This thread could really be titled "How do I get my idle to hang" and that would probably answer my questions. Here's the details though.
I have a 2007.5 Silverado that I swapped the 5.3 out of with a 6.2 L92 from an Escalade. Unfortunately, after copying over most everything relevant from the 6.2 tune, I cannot get the truck to stay running without throttle. It's super easy to get to start, I just added 150% more startup airflow. It's just that after it starts up to 1300 RPM or so, it will plummet back down to 0 without throttle.
Everything is effectively stock (exhaust manifolds, stall, filter/intake) with the exception of adding a VVT Low Lift Truck cam. It?s a small cam at just 212/226 0.550/0.550 113. I was not expecting this to require much idle tuning, but apparently the E38 is more sensitive to these things than the E40 I?m familiar with. I'm using the L92 throttle body which should identical to what was on the 5.3, and so should be compatible with my pedals.
Also, I deleted DoD out of the tune and I do not have VVT enabled (or physically hooked up), so the cam should just be in the default (advanced) park position.
I have my idle RPM set to 950-850 to try and have a chance, but when it does idle, it runs between 700 and 800 RPM and will never hit 850 on its own. I would think this implies I need more idle airflow but I?m getting close to over 100% greater than stock and with such a small cam, that doesn?t feel right. I?ve also not really noticed much of a change over the last 12 lb/hr (1.5g/s) I?ve added.
I thought maybe the cryptic TB Percent Max (Effective Area) under the idle settings was limiting my idle airflow, but I moved it from the stock 2.97% up to 4% with little/no improvement.
Things I know:
At 70F ECT startup temp, I was able to get it to start and run without touching throttle using 67 lb/hr min idle air at 800 RPM. It was undriveable though as it would die after touching the throttle.
At 100F, it required throttle after startup to stay running using 83 lb/hr min idle air. BUT, after it warmed up, it was driveable and drove reasonably well with no stalls and would idle fine on its own when coming to a stop. It would not hot re-start however.
At 190F startup, I had to have 92 lb/hr of idle air for it to start and stay alive without pedal. After cooling down, to 70F it won?t start and stay alive though.
So, a consistent theme in 10+ hours of startup tuning is that approximately 2-3 seconds after starting cranking, it?ll be at about 1000 RPM?s and then the throttle % goes from 10% to 7% in 0.01s. Then the RPM?s come crashing down till it dies. No amount of idle air or throttle PercentMax prevents this. I was thinking that maybe it was the adaptives, so I turned off proportional and integral, and it still does the exact same thing. I thought maybe it was the 8s long startup airflow table which tapers off to lower airflows, so I set it to constant for those 8s and it still does the same thing.
In looking at what I?m doing when I ?keep it from dying? with the pedal, I?m essentially holding the throttle at 9%. So how do I keep the damn throttle from not going below 8 or 9%? Because apparently min idle air does not do it.
Latest Tune and Log attached. Here I tried disabling proportional and integral throttle adjustments thinking that was dragging my throttle down - without luck. Any other ideas what might do this?