Transient Mass Gain help

[schiavonske1013]

I have a 2005 Silverado, 216/224 .585/.585 115+5 cam, 243 heads, otherwise stock 5.3, lsa blower with 2.45? pulley. I?ve been having problems with leans spikes. Any time I let off the throttle completely, and then first get back on it I get a spike. If I really ease on I go 15.5-16, stabbing it any harder I used to see anywhere from 17 all the way up to 20 on the wideband for a brief second before it caught itself. You could definitely feel it, and anytime the truck is below operating temp it is so bad it actually almost stalls. I seem to have my ve table dialed in correctly, I am running 2bar speed density, maf not even plugged in.

Everything I?ve read says transient fuel. However I noticed I only have the ?mass gain? table which is some type of multiplier based on airflow. I seem to be missing at least one other table. Can someone enlighten me on how to effectively use this table seeing as I have no maf to actually tell what airflow rate is when it happens. Like I said it is just brief, steady state ve numbers seem to be good.

I?ve been bumping the table up by massive percentages and I?ve seen some progress, the spikes are still there just to a lesser extent, max I see now is 17, however now I?m seeing it go rich when letting off, I assume as I?ve been bumping up the whole table, not just specific areas.

Is there a better way to really dial this in? The spikes under operating temp are still there as well, and it still feels like it will stall if I don?t touch the gas with my pinky toe only.

I am not at my computer or I?d post log and tune. I can later.

[kingtal0n]

I'm also trying to figure out how to do these things in Gen3 computer, I have a 411
The only settings I see is "transient fuel" and "Impact from wall" , I tried reducing them but still have some major rich when lifting from the throttle.

In for more details

[schiavonske1013]

Right I am a bit lost even as I read other threads. I can’t find an explanation of the actual effects of the mass gain. I found by going through the repository, it appears that around 03/04 the ability to see the other impact factor table disappears.

[HackAbuse]

Right I am a bit lost even as I read other threads. I can?t find an explanation of the actual effects of the mass gain. I found by going through the repository, it appears that around 03/04 the ability to see the other impact factor table disappears.

I'm sure other people have had better success, but personally the last year trying to nail down transient fueling on my setup has been a giant series of educated guesses. I still don't have a full grasp on the subject, but fueling and drivability are 100x better than when I started and continue to improve slightly week after week

[schiavonske1013]

well i'm still lost, i have played around with the mass gain and it seems to help in some areas but not in others, i can get it to the point where light throttle transitions are okay, but quickly getting on it with anything other than mild pressure causes a 17-19 afr spike, it's not a false reading as you can hear it stumble. i played with injection timing a bit, someone said try lowering it down due to the cam overlap, and it made idle afr stay steady, but it make big throttle transitions seem the same or worse. i attached 2 tunes and logs, one with stock injection timing, and one with it brought down a bit. v37 is injection timing changed, and 19-24-13 is the associated log and v38 is stock injection timing and 19-38-11 is the associated log for it.

in both i turned the transient back to stock. for the heck of it i attached my injector data too. it's tough logging areas where it spikes in a graph as it is so quick. it is infinitely worse when not at full operating temp, it will shoot up past 20 afr and almost stall. i am at the point of giving up and paying the local ls engine performance shop to try their hand at it.

does anyone see anything to edit?

[HackAbuse]

Start logging Intake Valve Temperature and pay VERY close attention to where those lean spikes are. This isn't something you're going to conquer in a day, a week, or even a month. I've been dialing in mine for over 2 years and 387 different calibrations in the last 12 months alone (I keep copies of every single iteration.)

[kingtal0n]

The log shows up to 175kpa- 12psi of boost is that right?

The timing map doesn't make a lot of sense. It drops to 11* for 0psi then 14* by 12psi, ridiculous IMO. If this is pump fuel the timing is seems a bit too much.
I see some serious KR in some place(s) too.

As to this fueling issue. I can't help with transients because I have no idea yet how it works either and your version is different than mine.
However, I have alot of experience hiding issues with transient fueling. Simply enrich the VE basemap in the areas where you are first experiencing a lean spike. Its ok for the VE table to go high in the regions where it zings through quickly- as with a blower will tend to do. In other words, what happens to the VE map when you stab the pedal? How long does it stay at 0psi or 2psi? Not very long right. The boost tends to shoot directly through those regions so fast it has very little influence on anything. So this is why I say to simply enrich that spot, you won't spend much time there so it wont matter if its "too much" but it will act like a mini "pump shot" of fuel.

Its just a bandaid so you dont ruin the engine while you figure the rest out.

ex.
80
82
84
86
88
105
95
92
94
96
etc It will act as a transition pump shot, or as a 'derivative gain' if you will.
Also make sure you log the wideband faster than 500ms. More like 100 or 50ms to catch the exact spot it goes lean.

One more thing. I see voltage from the alternator drop out randomly. It sits 14v for a while then suddenly 12v for a couple seconds. there is a map that correlates voltage with injector delay so you might need to enrich the injector delay map where the voltage is low.

[schiavonske1013]

So what parameters would the intake valve temp assist in tuning? Does this go along with the mass evaporation tables?

I have had some success pumping extra fuel into the ve table to compensate, issue I’ve run into is it seems to hit those areas at times when the converter is locked while cruising on the highway. The voltage drop is due to a recent issue with the alternator, it’s been going on since before that. Wideband logs at 20ms, I have the uego which supposed reads that quickly. I didn’t develop the timing table myself, but I will have to look closer at knock retard, it’s weird the table shows all zeros?

Thank you both for the suggestions.

[kingtal0n]

I have had some success pumping extra fuel into the ve table to compensate, issue I’ve run into is it seems to hit those areas at times when the converter is locked while cruising on the highway.

From about 10kpa to 60kpa dont enrich anything abnormally. That way it never hits a rich cell while cruising. While cruising if you tip in or out slightly it won't go very lean or rich during a transient that way.

The real issue and safety concern is from 60kpa+ where you need extra fuel or it could knock.

[schiavonske1013]

Alright I’ll keep working it that wat for now. Trying to dial in the mass gain has only gotten me so far.

[schiavonske1013]

How is everyone dealing with the os versions that only allow the Goan adjustment? Just guessing? I don’t have a maf as I maxed it out on my old setup so I have no idea what airflow everything occurrs at. I have no access to the tables that base off of ect and map.

[HackAbuse]

Ah yeah I never noticed that on P59 before. Not sure how that works then

[schiavonske1013]

Right so I’m not sure the gain options are actually effecting since there’s no other table to set the gain on

[HackAbuse]

Right so I?m not sure the gain options are actually effecting since there?s no other table to set the gain on

They definitely do. I added some to the gain on a P59 in an 04 GTO a couple months ago and it made a clear difference in response

[schiavonske1013]

Right it’s having an effect, just not sure how to dial it in other then just randomly adjusting certain sections and seeing what happens. Can you clarify what you table you are modifying with the intake valve temp reading? I’ve never seen that mentioned.