Guys Tuning 0411s step inside

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L31MaxExpress

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I have had an overly rich startup since the day one on the 97. Got a little better with the 0411 swap. I recently datalogged a startup with the coolant temp in the 50s and noticed that the 0411 post startup air fuel ratio was commanded at 3.5:1 and it stayed there for about 7 seconds before leaning out to the normal open loop air fuel ratio tables values. I downloaded 3 seperate 0411 van tunes including one from 2001 and two from 2002. One 2002 and the 2001 were 4L80Ee vans and the other 2002 a 4L60E van. I thought perhaps what I was looking at was non-GM tuning in the base file I had. Turns out it very much was how GM tuned the startup. From my experience with carbureted engines, it acted like the choke pull-off was not functioning. I set out to fix it. After reading the couple of posts I found with similar issues on cammed LS engines I had a little bit of direction to start on. I ended up multiplying both the After Start Decay Delay and the After Start Enrichment Multiplier by 0.25. I tested it out this morning after an overnight cool soak. The result is it now richens the mixture much less and only for about 1-2 seconds after the engine actually fires. It settles almost immediately to a commanded 10.8:1 air fuel ratio and the wideband closely matches. I hope this helps someone as it has always plagued me. The black box was so bad it would sometimes flood the engine on the first starting attempt. It would not start unless you pinned the throttle to the floor and cranked it over for 5-10 seconds. When that happened, it would generate a grey cloud of fuel smoke when it started.

After Start Enrichment Delay Stock

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After Start Enrichment Delay Modified (Stock Multiplied by 0.25)
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After Start Initial Adder Stock (The number gets added to the Open Loop Air/Fuel Ratio multiplier)

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After Start Initial Adder Modified (Stock Multiplied by 0.25)
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I data logged a cold start this morning with the wideband already pre-heated. Air Fuel ratio was about 0.72 lambda or about 10.15:1 immediately after it fired up.

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L31MaxExpress

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The second problem that has plagued the tuning for years has been fuel trims around idle that shift drastically with intake air temperature. On a cold start the short-term fuel trims become active in about 60-90 seconds and start trimming the fuel delivery. When both the coolant temperature and intake air temperature are roughly equal the fueling was fairly steady. As the coolant temperature started to climb and the commanded open loop air/fuel ratio leans toward stoichiometric the fuel trims would start to drift higher showing a lean condition. It would continue to lean out the higher the coolant temperature climbed. Once the thermostat opened and started heating the radiator and thus the intake air temperature the fuel trims would slowly start to decrease. Once the IATs were in the normal range where I had tuned the fuel map on the road the fuel trims would sit where they belonged. When the engine idled and heat soaked the fuel trims would dip indicating a rich condition. What I ended up doing was messing with the IAT Bias value. I had taken a stab at adjusting this what seems like 50 times over the years, with no real knowledge out there on how it works. I eventually plugged in the IAT Bias values from a newer 2004 6.0L van as the LS engines seemed to have less of a swing from what I had noticed tuning them. I used the Express van LS bias because my van has the same air cleaner assembly and placement. However, I wanted to get the heart of it and actually correct the fueling swings. I finally sat down and looked at what was physically causing it. Both the 02 and 04 bias values are heavily biased toward the engine coolant temperature value at idle and low airflow. In fact, on the 02 file the idle temperature compensation came almost entirely from the coolant temperature sensor with almost zero influence from the IAT. Turns out GMs tuning did not even use the IAT reading at and around idle to help calculate air density and thus the fueling swings all over the place as the actual air density getting to the cylinders changes. I took a stab in the dark at it and drastically reduced the values at idle and lower flows. I left the mid-higher flows where the fueling seemed to be stable alone. I data logged the engine at idle yesterday morning and this morning from a cold start through fully heat soaked. Yesterday the average fuel trims had a variance of 9.4% from highest to lowest. This morning the variance had reduced to 5%. Now that I know what is causing it; I will mess around with it more after the intake swap is done. For the little time this will be together and running with the current intake it is good enough for me. I hope this also helps someone as the information on this is practically nonexistent as well.

