Afr cant reach commanded

[LS ROB]

What is the best way to get the AFR to follow commanded? At WOT, I'm commanding 12.13 but only getting 12.5ish. MAF is already showing rich as well as the VE. The only way i've been able to obtain target AFR is to leave MAF a little lean up top so that it carries over into PE. You guys got any tips on how to effectively dial in WOT? Tune and log attached.

Thanks.

driveability (631-582) 1.9.hpt
fr wrk.hpl

[07GTS]

looks like its following the VE airflow, should be able to add to the VE to correct it, also disable LTFT and reset to zero in scanner then see if its better with just the STFT

[LS ROB]

I tweaked the VE and MAF a bit and made a small WOT pull. I done this before I seen that you replied. I will try adding 3% to the VE and disabling the LTFT's next time i give it a go.

I thought whenever you go WOT, that LTFT's are used, no? What scenario or issue would cause commanded to follow VE and not the MAF if that's what is happening?

driveability (631-582) 2.0.hpt
driveability (631-582) 2.0.hpl

[GHuggins]

Since it's jumping up like it is in the VE table only at wot and this is assuming the rest below that is right then most likely your inj timing is too retarded. You can try reducing it by 10 at a time in the higher rpms in the boundary table where you're experiencing this issue to see if fueling richens up. Try to keep it smooth. Anytime there is a sudden change in rpms it will reference the VE table, but as we've recently learned it will read MAF 100% above 4000 rpms.

[LS ROB]

Awesome. Thanks Greg! I'll give it a go next time I fiddle with it!

[LS ROB]

Lowered the boundary and kept it smooth. While the trims showed slightly rich, the wideband is still showing leaner than commanded. Attached is the tune and log in case someone sees something i'm overlooking. Wideband is AEM 30-0334 X-Series OBDII.

driveability (631-582) 2.2 boundary exp.hpt
drivability boundary exp.hpl

[GHuggins]

It's going to look screwy, but it all works together. Give this one a try. Then keep this in mind too. As we recently discovered everything above 4000 rpms is MAF 100%.

[LS ROB]

Thanks Greg. I'll put those settings in my current cal, flash it and see what happens. Regarding the MAF; Do I want all 0's at WOT or is it ok to leave it rich if that's what it takes to reach commanded? Correct me if i'm wrong here. My understanding is that whenever you are reading 0's then the MAF is dialed in? If so, then fattening it up some should help pick up a little more torque? I know the AFR has to be reasonable.

[SiriusC1024]

0's means fuel trims haven't populated there. PE kicks in and it goes into OL. No problem bumping MAF up looks like it needs it anyway from the curve.

[07GTS]

As we recently discovered everything above 4000 rpms is MAF 100%.

is this only if the throttle is kept at wot ? i can only assume that if the throttle is released and then punched back to wot the vve will be used above 4k for that transition ?

[blindsquirrel]

Can you please post a brief summary of your build when you start a thread asking generic questions like this? I can only ever remember that it's LS7 something and I've been caught out before, giving generic suggestions to generic questions when it turns out generic doesn't really apply to your situation and then I look like the idiot.

[TheMechanic]

It's going to look screwy, but it all works together. Give this one a try. Then keep this in mind too. As we recently discovered everything above 4000 rpms is MAF 100%.

Got a couple ??'s for you on your EOIT's.
What was the reasoning for this adjustment? "Boundary" and "Normal".
Looks like "Normal" only goes to 4,096. Does this project out the last 25 degrees in the 4,096 column to higher rpms?
What typical engine mods do you do this for? Any exceptions to this rule as in going further if you have "X" mod?
Sorry for so many questions.

[GHuggins]

Got a couple ??'s for you on your EOIT's.
What was the reasoning for this adjustment? "Boundary" and "Normal".
Looks like "Normal" only goes to 4,096. Does this project out the last 25 degrees in the 4,096 column to higher rpms?
What typical engine mods do you do this for? Any exceptions to this rule as in going further if you have "X" mod?
Sorry for so many questions.

I went after inj timing because of his VE table. I know he's spent a lot of time dialing it in so I'm assuming it's really close if not spot on. In his VE table it ramps up quite a bit under full load. May just be his cam, but the majority of the time it winds up being fuel burn. If you look at his last posted logs his EQ errors start increasing - albeit not much - right at 4000 rpms. He's also still running the rpm table populated with values and right at the 4000 rpm point it goes from super advanced to really retarded as it's just using the boundary table at that point. With his new tables I used both and left about a 12 degree downstep. He can play with it more to smooth it out even better.

The table for boundary he was running is one of mine. Usually good for torque. Doesn't mean they all like that though and often enough the LS7's like advanced inj timing. They are VERY advanced from factory with their stock cams.

What I've found is when they're overly retarded you wind up with too much "raw" fuel in the chamber and this raw fuel won't burn the best. This is when it's better to test it with advancing and retarding alike. I used to go by valve events, but fuel spray and atomization starts coming into play more so than the events do especially when you start figuring in back pressure and piston suction motion.

Now I go off of data and what the engine is wanting. I make up advanced and retarded tables off of what's currently in them and then tell the owners to get the engine hot then flash the first, log for 20 minutes, do a quick stomp free rev all while in park and then flash the next file right then and do it again. Once I get the logs I look for which has the most negative trims and the richest EQ error during the stomp. I also use a tapering boundary with both where one is more neg and one more positive in the same manor. This lets me know which way I need to shift and work things. Customers often also tell me things like the idle settled better on this one or it felt more peppy on this one or it started and idled better on this one vs the other. There's a whole lot in injection timing for base engine settings and fixing problems.

