LQ4 Tune Question

[YungTyph]

https://log.tunezilla.com/s/pMgoXXUT Here is the latest idle log I have here. Still working out the table with a fresh XDF/bin combo.

With a new tune all together based off the 04 Silv 6.0L Manual trans from above I have a pretty solid start. The idle is still a bit funny, especially when working up to temp... Wondering what a throttle cracker looks like without a VSS in a manual, just based off air/vacuum? Have reduced my idle timing correction to a pretty flat +/- 5 deg.

Wondering if I should modify the switch voltage on the O2 sensors as it seems to be really top heavy on rich readings, potentially causing some issues?

Going to keep modifying airflow, spark and timing until she seems happier, but would love any input.

[YungTyph]

Update for those following along from home.

Edited the tune a bit- modified idle airflow & spark values, changed idle to 900. Seems happier, but around a minute or two into each start my O2 sensors drop off and I start running really lean. Set O2 sensors to switch at 700 mV now to see if they were reacting late, but that doesn't seem to be the issue.

https://log.tunezilla.com/s/gasngAJB

This log starts around 1min30sec after starting the car. stumbling and odd idle seems more time based than temperature based now. Wondering if I need to start looking into idle decay settings. Screenshot to show the full context, TuneZilla doesnt love longer files it seems...

[2xls1]

What injectors are you using and what is the fuel rail type? Dead head or vacuum referenced with a return? You are only changing the IFR table. There are other tables that need to be changed with different injectors. There are a lot of things I see that aren't quite right too. Guessing this is a swap vehicle. You should list as many details of what the build is for good help with it.

[YungTyph]

What injectors are you using and what is the fuel rail type? Dead head or vacuum referenced with a return? You are only changing the IFR table. There are other tables that need to be changed with different injectors. There are a lot of things I see that aren't quite right too. Guessing this is a swap vehicle. You should list as many details of what the build is for good help with it.

Yikes, thought I had this one pretty good. Its a returnless LS2 style intake manifold and fuel rail. Stock LQ4 bottom end, Elgin E1840P, LS2 Heads, upgraded springs and pushrods. Not running EGR (but zeroed out for my wideband) and not running evap. Heads vent to atmosphere/TB directly, may eventually do a catch can.

I matched the IFR to a known LS2 GTO table, but was unaware there were others... Would love to learn what else needs updated!

[2xls1]

Injectors - Offset vs Volts, Short pulse adder, Short pulse limit, Minimum PW. Some of those tables won't transfer directly from a GTO file because the table labels are different. And just venting crankcase to atmosphere is not a good idea. You should have some kind of PCV system. What about the exhaust system? You're not running open exhaust close to the O2 sensors are you? Sounds like a lot of the problems are starting when it switches to closed loop. I can't make much sense from your logs.

[YungTyph]

Injectors - Offset vs Volts, Short pulse adder, Short pulse limit, Minimum PW. Some of those tables won't transfer directly from a GTO file because the table labels are different. And just venting crankcase to atmosphere is not a good idea. You should have some kind of PCV system. What about the exhaust system? You're not running open exhaust close to the O2 sensors are you? Sounds like a lot of the problems are starting when it switches to closed loop. I can't make much sense from your logs.

Good to know, will investigate a comparable bin if I can find one... After a few seconds of thinking, I believe you are right on the money with the PCV potentially being an issue. Certainly seems to cause excess condensation in my oil system. Exhaust runs for a decent bit after the headers, merges and runs back into a Y pipe then dumps under the car, I think plenty of back pressure.

I am with you, closed loop seems to hit the car like a freight train. I will continue to dig and see if I can implement a simple PVC in the meantime.

[2xls1]

It's not back pressure that is needed. It is you don't want O2 sensors anywhere close to open exhaust so outside air doesn't effect their reading oxygen only in the exhaust. This means absolutely no exhaust leaks anywhere near the O2s. Especially upstream of them and within a couple of feet downstream.