lean area around 2500ish rpms-2014 ctsv

[smokeshow]

Thanks for taking the time to help me out, I appreciate it. I didn't realize that you posted some new o2 settings to try. I will give that a shot to see what happens

I'm fairly certain this is mostly a transient fueling issue. I've seen it before in mild form on dozens of vehicles but none so extreme as the LSA blowers, particularly with aftermarket injectors. I've mentioned it in detail here and elsewhere in the past, but essentially what you're up against is an injector that doesn't spray directly at the intake valve. To my knowledge only the actual LSA/LS9 injector has the proper axial offset to prevent this problem. I did have a lot of success with the ID1050x injectors I ran in the LSA though - gotta hand it to them for the quality. Other injectors were absolutely undrivable. I might try adjusting the transient fuel model to clean up those rich/lean excursions.

That much would explain the movement in the fueling during shifts. But it looks like you have something else going on as well. Can't be too sure with the data so far but it seems like the dynamic air zone transition at 2500rpm is clearing out the VE correction factor from entering steady state airflow (maybe coincidence?). Ignoring the VE correction in steady state is normal operation for the software, but the filter for the VE correction factor is too sensitive to tolerate poor steady state detection from not calibrating the steady state detection algorithm...but most of those variables, the filters and steady state definitions, aren't available to edit. They aren't consistently available in HP Tuners, even among the same controller in different applications.

Anyway, figured I'd share. Definitely look at that transient fueling though.

[sgod1100]

I'm fairly certain this is mostly a transient fueling issue. I've seen it before in mild form on dozens of vehicles but none so extreme as the LSA blowers, particularly with aftermarket injectors. I've mentioned it in detail here and elsewhere in the past, but essentially what you're up against is an injector that doesn't spray directly at the intake valve. To my knowledge only the actual LSA/LS9 injector has the proper axial offset to prevent this problem. I did have a lot of success with the ID1050x injectors I ran in the LSA though - gotta hand it to them for the quality. Other injectors were absolutely undrivable. I might try adjusting the transient fuel model to clean up those rich/lean excursions.

That much would explain the movement in the fueling during shifts. But it looks like you have something else going on as well. Can't be too sure with the data so far but it seems like the dynamic air zone transition at 2500rpm is clearing out the VE correction factor from entering steady state airflow (maybe coincidence?). Ignoring the VE correction in steady state is normal operation for the software, but the filter for the VE correction factor is too sensitive to tolerate poor steady state detection from not calibrating the steady state detection algorithm...but most of those variables, the filters and steady state definitions, aren't available to edit. They aren't consistently available in HP Tuners, even among the same controller in different applications.

Anyway, figured I'd share. Definitely look at that transient fueling though.

Thanks for chiming in Smokeshow....I haven't even looked at the transient fuel tables at all since I started teaching myself how to tune (going on about 2 years)..could you point me in the right direction for what tables in the transient fuel tab to possibly adjust and what to look for? I have heard that the LSA injectors are the only ones that spray directly on the intake valve. It would also make sense it's an injector/transient issue due to the fact that after i install them is when I started feeling this lean bump. I just thought i needed to tweak the maf, but that was not the case It's just crazy for me to think how many guys have id850s installed and no one else has this problem but me... thanks again

[sgod1100]

i have tried so many combinations of 02 sensor settings and really haven't got to the root cause of the actual problem....driving me insane

[smokeshow]

Thanks for chiming in Smokeshow....I haven't even looked at the transient fuel tables at all since I started teaching myself how to tune (going on about 2 years)..could you point me in the right direction for what tables in the transient fuel tab to possibly adjust and what to look for? I have heard that the LSA injectors are the only ones that spray directly on the intake valve. It would also make sense it's an injector/transient issue due to the fact that after i install them is when I started feeling this lean bump. I just thought i needed to tweak the maf, but that was not the case It's just crazy for me to think how many guys have id850s installed and no one else has this problem but me... thanks again

Your two primary knobs for transient fuel will be both of the 'Gas' tables under Impact Factor and Evap Factor. The impact table values represent the fraction of the fuel from a given injection event that will not enter the cylinder, but instead stay as a liquid in the head port. Baby steps with that one...since it is a fraction of a whole and not a detached quantity itself, adding a little too much can be way too much. The evap table represents a value proportional to the time constant of an exponential decay: it is continuously evaporating, unlike the impact factor where only a fixed amount of fuel hits the port wall. It isn't as sensitive, but good practice anyway to adjust these values little by little.