I've got a customer right now going through this. He's been having bad smell issues and idle rpm dipping from his previous tuners (quite a few in fact). We've already found that his likes it advanced. Fires up better and idles better. He's going to be testing "more advanced" and "super advanced" tomorrow His O2's are also horrible among other things I'm just noticing in his idle logs.

I haven't tried it, but Cringer's inj timing tool is supposed to shape it something like this as well.

[LS ROB]

0's means fuel trims haven't populated there. PE kicks in and it goes into OL. No problem bumping MAF up looks like it needs it anyway from the curve.

Thanks for taking a look and the suggestion Sirius.

[LS ROB]

Can you please post a brief summary of your build when you start a thread asking generic questions like this? I can only ever remember that it's LS7 something and I've been caught out before, giving generic suggestions to generic questions when it turns out generic doesn't really apply to your situation and then I look like the idiot.

No problem Sir. That is my fault. I keep forgetting that most of you guys do this stuff all the time and deal with countless combinations. I have updated the post with build details.

[LS ROB]

I went after inj timing because of his VE table. I know he's spent a lot of time dialing it in so I'm assuming it's really close if not spot on. In his VE table it ramps up quite a bit under full load. May just be his cam, but the majority of the time it winds up being fuel burn. If you look at his last posted logs his EQ errors start increasing - albeit not much - right at 4000 rpms. He's also still running the rpm table populated with values and right at the 4000 rpm point it goes from super advanced to really retarded as it's just using the boundary table at that point. With his new tables I used both and left about a 12 degree downstep. He can play with it more to smooth it out even better.

The table for boundary he was running is one of mine. Usually good for torque. Doesn't mean they all like that though and often enough the LS7's like advanced inj timing. They are VERY advanced from factory with their stock cams.

What I've found is when they're overly retarded you wind up with too much "raw" fuel in the chamber and this raw fuel won't burn the best. This is when it's better to test it with advancing and retarding alike. I used to go by valve events, but fuel spray and atomization starts coming into play more so than the events do especially when you start figuring in back pressure and piston suction motion.

Now I go off of data and what the engine is wanting. I make up advanced and retarded tables off of what's currently in them and then tell the owners to get the engine hot then flash the first, log for 20 minutes, do a quick stomp free rev all while in park and then flash the next file right then and do it again. Once I get the logs I look for which has the most negative trims and the richest EQ error during the stomp. I also use a tapering boundary with both where one is more neg and one more positive in the same manor. This lets me know which way I need to shift and work things. Customers often also tell me things like the idle settled better on this one or it felt more peppy on this one or it started and idled better on this one vs the other. There's a whole lot in injection timing for base engine settings and fixing problems.

I've got a customer right now going through this. He's been having bad smell issues and idle rpm dipping from his previous tuners (quite a few in fact). We've already found that his likes it advanced. Fires up better and idles better. He's going to be testing "more advanced" and "super advanced" tomorrow His O2's are also horrible among other things I'm just noticing in his idle logs.

I haven't tried it, but Cringer's inj timing tool is supposed to shape it something like this as well.

Thanks again for the informational explanation Greg. My problem is, I get things looking and feeling really good and then think; " I wonder if I could get it perfect?" Then of course, sometimes shoot myself in the foot. LOL But its a fun hobby for me and i'm always learning something new from you guys, so i really appreciate that.

[LS ROB]

Since it's jumping up like it is in the VE table only at wot and this is assuming the rest below that is right then most likely your inj timing is too retarded. You can try reducing it by 10 at a time in the higher rpms in the boundary table where you're experiencing this issue to see if fueling richens up. Try to keep it smooth. Anytime there is a sudden change in rpms it will reference the VE table, but as we've recently learned it will read MAF 100% above 4000 rpms.

So, I was thinking that when the trims hit 0, it meant that the fueling was dialed in. I re-read this and decided to give the MAF the fuel needed to achieve commanded AFR. It worked. Simple. Also, I am still running the Boundary settings you hooked me up with a while back. It was as simple as just needing more fuel and ignorance on my part.

I was hoping to get some opinions on the HP & TQ numbers. I use them as another "tool" to see what effects my changes make. Anyone have any info on what I could expect out of this combo?


up.hpl

[GHuggins]

Did you check the newer settings to see if it made it go any richer or felt any different? Goal is to have fuel timing optimized so it doesn't require as much and better atomizes the fuel for a more complete burn. If it didn't change anything then run the previous tables.

[LS ROB]

It did richen up some . The trims went from 0.00 to -.39 at WOT.

I was going to use Cringers EOIT Asst. but whenever I go to download it, it gives me a warning that the file could be harmful to my computer. Did you get that as well when you opened it? I'm very cautious about that stuff so i reached out to Cringer and he advised it was pretty much a standard warning but i still haven't gotten around to use it yet.

drivability boundary exp.hpl

[JayRolla]

It did richen up some . The trims went from 0.00 to -.39 at WOT.

I was going to use Cringers EOIT Asst. but whenever I go to download it, it gives me a warning that the file could be harmful to my computer. Did you get that as well when you opened it? I'm very cautious about that stuff so i reached out to Cringer and he advised it was pretty much a standard warning but i still haven't gotten around to use it yet.

drivability boundary exp.hpl

That is just a warning to let you know your downloading an executable that could potentially be a harmful program. But since you are downloaded from a trusted source (Cringer) you are good to run it. Its a default warning.