though the engine is experiencing real misfires the converter will lock.

Just a quick follow up on this: Found the fuel cap was letting water in to the tank :(. Fixed that, drained the entire fuel system, changed the cross over tube on the rails which seemed like it had rusted inside, swapped back to the stock injectors, cleaned the rails really well and now it runs like a top. When I find a PCM that is flex fuel enabled I will put another set of bigger injectors back in it so I can run e85. Right now I'm just happy it runs smooth again!! Thanks to anyone who gave advice on the issue, much appreciated.