Stock 2002 350 Express
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Stock 2004 6.0L Express
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Custom IAT Bias (First Attempt)
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Old 2004 Express IAT bias average fuel trims vs MAF frequency
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Custom IAT Bias average fuel trims vs MAF frequency.
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RichLo

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I cant wait to get HP tuners for my 3.8sc Fiero and pick your brain next year!

Considering doing a 0411 swap on my 97 454 so I can play around with that also.

Dumb question but how do those credits work with HP tuners? I couldnt find what they do, if they are needed and how many I need to buy if they are needed.
 

L31MaxExpress

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I cant wait to get HP tuners for my 3.8sc Fiero and pick your brain next year!

Considering doing a 0411 swap on my 97 454 so I can play around with that also.

Dumb question but how do those credits work with HP tuners? I couldnt find what they do, if they are needed and how many I need to buy if they are needed.

I am assuming the new interfaces come with credits. I know the new credits are universal credits. For this generation of GM PCM it takes 2 credits to tune each PCM. 1 credit is $49.95. When I bought my MPVI Pro interface back in about 2009 it included either 6 or 8 credits, forget which. When it comes time to license the file you are using, you have the option to license that one vehicle or an unlimited number. For most older operating systems that run on a black box, P01 or P59 requires 6 credits to upgrade to unlimited. For most of the newer operating systems that run say an E38 or E40, it requires 12 credits. I have unlimited on two operating systems. As I licensed PCMs that I tuned, the upgrade path requires fewer credits to where eventually it is very affordable to just upgrade that operating system to unlimited.
 
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BeXtreme

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I cant wait to get HP tuners for my 3.8sc Fiero and pick your brain next year!

Considering doing a 0411 swap on my 97 454 so I can play around with that also.

Dumb question but how do those credits work with HP tuners? I couldnt find what they do, if they are needed and how many I need to buy if they are needed.
I've been thinking about getting HP tuners also. Currently I just use an OBDXProVT device and TunerPro RT for modifying the 0411. I use PCM Hammer or LS Droid to read/write in the vehicle and datalog. Its not the most user friendly and it takes a bit more time, but it's all free... so at least there is that.
 

L31MaxExpress

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I've been thinking about getting HP tuners also. Currently I just use an OBDXProVT device and TunerPro RT for modifying the 0411. I use PCM Hammer or LS Droid to read/write in the vehicle and datalog. Its not the most user friendly and it takes a bit more time, but it's all free... so at least there is that.
I use Universal Patcher as well.
 

Supercharged111

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Personally I've been living with a number of quirks with my setups, but began making real progress last year in dealing with said quirks. I'd have to log myself to see if my idle is doing the same as yours, but I bet it is. Sometimes it idles smooth as glass and sometimes it feels kinda lumpy. I'd long chalked it up to some intermittent electronic component or something else as it's persisted over so many hardware changes. Seasonal PE AFR swings were one of my biggest annoyances. Since changing to MAF only that seems to be gone. Lean starts were also persistent, we'll see going forward if that's still a thing after the last couple days. You've given me some food for thought that's for sure.
 

Reluctanse

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0411 swap is done and I have what I'm going to call my "1.0" tune finished. But it is nothing more than a starting point, that lets the truck run and drive.
My wideband O2 sensor will be here next week.
Some good info here, once I have visibility with the wideband I'll be doing some logging and tweaking based on this info - thanks!!
 

that97hoe

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0411 swap is done and I have what I'm going to call my "1.0" tune finished. But it is nothing more than a starting point, that lets the truck run and drive.
My wideband O2 sensor will be here next week.
Some good info here, once I have visibility with the wideband I'll be doing some logging and tweaking based on this info - thanks!!
hey you guys i’m sorry this is probably a dumb question but i have all the pin outs for a 0411 swap, it’s super rare to find an express van or savannah out here where i’m at in the pick and pull, and was wondering if that’s basically the only option for finding one, and what year i would need to find for a 0411 swap on a 1997 tahoe
 
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