What you should be looking for on a throttle tip-in is an initial spike in the injector pulse width. The heavier the tip-in, the easier it is to see in the data. That spike is the extra amount of fuel that you have to add in advance to make sure the right amount makes it into the cylinder. If you don't have enough impact factor, the spike will show up as leanness in the wideband instead. Look at every one of your throttle tip-ins and you'll see exactly that. So you'll need to increase the value in that impact table where you are seeing the issue to account for the extra necessary fuel.

On the flip side, tip-outs will often show up as the opposite - a rich droop in the wideband. A quick decrease in manifold pressure basically sucks the fuel right off the port walls and ends up being more than you need. So the opposite must take place - give it less fuel on a tip-out. To do that, you'll still need to increase the values in that table, not decrease, since the evap factor essentially represents the rate of fuel vaporization. Keep in mind though that engines are imperfect and suffer from poor combustion during deep decel MAP/retarded spark advance maneuvers. Without a complete clean burn of the mixture, it can still show up on the wideband as leanness. And that is usually accompanied by the rich droop.

One caveat though, something I discovered when trying to get non-LSA injectors working in an LSA blower...you may run out of transient fuel before you fix the problem completely. The 'puddle' of fuel that the impact factor contributes to is clipped to 2 grams of fuel to prevent puddle models from getting too large. You can't monitor this value, but you'll know you hit that mass clip when adding more impact factor doesn't help anymore. That should be enough info to get you most of the way.

[PGA2B]

So lets say you are having a consistent 5% lean tip-in spike in the same area. Would you then add half that percentage to the Impact Factor table in the IVT and MAP that you are getting the issue? Or start smaller and work up to it?

[smokeshow]

So lets say you are having a consistent 5% lean tip-in spike in the same area. Would you then add half that percentage to the Impact Factor table in the IVT and MAP that you are getting the issue? Or start smaller and work up to it?

I wouldn't jump to the conclusion that a consistent lean tip-in in a single area is something that can be solved by transient fueling; it is something that presents issues in all areas of operation. But if the leanness and/or richness is easily repeatable, and if you've got reason to believe your TF model is off now due to your mods, then I'd definitely look into it. I validate transient fuel on every vehicle I work on because of how much it improves driveability.

[sgod1100]

Your two primary knobs for transient fuel will be both of the 'Gas' tables under Impact Factor and Evap Factor. The impact table values represent the fraction of the fuel from a given injection event that will not enter the cylinder, but instead stay as a liquid in the head port. Baby steps with that one...since it is a fraction of a whole and not a detached quantity itself, adding a little too much can be way too much. The evap table represents a value proportional to the time constant of an exponential decay: it is continuously evaporating, unlike the impact factor where only a fixed amount of fuel hits the port wall. It isn't as sensitive, but good practice anyway to adjust these values little by little.

What you should be looking for on a throttle tip-in is an initial spike in the injector pulse width. The heavier the tip-in, the easier it is to see in the data. That spike is the extra amount of fuel that you have to add in advance to make sure the right amount makes it into the cylinder. If you don't have enough impact factor, the spike will show up as leanness in the wideband instead. Look at every one of your throttle tip-ins and you'll see exactly that. So you'll need to increase the value in that impact table where you are seeing the issue to account for the extra necessary fuel.

On the flip side, tip-outs will often show up as the opposite - a rich droop in the wideband. A quick decrease in manifold pressure basically sucks the fuel right off the port walls and ends up being more than you need. So the opposite must take place - give it less fuel on a tip-out. To do that, you'll still need to increase the values in that table, not decrease, since the evap factor essentially represents the rate of fuel vaporization. Keep in mind though that engines are imperfect and suffer from poor combustion during deep decel MAP/retarded spark advance maneuvers. Without a complete clean burn of the mixture, it can still show up on the wideband as leanness. And that is usually accompanied by the rich droop.

