Cold start issues with low compression and High Octane

[kyotey1693]

I'm pulling my hair out here. I'm still new to tuning. I've successfully tuned a few vehicles at this point but I'm still lacking in the experience department. This truck was originally a LQ4 6.0 but now a 5.3 with 317 heads and -2cc pistons, BTR4 truck cam, running 93 octane. Depending on who's calculator I use, this puts the CR at somewhere between 8.9-9.3:1. Still running stock 6.0 intake, injectors, MAF, etc. Not the ideal combo but he's planning to add boost in the future.

When the weather was decent I got the MAF and VE tables lined out with the WB and I'm pretty pleased with how it runs overall. I think the VE map looks odd but the correction factor is within 3% everywhere so I feel pretty confident in the numbers. I was about ready to start tweaking the timing some and then we got hit with some cold weather and this thing won't start to save it's life. Even with me working the throttle. We're in the teens temps wise. When I started tuning it we were in the 40-60's and the truck would light off fine.

So I've read a lot of things on here about stuff to try and I think I've tried nearly everything and it doesn't seem like I've made much progress. I've added a ton of startup air, quite a bit of timing and FA cranking fuel with fairly little change. I've tried adjusting the cranking VE to match the actual and still not much progress. Over the past few days I've tried increasing and decreasing each on these parameters to see if any really make a difference, I've tried creeping up in small amounts or making large changes just to see if anything shows and I really cant get any good feedback about what is happening. I'd like to see how the truck starts on 87 octane but I feel like I should be able to make it start with 93 even with it's low CR. I've read most people say to leave Temp Bias alone. I prefer it to be based more on IAT anyways but will this help? One thing I haven' tried is disabling the MAF or VE and starting the truck off one or the other. Is that worth a shot to rule them out of the equation?

2 things I have noticed that seem odd to me, regardless of what changes I make to the tune, it seems like the "sweet spot" for getting it to start is to hold the throttle right around 40%, anything more or less and I barely get it to puff. The other thing that is strange to me is the truck won't maintain it's own idle until roughly 100ECT. Almost like something isn't enabled until it gets to that temp. Or possibly 30IAT, it seems like 1 or both of those parameter have to be met before it will maintain idle on it's own without me giving it some throttle.

I've attached the most recent tune and log file. There's some ugly stuff in the tune regarding startup air and fuel but that's the closest thing I've been able to come up with to get it to start. I had it running a couple times before this log so that's why it's a little warmer but each time it has needed 40%TPS to start and then a little to stay running.

I'd appreciate any suggestions.
FT.R3.8 terrible cold start, needed 40%TPS wont hold idle till 100ECT.hpt
FT.R3.8 terrible cold start, needed 40%TPS wont hold idle till 100ECT.hpl

[kevin87turbot]

I've a few with a leaky injector or two that would cause similar symptoms. The cold weather would exacerbate the issue since you obviously have way more cranking fuel at cold temps.

[kyotey1693]

That's definitely a possibility. These are his original injectors with a ton of miles on them. I'll check into that. Thanks!