IVT (intake valve temp) and commanded AFR adjustments

[NotSure]

Working on my Gen4 L94 and have a question regarding a couple of charts that make adjustments to the Equivalence Ratio based on IVT, can't remember the exact chart names right now and don't have HP on this computer. I have been chasing down VVE with the MAF disabled and it seems to be jumping around despite my adjustments. Then I found the above IVT charts and thought they may be affecting it under different conditions. However, commanded AFR is right where it should be based on the alcohol % (around 14.1 AFR at stoich, running E10). So the question is if the "commanded AFR" is taking into account the adjustments of the IVT, or is that done on the back side and not shown? I would think the commanded AFR would include these adjustments, but when the IVT is colder than 147 F (the approximate cutoff in the charts above which there is no EQ adjustment) it is still showing 14.1 commanded?

[NotSure]

Finally got back to my computer with HP installed. The charts in question are under Fuel-Open Loop/Base-Open Loop Gains-IVT Gas Gains. The others are under Fuel-Open Loop/Base-Open Loop and are Gas(Gear), Gas(P/N), Alcohol(Gear), Alcohol(P/N).. Hope that helps explain the situation.

[Ashleyrose]

Following

[95Gturbo]

I'm running into this in cold weather with a few 5th gen camaros I have tuned. At least I believe it to be so. I think it is labelled wrong...I think it is a % modifier for calculated pw, and not related to commanded eq. The issue that I am having is that the car follows my Pe on the wideband beautifully, until ambient get cold enough to effect the IVT...then it starts hitting 0.2-0.4 afr richer than target. It isnt a big deal, but I am cautiously going to adjust this and see how it goes.

[07GTS]

the OL IVT table is a multiplier, u also have the charge temp multiplier bias table that can be used to more follow iat readings or coolant temps and anywhere in between, may help

[NotSure]

Being a multiplier makes sense, though I still wonder if the "Commanded AFR" PID is pre or post multiplier adjustment. My commanded AFR seems to be spot on WITHOUT any IVT multiplier when I am in a cooler IVT range when it would be affected. So, say you are commanding 14.68 stoich, and the "commanded AFR" PID shows 14.68, but your IVT is say 100F and is in the range for a multiplier to be in effect, would the commanded AFR show the resulting adjustment or is it done on the back side?

[07GTS]

i havnt really done much testing with it but i think its to correct the OL commanded based on IVT so i dont think the commanded changes only the fuel based on the IVT temps sorta like an offset, think if u were at commanded 1.0 and ur fueling was spot on then if u went in and multiplied IVT by say 50% see if the fuel is still spot on or changed by the multiplier amount then u will know how u have to change it

[NotSure]

Looking at the cal I found this oddity in the IVT to ECT table, there is a spike in the EQ multiplier between IVT of 190 and 262F. It may make sense to richen it at higher IVT for cooling or some reason, but why drop it back off at higher IVT's? I looked at a couple of other cals (E38 Camaro, etc) and they all have some sort of odd spike or drop in these figures but in different locations. I am wondering if it was just an error on GM's part? IVT spike.PNG

[NotSure]

Here is an example from a stock 2013 Camaro, which has the same long block content as my Yukon. Odd jump but different location. The 3D graph looks horrible.

13 Camaro IVT spike.PNG

13 Camaro IVT spike 3d.PNG

[07GTS]

might be a bit of enrichment for hot start but as soon as u go back in CL it wont matter whats in that table, unless ur driving round in OL all the time

[NotSure]

I am trying to tune the VVE and the MAF via wideband while in OL. So I don't know how much this is throwing of the AFR error calculation.

[07GTS]

just make all the operating temp OL areas after say 50c ect and 80c ivt above all 1.0 so all normal driving will be same till its dialed in, ive been driving round like that OL for years, if operating temps are fine after u have dialed it in then u find the lower temps are off u can adjust those areas to suit using the OL tables