One caveat though, something I discovered when trying to get non-LSA injectors working in an LSA blower...you may run out of transient fuel before you fix the problem completely. The 'puddle' of fuel that the impact factor contributes to is clipped to 2 grams of fuel to prevent puddle models from getting too large. You can't monitor this value, but you'll know you hit that mass clip when adding more impact factor doesn't help anymore. That should be enough info to get you most of the way.

thanks further explaining this to me as I had no idea where to start. I'll start adjusting these tables slightly and report back

[10_SS]

I was leaning towards the transients being lean also since it appears to go lean every time you come back on the throttle.

I have a whipple on an LS3, but my transient tables down low, 50kpa and lower are similar to yours, but I did richen up mine above 60-90kpa, while yours show mainly 0.13, mine are in the 0.3 range above 60-90kpa, mine is about 230% more.

I would personally make your EVAP GAS table 0.3 for your warm and hot IVT temps, assuming that is the X axis you have. I often like to make big changes for something like this to see if it actually makes a change in real life.

[sgod1100]

I was leaning towards the transients being lean also since it appears to go lean every time you come back on the throttle.

I have a whipple on an LS3, but my transient tables down low, 50kpa and lower are similar to yours, but I did richen up mine above 60-90kpa, while yours show mainly 0.13, mine are in the 0.3 range above 60-90kpa, mine is about 230% more.

I would personally make your EVAP GAS table 0.3 for your warm and hot IVT temps, assuming that is the X axis you have. I often like to make big changes for something like this to see if it actually makes a change in real life.

yeah 60-90ish is where mine is going lean too.. Did you make any changes to your IMPACT GAS table? Or just the EVAP GAS table? Or both? Making such a drastic change would you blend the adjacent cells so everything is more of a slope in profile?

[sgod1100]

well, doesn't seem like altering the transient tables (evap and impact) solved my issue. I'll admit all i did was multiply the 50kpa on down rows by 1.5 to see if any good would come of it. If you look at the log you will see at approx 48, 50, 1:00, 3:28, 3:36 sec the lean conditions still exists and seems to be a little bit worse. I'm not 100% confident though it's a transient issue as i'm not stopping on gas during those lean episodes. There may be a combination of things that needs to be done, but being the novice tuner that i am i can't figure it out. Maybe it's still the transient table and I'm just not adjusting it properly. I'm half tempted to buy new injectors to see if that solves the problem, but I really don't feel like shelling out the money unless I'm certain it will solve the problem. Anyone else that has any off the wall ideas I'm willing to try anything. Thanks guys

evap and impact transient x 1.5.hpl

[smokeshow]

well, doesn't seem like altering the transient tables (evap and impact) solved my issue. I'll admit all i did was multiply the 50kpa on down rows by 1.5 to see if any good would come of it. If you look at the log you will see at approx 48, 50, 1:00, 3:28, 3:36 sec the lean conditions still exists and seems to be a little bit worse. I'm not 100% confident though it's a transient issue as i'm not stopping on gas during those lean episodes. There may be a combination of things that needs to be done, but being the novice tuner that i am i can't figure it out. Maybe it's still the transient table and I'm just not adjusting it properly. I'm half tempted to buy new injectors to see if that solves the problem, but I really don't feel like shelling out the money unless I'm certain it will solve the problem. Anyone else that has any off the wall ideas I'm willing to try anything. Thanks guys

evap and impact transient x 1.5.hpl

With leanness on a tip-out, increasing the evap factor is the opposite of what you want to do. Its the amount of fuel that is coming off of the ports, so you've just told it you need less fuel on tip-outs now. I might start by putting it back the way it was for now and just decreasing the accel/decel ratio for right now. The odd stuff around 2500 looks like discontinuity in the VVE on zone transitions. It happens at your other RPM breakpoints as well. I might re-enable your prediction coefficients to help smooth out those transitions. And the VVE itself as well.

[sgod1100]

With leanness on a tip-out, increasing the evap factor is the opposite of what you want to do. Its the amount of fuel that is coming off of the ports, so you've just told it you need less fuel on tip-outs now. I might start by putting it back the way it was for now and just decreasing the accel/decel ratio for right now. The odd stuff around 2500 looks like discontinuity in the VVE on zone transitions. It happens at your other RPM breakpoints as well. I might re-enable your prediction coefficients to help smooth out those transitions. And the VVE itself as well.

Thanks, I'll try that and see what happens. Could you quickly explain (in stupid dummy terms for me..lol) what the accel/decel ratio table does? The above log had VVE re-enabled... 3000rpm high disable and 2800 re-enable. I thought maybe it had to do with the zone boundaries of the VVE table and possibly try adjusting those as well. Maybe not have 2500 rpm being a breakpoint? That 2500 lean spot happens in maf only mode as well.

[sgod1100]

Bringing this back to life...doe altering the transient tables alter fueling while in power enrichment? I haven't tested the transient tables too much since last time I posted here. Car went in storage for winter. Now that it's getting nicer outside I want to see if this will cure this problem that I can't seem to figure out

[sgod1100]

bringing this back yet again...so i have messed with both the evap and impact tables (increased the 100 kpa row by 2.5x and then interpolated from 50kpa on up) and yet i STILL have a lean tip in everytime i shift. It seems like anything i change in the transient fueling doesn't have an effect on this lean tip in. Every since I zeroed out my prediction coefficents i have seen this lean tip in. I wanted to keep them zeroed out otherwise i don't get proper fueling when in blended mode. Is there any other things I can try to remedy the tip in problem? ANY recommendations would be greatly appreciated

[pannetron]

Here's my guess and what I'm playing with. I think the ECU may be miscalculating transient airflow. Under Prediction Coefficients, in table 13430 Dynamic Corrected Airflow Gain, I've tried increasing the value in some cells to richen tip in and reduce the value to reduce rich tip out. I find which cells to fiddle with by looking at the zone number in the Virtual Volumetric Efficiency Table that corresponds to where the engine was operating when I want to adjust the air flow calculation. If you look at a OEM ZL1 LSA tune file, the Prediction Coefficients tables have different, specific values, unlike the "same" LSA engine in a CTS-V2. Food for thought...

[sgod1100]

Here's my guess and what I'm playing with. I think the ECU may be miscalculating transient airflow. Under Prediction Coefficients, in table 13430 Dynamic Corrected Airflow Gain, I've tried increasing the value in some cells to richen tip in and reduce the value to reduce rich tip out. I find which cells to fiddle with by looking at the zone number in the Virtual Volumetric Efficiency Table that corresponds to where the engine was operating when I want to adjust the air flow calculation. If you look at a OEM ZL1 LSA tune file, the Prediction Coefficients tables have different, specific values, unlike the "same" LSA engine in a CTS-V2. Food for thought...

hmmmm....thanks for the info. I did realize that the ZL1 coefficients are wildly different than the ctsv ones. Do you know if once these are populated will they affect WOT fueling during the blended state? did you have any success altering values in this table? I'll mess with these to see if I can get SOMETHING else to happen...lol

[pannetron]

Check your VVE zone map and compare that against a scan log, looking at RPM and MAP to figure out zone the engine was in at a particular point. The ECU may use only MAF data above the Dynamic Airflow High RPM Disable but I suspect the corrections are still used. It's all clear as mud to me, too!

[papile]

I am having the same issue with a CTS-V. I can get it on point, but it really spikes up the VVE table at around 2500 RPM. It is then hard to get before and after smooth as the spike of fuel it needs at 2500 is so high. I have ID1050x too and a stage 2.5 LT1Z cam. Did you find anything with this? It seems I am OK when on MAF it is just when I am tuning my VVE table in VE only. Could it just be that the cam drops the fueling so much for low RPM and it really ramps up around 2500? My block is different too, it is a LSX but same issue.

[pannetron]

My change didn't cure it but did reduce it enough to satisfy me.

[sgod1100]

Welp, bringing this back up yet again. Anyone have any new discoveries on these issues? I'm definitely STILL stumped on what to do!!